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спасибо, попробую применить, у мня в даче много JDY в разных местах торчат и снимать их оттуда для апдейта обычно лень.  А тут всё почти просто.  Блаадарю, налью при случае. 

 а 19200 не интересней будет?

дополню. Ногу изначально настраивать на вход, а когда нада сделать ресет, ногу делаем выходом и потом в LOW, иначе будет всегда ресет ещё на  setup е

а вообще sadman предлагал через собаку ресетится, может приведёт пример. 

На 19200 не синхронизируются загрузчик и дуда. Видимо костыль нарушает тайминги.
Тут нужно глубоко ковыряться в исходниках, я так далеко в этом не шарю.
Насчет ноги:
Ноги после сброса и так на входе.
В сетапе
Пишем сначала digitalWrite(PIN_RESET, HIGH);
Потом pinMode(PIN_RESET, OUTPUT);
На ноге будет сразу высокий уровень, ногу можно подключить к выводу DTR, соединенному
с RST через кондер.
Собакой ресетится нельзя, чтобы заработал загрузчик нужен только внешний ресет.

тоже самое будет работать и как я написал. 

я тоже так думаю, вот и интересно как это садман хотел сделать. Регистр MCUSR перед собакой прописать по нужному? 

Видимо нужно все же бутлоадер править, чтоб не обращал внимание на причину ресета. Тут обсуждалось

Еще пара ссылок на тему "Wireless reprogramming of Arduino" или "Over-the-Air uploading":

Для специфических задач и тех, у кого "цена не имеет значения":

Для  тех, кого еще не выбесили китайские nRF24L01:

Подпишусь

Попробовал не софт-железный сброс, а переход на адрес загрузчика - работает (по примеру).

#define BOOTLOADER_AREA     0x3800
void setup() {
   Serial.begin(9600);
  }   
void loop() {
  if (Serial.available()) {
    char inByte = Serial.read();// get incoming byte:
      if (inByte == CRC_EOP)
          Jump_to_bootloader();
  } 
  }
int  Jump_to_bootloader(void) {
          MCUSR = (_BV(EXTRF)); //;MCUSR = 0;
          cli();
          ((void (*)(void)) BOOTLOADER_AREA)();
          return 0;
  }  

разве строка 13 работает?  Имхо в MCUSR можно только сбрасывать биты. после 13 строки если вставить Serial.print (MCUSR), покажет 0 .  

ХЗ -). Кода MCUSR = 0; Загрузчик запускался, но либо входил в какой-то ступор либо бесконечный луп (лампочка моргала непереставая), на старт приложения (скетча)не выходил. Я глянул в шитодате MCUSR - R/W (чтение/запись) и рискнул подсунуть лодырю этот костыль MCUSR = (_BV(EXTRF)); пусть думает, что его запустили после внешнего сброса. Помогло.

чето у меня не помогло. Короче замучал я проминьку, она почему то на оптибуте перестала работать. Вроде ори оптибут уже заливаю и все одно. На родном лодыре робит, ХЗ вообще

Что конкретно не работает? Не заливает по UART? Оптибут самодельный или готовый? Нужны подробности. Фьюзы?

После заливки в очередной раз оптибута перестала прошиваться по уарт, возвращаю родной загрузчик - работает. Шью загрузчик  уной (arduino isp). Фьюзы в боардс от уны поставил, да и как уну пробовал  - нифига. Нашёл тут тему, у народа было точь в точь. Вроде как usb ttl виноват был. У меня пролифик, где то ещё фтди валялся. Попробую позже его. 

Hу не знаю, штук 15 оптибутов всяких заливал в последнее время, в том числе самодельных ( сам компилил). Ни каких проблем. Для экспериментов использую связку Promini - FT232R. Хочешь по SPI заливай, хочешь по UART.

О дак у меня такая же плата фтди. Ок попробую по spi тоже, только какой прогер выбирать в иде? 

Если кратко, то нужна специально пропатченная дуда, которой заменяют штатную. Если программировать из IDE то программатор нужно прописать в programmers.txt

короче дело было в программаторе arduino as ISP , скачал версию 1.8.8 и залил заново в уну скетч arduino ISP, теперь уна стала нормально в промини оптибут записывать . Продолжаем эксперименты.

Я пробую без радиоканала, просто через usb tll прошивку залить. с проводком DTR все нормально заливается. убираю провод, никак , нет ответа от МК после компиляции, но ресет пациента идет норм (по методу #11), видимо синхронизации IDE и бутлоадера нет . проводал и костыль из #2 ставить  и таймаут оптибута увеличивать. Мне кажется при компиляции оптибута у меня таймаут не увеличивается . Как это проверить? компилю такой строкой my atmega328 BAUD_RATE=57600 LED=B5 RS485=C3 TIMEOUT=8

Ваш оптибут из какой-то версии ардуины IDE. Там таймаут задан фиксированный 1с. Нужно править исходник. Я использую оптибут по ссылке #2.  

спустя пару дней мучений я все же смог это победить. Короче я застрял на том что пробовал все попытки на работе. Там толи ноут дерьмовый толи IDE корявая, но ее я вроде переставлял.  В общем ниче толком не работало. Даже на скорости 9600 оптибут не хотел работать, на 57600 работал. start led не мигал, хотя я настраивал его. меняя что-нибудь в optiboot.c и последующей компиляции лоадера изменения я не видел в работе. В общем целый день промучился.

Пришел домой, на домашнем компе все стало лучше. Все изменения в optiboot.c сразу стали работать, спустя 4 часа все таки прошилась минька без проводка DTR. 

Для прошивки по проводам (просто по уарт ттл) костыль _delay_ms(10) из пост #2 не потребовался. Также не потребовалось и увеличение таймаута бутлоадера (по умолчанию 1 секунда - работает. пробовал и на 9600 и на 57600). 

стандартный файл optiboot.c , скачанный с гитхаба по ссылке поста #2

#define FUNC_READ 1
#define FUNC_WRITE 1
/**********************************************************/
/* Optiboot bootloader for Arduino                        */
/*                                                        */
/* http://optiboot.googlecode.com                         */
/*                                                        */
/* Arduino-maintained version : See README.TXT            */
/* http://code.google.com/p/arduino/                      */
/*  It is the intent that changes not relevant to the     */
/*  Arduino production envionment get moved from the      */
/*  optiboot project to the arduino project in "lumps."   */
/*                                                        */
/* Heavily optimised bootloader that is faster and        */
/* smaller than the Arduino standard bootloader           */
/*                                                        */
/* Enhancements:                                          */
/*   Fits in 512 bytes, saving 1.5K of code space         */
/*   Higher baud rate speeds up programming               */
/*   Written almost entirely in C                         */
/*   Customisable timeout with accurate timeconstant      */
/*   Optional virtual UART. No hardware UART required.    */
/*   Optional virtual boot partition for devices without. */
/*                                                        */
/* What you lose:                                         */
/*   Implements a skeleton STK500 protocol which is       */
/*     missing several features including EEPROM          */
/*     programming and non-page-aligned writes            */
/*   High baud rate breaks compatibility with standard    */
/*     Arduino flash settings                             */
/*                                                        */
/* Fully supported:                                       */
/*   ATmega168 based devices  (Diecimila etc)             */
/*   ATmega328P based devices (Duemilanove etc)           */
/*                                                        */
/* Beta test (believed working.)                          */
/*   ATmega8 based devices (Arduino legacy)               */
/*   ATmega328 non-picopower devices                      */
/*   ATmega644P based devices (Sanguino)                  */
/*   ATmega1284P based devices                            */
/*   ATmega1280 based devices (Arduino Mega)              */
/*   ATmega2560 based devices (Arduino Mega)              */
/*                                                        */
/* Alpha test                                             */
/*   ATmega32                                             */
/*                                                        */
/* Work in progress:                                      */
/*   ATtiny84 based devices (Luminet)                     */
/*                                                        */
/* Does not support:                                      */
/*   USB based devices (eg. Teensy, Leonardo)             */
/*                                                        */
/* Assumptions:                                           */
/*   The code makes several assumptions that reduce the   */
/*   code size. They are all true after a hardware reset, */
/*   but may not be true if the bootloader is called by   */
/*   other means or on other hardware.                    */
/*     No interrupts can occur                            */
/*     UART and Timer 1 are set to their reset state      */
/*     SP points to RAMEND                                */
/*                                                        */
/* Code builds on code, libraries and optimisations from: */
/*   stk500boot.c          by Jason P. Kyle               */
/*   Arduino bootloader    http://arduino.cc              */
/*   Spiff's 1K bootloader http://spiffie.org/know/arduino_1k_bootloader/bootloader.shtml */
/*   avr-libc project      http://nongnu.org/avr-libc     */
/*   Adaboot               http://www.ladyada.net/library/arduino/bootloader.html */
/*   AVR305                Atmel Application Note         */
/*                                                        */

/* Copyright 2013-2015 by Bill Westfield.                 */
/* Copyright 2010 by Peter Knight.                        */
/*                                                        */
/* This program is free software; you can redistribute it */
/* and/or modify it under the terms of the GNU General    */
/* Public License as published by the Free Software       */
/* Foundation; either version 2 of the License, or        */
/* (at your option) any later version.                    */
/*                                                        */
/* This program is distributed in the hope that it will   */
/* be useful, but WITHOUT ANY WARRANTY; without even the  */
/* implied warranty of MERCHANTABILITY or FITNESS FOR A   */
/* PARTICULAR PURPOSE.  See the GNU General Public        */
/* License for more details.                              */
/*                                                        */
/* You should have received a copy of the GNU General     */
/* Public License along with this program; if not, write  */
/* to the Free Software Foundation, Inc.,                 */
/* 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA */
/*                                                        */
/* Licence can be viewed at                               */
/* http://www.fsf.org/licenses/gpl.txt                    */
/*                                                        */
/**********************************************************/


/**********************************************************/
/*                                                        */
/* Optional defines:                                      */
/*                                                        */
/**********************************************************/
/*                                                        */
/* BIGBOOT:                                              */
/* Build a 1k bootloader, not 512 bytes. This turns on    */
/* extra functionality.                                   */
/*                                                        */
/* BAUD_RATE:                                             */
/* Set bootloader baud rate.                              */
/*                                                        */
/* SOFT_UART:                                             */
/* Use AVR305 soft-UART instead of hardware UART.         */
/*                                                        */
/* LED_START_FLASHES:                                     */
/* Number of LED flashes on bootup.                       */
/*                                                        */
/* LED_DATA_FLASH:                                        */
/* Flash LED when transferring data. For boards without   */
/* TX or RX LEDs, or for people who like blinky lights.   */
/*                                                        */
/* SUPPORT_EEPROM:                                        */
/* Support reading and writing from EEPROM. This is not   */
/* used by Arduino, so off by default.                    */
/*                                                        */
/* WDTIME:                                                */
/* Bootloader timeout period, in seconds.                 */
/*  1 and 2 seconds are available on all chips            */
/*  4 and 8 are supported on most                         */
/*                                                        */
/* UART:                                                  */
/* UART number (0..n) for devices with more than          */
/* one hardware uart (644P, 1284P, etc)                   */
/*                                                        */
/**********************************************************/

/*
 * default values.
 */
#if !defined(BIGBOOT)
#  define BIGBOOT 0
#endif
#if !defined(SUPPORT_EEPROM)
#  define SUPPORT_EEPROM 0
#endif

#if !defined(SOFT_UART)
#  define SOFT_UART 0
#endif
#if !defined(UART)
#define UART 0
#endif
#if !defined(SINGLESPEED)
#define SINGLESPEED 0
#endif

#if !defined(APP_NOSPM)
#define APP_NOSPM 0
#endif

#if !defined(LED_START_FLASHES)
#define LED_START_FLASHES 0
#endif
#if !defined(LED_DATA_FLASH)
#  define LED_DATA_FLASH 0
#endif
#if !defined(LED_START_ON)
#  define LED_START_ON 0
#endif


/**********************************************************/
/* Version Numbers!                                       */
/*                                                        */
/* Arduino Optiboot now includes this Version number in   */
/* the source and object code.                            */
/*                                                        */
/* Version 3 was released as zip from the optiboot        */
/*  repository and was distributed with Arduino 0022.     */
/* Version 4 starts with the arduino repository commit    */
/*  that brought the arduino repository up-to-date with   */
/*  the optiboot source tree changes since v3.            */
/* Version 5 was created at the time of the new Makefile  */
/*  structure (Mar, 2013), even though no binaries changed*/
/* Version 6 added EEPROM support, including causing an   */
/*  error when trying to write eeprom with versions that  */
/*  didn't have the code there. Makefiles were further    */
/*  restructured.  Overlapping SPM/download removed.      */
/* Version 7 straightened out the MCUSR and RESET         */
/*  handling, did MORE Makefile mods.  EEPROM support now */
/*  fits in 512 bytes, if you turn off LED Blinking.      */
/*  Various bigboot and virboot targets were fixed.       */
/* Version 8.0 adds the do_spm code callable from Apps.   */
/*                                                        */
/* It would be good if versions implemented outside the   */
/*  official repository used an out-of-seqeunce version   */
/*  number (like 104.6 if based on based on 4.5) to       */
/*  prevent collisions.  The CUSTOM_VERSION=n option      */
/*  adds n to the high version to facilitate this.        */
/*                                                        */
/**********************************************************/

/**********************************************************/
/* Edit History:            */
/*                */
/* Aug 2019             */
/* 8.1  WestfW Fix bug in calculation of Vboot offset     */
/* Sep 2018             */
/* 8.0  WestfW (and Majekw and MCUDude)       */
/*      Include do_spm routine callable from the app      */
/*      at BOOTSTART+2, controllable with compile option  */
/* July 2018              */
/* 7.0  WestfW (with much input from Others)      */
/*  Fix MCUSR treatement as per much discussion,    */
/*   Patches by MarkG55, majekw.  Preserve value    */
/*   for the application, as much as possible.    */
/*   see https://github.com/Optiboot/optiboot/issues/97 */
/*  Optimize a bit by implementing a union for the    */
/*   various 16bit address values used (based on    */
/*   observation by "aweatherguy", but different.)    */
/*  Slightly optimize math in VIRTUAL_BOOT code   */
/*  Add some virboot targets, fix some fuses.   */
/*  Implement LED_START_ON; less code than flashes    */
/* Aug 2014             */
/* 6.2 WestfW: make size of length variables dependent    */
/*              on the SPM_PAGESIZE.  This saves space    */
/*              on the chips where it's most important.   */
/* 6.1 WestfW: Fix OPTIBOOT_CUSTOMVER (send it!)    */
/*             Make no-wait mod less picky about    */
/*               skipping the bootloader.     */
/*             Remove some dead code        */
/* Jun 2014             */
/* 6.0 WestfW: Modularize memory read/write functions   */
/*             Remove serial/flash overlap      */
/*              (and all references to NRWWSTART/etc)   */
/*             Correctly handle pagesize > 255bytes       */
/*             Add EEPROM support in BIGBOOT (1284)       */
/*             EEPROM write on small chips now causes err */
/*             Split Makefile into smaller pieces         */
/*             Add Wicked devices Wildfire      */
/*         Move UART=n conditionals into pin_defs.h   */
/*         Remove LUDICOUS_SPEED option     */
/*         Replace inline assembler for .version      */
/*              and add OPTIBOOT_CUSTOMVER for user code  */
/*             Fix LED value for Bobuino (Makefile)       */
/*             Make all functions explicitly inline or    */
/*              noinline, so we fit when using gcc4.8     */
/*             Change optimization options for gcc4.8   */
/*             Make ENV=arduino work in 1.5.x trees.    */
/* May 2014                                               */
/* 5.0 WestfW: Add support for 1Mbps UART                 */
/* Mar 2013                                               */
/* 5.0 WestfW: Major Makefile restructuring.              */
/*             See Makefile and pin_defs.h                */
/*             (no binary changes)                        */
/*                                                        */
/* 4.6 WestfW/Pito: Add ATmega32 support                  */
/* 4.6 WestfW/radoni: Don't set LED_PIN as an output if   */
/*                    not used. (LED_START_FLASHES = 0)   */
/* Jan 2013             */
/* 4.6 WestfW/dkinzer: use autoincrement lpm for read     */
/* 4.6 WestfW/dkinzer: pass reset cause to app in R2      */
/* Mar 2012                                               */
/* 4.5 WestfW: add infrastructure for non-zero UARTS.     */
/* 4.5 WestfW: fix SIGNATURE_2 for m644 (bad in avr-libc) */
/* Jan 2012:                                              */
/* 4.5 WestfW: fix NRWW value for m1284.                  */
/* 4.4 WestfW: use attribute OS_main instead of naked for */
/*             main().  This allows optimizations that we */
/*             count on, which are prohibited in naked    */
/*             functions due to PR42240.  (keeps us less  */
/*             than 512 bytes when compiler is gcc4.5     */
/*             (code from 4.3.2 remains the same.)        */
/* 4.4 WestfW and Maniacbug:  Add m1284 support.  This    */
/*             does not change the 328 binary, so the     */
/*             version number didn't change either. (?)   */
/* June 2011:                                             */
/* 4.4 WestfW: remove automatic soft_uart detect (didn't  */
/*             know what it was doing or why.)  Added a   */
/*             check of the calculated BRG value instead. */
/*             Version stays 4.4; existing binaries are   */
/*             not changed.                               */
/* 4.4 WestfW: add initialization of address to keep      */
/*             the compiler happy.  Change SC'ed targets. */
/*             Return the SW version via READ PARAM       */
/* 4.3 WestfW: catch framing errors in getch(), so that   */
/*             AVRISP works without HW kludges.           */
/*  http://code.google.com/p/arduino/issues/detail?id=368n*/
/* 4.2 WestfW: reduce code size, fix timeouts, change     */
/*             verifySpace to use WDT instead of appstart */
/* 4.1 WestfW: put version number in binary.      */
/**********************************************************/

#define OPTIBOOT_MAJVER 8
#define OPTIBOOT_MINVER 1

/*
 * OPTIBOOT_CUSTOMVER should be defined (by the makefile) for custom edits
 * of optiboot.  That way you don't wind up with very different code that
 * matches the version number of a "released" optiboot.
 */

#if !defined(OPTIBOOT_CUSTOMVER)
#define OPTIBOOT_CUSTOMVER 0
#endif

unsigned const int __attribute__((section(".version"))) 
optiboot_version = 256*(OPTIBOOT_MAJVER + OPTIBOOT_CUSTOMVER) + OPTIBOOT_MINVER;


#include <inttypes.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <avr/eeprom.h>

/*
 * optiboot uses several "address" variables that are sometimes byte pointers,
 * sometimes word pointers. sometimes 16bit quantities, and sometimes built
 * up from 8bit input characters.  avr-gcc is not great at optimizing the
 * assembly of larger words from bytes, but we can use the usual union to
 * do this manually.  Expanding it a little, we can also get rid of casts.
 */
typedef union {
  uint8_t  *bptr;
  uint16_t *wptr;
  uint16_t word;
  uint8_t bytes[2];
} addr16_t;

/*
 * Note that we use a replacement of "boot.h"
 * <avr/boot.h> uses sts instructions, but this version uses out instructions
 * This saves cycles and program memory, if possible.
 * boot_opt.h pulls in the standard boot.h for the odd target (?)
 */
#include "boot_opt.h"


// We don't use <avr/wdt.h> as those routines have interrupt overhead we don't need.

/*
 * pin_defs.h
 * This contains most of the rather ugly defines that implement our
 * ability to use UART=n and LED=D3, and some avr family bit name differences.
 */
#include "pin_defs.h"

/*
 * stk500.h contains the constant definitions for the stk500v1 comm protocol
 */
#include "stk500.h"

/* set the UART baud rate defaults */
#ifndef BAUD_RATE
#if F_CPU >= 8000000L
#define BAUD_RATE   115200L // Highest rate Avrdude win32 will support
#elif F_CPU >= 1000000L
#define BAUD_RATE   9600L   // 19200 also supported, but with significant error
#elif F_CPU >= 128000L
#define BAUD_RATE   4800L   // Good for 128kHz internal RC
#else
#define BAUD_RATE 1200L     // Good even at 32768Hz
#endif
#endif

#if (SOFT_UART == 0)
#if SINGLESPEED
/* Single speed option */
#define BAUD_SETTING (( (F_CPU + BAUD_RATE * 8L) / ((BAUD_RATE * 16L))) - 1 )
#define BAUD_ACTUAL (F_CPU/(16 * ((BAUD_SETTING)+1)))
#else
/* Normal U2X usage */
#define BAUD_SETTING (( (F_CPU + BAUD_RATE * 4L) / ((BAUD_RATE * 8L))) - 1 )
#define BAUD_ACTUAL (F_CPU/(8 * ((BAUD_SETTING)+1)))
#endif
#if BAUD_ACTUAL <= BAUD_RATE
  #define BAUD_ERROR (( 100*(BAUD_RATE - BAUD_ACTUAL) ) / BAUD_RATE)
  #if BAUD_ERROR >= 5
    #error BAUD_RATE off by greater than -5%
  #elif BAUD_ERROR >= 2  && !defined(PRODUCTION)
    #warning BAUD_RATE off by greater than -2%
  #endif
#else
  #define BAUD_ERROR (( 100*(BAUD_ACTUAL - BAUD_RATE) ) / BAUD_RATE)
  #if BAUD_ERROR >= 5
    #error BAUD_RATE off by greater than 5%
  #elif BAUD_ERROR >= 2  && !defined(PRODUCTION)
    #warning BAUD_RATE off by greater than 2%
  #endif
#endif

#if BAUD_SETTING > 250
#error Unachievable baud rate (too slow) BAUD_RATE 
#endif // baud rate slow check
#if (BAUD_SETTING - 1) < 3
#if BAUD_ERROR != 0 // permit high bitrates (ie 1Mbps@16MHz) if error is zero
#error Unachievable baud rate (too fast) BAUD_RATE 
#endif
#endif // baud rate fast check
#endif // SOFT_UART

/* Watchdog settings */
#define WATCHDOG_OFF    (0)
#define WATCHDOG_16MS   (_BV(WDE))
#define WATCHDOG_32MS   (_BV(WDP0) | _BV(WDE))
#define WATCHDOG_64MS   (_BV(WDP1) | _BV(WDE))
#define WATCHDOG_125MS  (_BV(WDP1) | _BV(WDP0) | _BV(WDE))
#define WATCHDOG_250MS  (_BV(WDP2) | _BV(WDE))
#define WATCHDOG_500MS  (_BV(WDP2) | _BV(WDP0) | _BV(WDE))
#define WATCHDOG_1S     (_BV(WDP2) | _BV(WDP1) | _BV(WDE))
#define WATCHDOG_2S     (_BV(WDP2) | _BV(WDP1) | _BV(WDP0) | _BV(WDE))
#ifdef  WDP3
#define WATCHDOG_4S     (_BV(WDP3) | _BV(WDE))
#define WATCHDOG_8S     (_BV(WDP3) | _BV(WDP0) | _BV(WDE))
#endif

/*
 * Watchdog timeout translations from human readable to config vals
 */
#ifndef WDTTIME
# define WDTPERIOD WATCHDOG_1S  // 1 second default
#elif WDTTIME == 1
# define WDTPERIOD WATCHDOG_1S  // 1 second
#elif WDTTIME == 2
# define WDTPERIOD WATCHDOG_2S  // 2 seconds
#elif defined(WDP3) && (WDTTIME == 4)
# define WDTPERIOD WATCHDOG_4S  // 4 seconds
#elif defined(WDP3) && (WDTTIME == 8)
# define WDTPERIOD WATCHDOG_8S  // 8 seconds
#else
#error Invalid TIMEOUT
#endif

/*
 * We can never load flash with more than 1 page at a time, so we can save
 * some code space on parts with smaller pagesize by using a smaller int.
 */
#if SPM_PAGESIZE > 255
typedef uint16_t pagelen_t ;
#define GETLENGTH(len) len = getch()<<8; len |= getch()
#else
typedef uint8_t pagelen_t;
#define GETLENGTH(len) (void) getch() /* skip high byte */; len = getch()
#endif


/* Function Prototypes
 * The main() function is in init9, which removes the interrupt vector table
 * we don't need. It is also 'OS_main', which means the compiler does not
 * generate any entry or exit code itself (but unlike 'naked', it doesn't
 * supress some compile-time options we want.)
 */

void pre_main(void) __attribute__ ((naked)) __attribute__ ((section (".init8")));
int main(void) __attribute__ ((OS_main)) __attribute__ ((section (".init9"))) __attribute__((used));

void __attribute__((noinline)) __attribute__((leaf)) putch(char);
uint8_t __attribute__((noinline)) __attribute__((leaf)) getch(void) ;
void __attribute__((noinline)) verifySpace();
void __attribute__((noinline)) watchdogConfig(uint8_t x);

static void getNch(uint8_t);
#if LED_START_FLASHES > 0
static inline void flash_led(uint8_t);
#endif
static inline void watchdogReset();
static inline void writebuffer(int8_t memtype, addr16_t mybuff,
             addr16_t address, pagelen_t len);
static inline void read_mem(uint8_t memtype,
          addr16_t, pagelen_t len);

#ifdef SOFT_UART
void uartDelay() __attribute__ ((naked));
#endif

/*
 * RAMSTART should be self-explanatory.  It's bigger on parts with a
 * lot of peripheral registers.  Let 0x100 be the default
 * Note that RAMSTART (for optiboot) need not be exactly at the start of RAM.
 */
#if !defined(RAMSTART)  // newer versions of gcc avr-libc define RAMSTART
#define RAMSTART 0x100
#if defined (__AVR_ATmega644P__)
// correct for a bug in avr-libc
#undef SIGNATURE_2
#define SIGNATURE_2 0x0A
#elif defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
#undef RAMSTART
#define RAMSTART (0x200)
#endif
#endif

/* C zero initialises all global variables. However, that requires */
/* These definitions are NOT zero initialised, but that doesn't matter */
/* This allows us to drop the zero init code, saving us memory */
static addr16_t buff = {(uint8_t *)(RAMSTART)};

/* Virtual boot partition support */
#ifdef VIRTUAL_BOOT_PARTITION

// RAM locations to save vector info (temporarilly)
#define rstVect0_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+4))
#define rstVect1_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+5))
#define saveVect0_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+6))
#define saveVect1_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+7))

#define RSTVEC_ADDRESS 0  // flash address where vectors start.
// Vector to save original reset jump:
//   SPM Ready is least probably used, so it's default
//   if not, use old way WDT_vect_num,
//   or simply set custom save_vect_num in Makefile using vector name
//   or even raw number.
#if !defined (save_vect_num)
#if defined (SPM_RDY_vect_num)
#define save_vect_num (SPM_RDY_vect_num)
#elif defined (SPM_READY_vect_num)
#define save_vect_num (SPM_READY_vect_num)
#elif defined (EE_RDY_vect_num)
#define save_vect_num (EE_RDY_vect_num)
#elif defined (EE_READY_vect_num)
#define save_vect_num (EE_READY_vect_num)
#elif defined (WDT_vect_num)
#define save_vect_num (WDT_vect_num)
#else
#error Cant find SPM or WDT interrupt vector for this CPU
#endif
#endif //save_vect_num

// check if it's on the same page (code assumes that)

#if FLASHEND > 8192
// AVRs with more than 8k of flash have 4-byte vectors, and use jmp.
//  We save only 16 bits of address, so devices with more than 128KB
//  may behave wrong for upper part of address space.
#define rstVect0 2
#define rstVect1 3
#define saveVect0 (save_vect_num*4+2)
#define saveVect1 (save_vect_num*4+3)
#define appstart_vec (save_vect_num*2)

// address of page that will have the saved vector
#define SAVVEC_ADDRESS (SPM_PAGESIZE*(save_vect_num/(SPM_PAGESIZE/4)))

#else

// AVRs with up to 8k of flash have 2-byte vectors, and use rjmp.
#define rstVect0 0
#define rstVect1 1
#define saveVect0 (save_vect_num*2)
#define saveVect1 (save_vect_num*2+1)
#define appstart_vec (save_vect_num)

// address of page that will have the saved vector
#define SAVVEC_ADDRESS (SPM_PAGESIZE*(save_vect_num/(SPM_PAGESIZE/2)))
#endif

#else

#define appstart_vec (0)

#endif // VIRTUAL_BOOT_PARTITION


/* everything that needs to run VERY early */
void pre_main(void) {
  // Allow convenient way of calling do_spm function - jump table,
  //   so entry to this function will always be here, indepedent of compilation,
  //   features etc
  asm volatile (
    " rjmp  1f\n"
#if APP_NOSPM
    "   ret\n"   // if do_spm isn't include, return without doing anything
#else
    " rjmp  do_spm\n"
#endif
    "1:\n"
  );
}


/* main program starts here */
int main(void) {
  uint8_t ch;

  /*
   * Making these local and in registers prevents the need for initializing
   * them, and also saves space because code no longer stores to memory.
   * (initializing address keeps the compiler happy, but isn't really
   *  necessary, and uses 4 bytes of flash.)
   */
  register addr16_t address;
  register pagelen_t  length;

  // After the zero init loop, this is the first code to run.
  //
  // This code makes the following assumptions:
  //  No interrupts will execute
  //  SP points to RAMEND
  //  r1 contains zero
  //
  // If not, uncomment the following instructions:
  // cli();
  asm volatile ("clr __zero_reg__");

#if defined(__AVR_ATmega8__) || defined(__AVR_ATmega8515__) ||    \
    defined(__AVR_ATmega8535__) || defined (__AVR_ATmega16__) ||  \
    defined (__AVR_ATmega32__) || defined (__AVR_ATmega64__)  ||  \
    defined (__AVR_ATmega128__) || defined (__AVR_ATmega162__)
  SP=RAMEND;  // This is done by hardware reset
#endif

#if defined(OSCCAL_VALUE)
  OSCCAL = OSCCAL_VALUE;
#endif

  /*
   * Protect as much from MCUSR as possible for application
   * and still skip bootloader if not necessary
   * 
   * Code by MarkG55
   * see discusion in https://github.com/Optiboot/optiboot/issues/97
   */
#if defined(__AVR_ATmega8515__) || defined(__AVR_ATmega8535__) || \
    defined(__AVR_ATmega16__)   || defined(__AVR_ATmega162__) ||  \
    defined (__AVR_ATmega128__)
  ch = MCUCSR;
#else
  ch = MCUSR;
#endif
  // Skip all logic and run bootloader if MCUSR is cleared (application request)
  if (ch != 0) {
      /*
       * To run the boot loader, External Reset Flag must be set.
       * If not, we could make shortcut and jump directly to application code.
       * Also WDRF set with EXTRF is a result of Optiboot timeout, so we
       * shouldn't run bootloader in loop :-) That's why:
       *  1. application is running if WDRF is cleared
       *  2. we clear WDRF if it's set with EXTRF to avoid loops
       * One problematic scenario: broken application code sets watchdog timer 
       * without clearing MCUSR before and triggers it quickly. But it's
       * recoverable by power-on with pushed reset button.
       */
      if ((ch & (_BV(WDRF) | _BV(EXTRF))) != _BV(EXTRF)) { 
    if (ch & _BV(EXTRF)) {
        /*
         * Clear WDRF because it was most probably set by wdr in bootloader.
         * It's also needed to avoid loop by broken application which could
         * prevent entering bootloader.
         * '&' operation is skipped to spare few bytes as bits in MCUSR
         * can only be cleared.
         */
#if defined(__AVR_ATmega8515__) || defined(__AVR_ATmega8535__) || \
    defined(__AVR_ATmega16__)   || defined(__AVR_ATmega162__) ||  \
    defined(__AVR_ATmega128__)
               // Fix missing definitions in avr-libc
        MCUCSR = ~(_BV(WDRF));
#else
        MCUSR = ~(_BV(WDRF));
#endif
    }
    /* 
     * save the reset flags in the designated register
     * This can be saved in a main program by putting code in .init0 (which
     * executes before normal c init code) to save R2 to a global variable.
     */
    __asm__ __volatile__ ("mov r2, %0\n" :: "r" (ch));

    // switch off watchdog
    watchdogConfig(WATCHDOG_OFF);
    // Note that appstart_vec is defined so that this works with either
    // real or virtual boot partitions.
     __asm__ __volatile__ (
      // Jump to 'save' or RST vector
#ifdef VIRTUAL_BOOT_PARTITION
      // full code version for virtual boot partition
      "ldi r30,%[rstvec]\n"
      "clr r31\n"
      "ijmp\n"::[rstvec] "M"(appstart_vec)
#else
#ifdef RAMPZ
      // use absolute jump for devices with lot of flash
      "jmp 0\n"::
#else
      // use rjmp to go around end of flash to address 0
      // it uses fact that optiboot_version constant is 2 bytes before end of flash
      "rjmp optiboot_version+2\n"
#endif //RAMPZ
#endif //VIRTUAL_BOOT_PARTITION
    );
      }
  }

#if LED_START_FLASHES > 0
  // Set up Timer 1 for timeout counter
#if defined(__AVR_ATtiny261__)||defined(__AVR_ATtiny461__)||defined(__AVR_ATtiny861__)
  TCCR1B = 0x0E; //div 8196 - we could divide by less since it's a 10-bit counter, but why? 
#elif defined(__AVR_ATtiny25__)||defined(__AVR_ATtiny45__)||defined(__AVR_ATtiny85__)
  TCCR1 = 0x0E; //div 8196 - it's an 8-bit timer. 
#elif defined(__AVR_ATtiny43__)
  #error "LED flash for Tiny43 not yet supported"
#else
  TCCR1B = _BV(CS12) | _BV(CS10); // div 1024
#endif
#endif


#if (SOFT_UART == 0)
  #if defined(__AVR_ATmega8__) || defined (__AVR_ATmega8515__) || \
      defined (__AVR_ATmega8535__) || defined (__AVR_ATmega16__) || \
      defined (__AVR_ATmega32__)
#if (SINGLESPEED == 0)
  UCSRA = _BV(U2X); //Double speed mode USART
  #endif //singlespeed
  UCSRB = _BV(RXEN) | _BV(TXEN);  // enable Rx & Tx
  UCSRC = _BV(URSEL) | _BV(UCSZ1) | _BV(UCSZ0);  // config USART; 8N1
  UBRRL = (uint8_t)BAUD_SETTING;
  #else // mega8/etc
    #ifdef LIN_UART
  //DDRB|=3;
  LINCR = (1 << LSWRES); 
  //LINBRRL = (((F_CPU * 10L / 32L / BAUD_RATE) + 5L) / 10L) - 1; 
  LINBRRL=(uint8_t)BAUD_SETTING;
  LINBTR = (1 << LDISR) | (8 << LBT0); 
  LINCR = _BV(LENA) | _BV(LCMD2) | _BV(LCMD1) | _BV(LCMD0); 
  LINDAT=0;
    #else
      #if (SINGLESPEED == 0)
  UART_SRA = _BV(U2X0); //Double speed mode USART0
      #endif
  UART_SRB = _BV(RXEN0) | _BV(TXEN0);
  UART_SRC = _BV(UCSZ00) | _BV(UCSZ01);
  UART_SRL = (uint8_t)BAUD_SETTING;
    #endif // LIN_UART
  #endif // mega8/etc
#endif // soft_uart

  // Set up watchdog to trigger after desired timeout
  watchdogConfig(WDTPERIOD);

#if (LED_START_FLASHES > 0) || LED_DATA_FLASH || LED_START_ON
  /* Set LED pin as output */
  LED_DDR |= _BV(LED);
#endif

#if SOFT_UART
  /* Set TX pin as output */
  UART_DDR |= _BV(UART_TX_BIT);
#endif

#if LED_START_FLASHES > 0
  /* Flash onboard LED to signal entering of bootloader */
  flash_led(LED_START_FLASHES * 2);
#else
#if LED_START_ON
  /* Turn on LED to indicate starting bootloader (less code!) */
  LED_PORT |= _BV(LED);
#endif
#endif

  /* Forever loop: exits by causing WDT reset */
  for (;;) {
    /* get character from UART */
    ch = getch();

    if(ch == STK_GET_PARAMETER) {
      unsigned char which = getch();
      verifySpace();
      /*
       * Send optiboot version as "SW version"
       * Note that the references to memory are optimized away.
       */
      if (which == STK_SW_MINOR) {
    putch(optiboot_version & 0xFF);
      } else if (which == STK_SW_MAJOR) {
    putch(optiboot_version >> 8);
      } else {
  /*
   * GET PARAMETER returns a generic 0x03 reply for
         * other parameters - enough to keep Avrdude happy
   */
  putch(0x03);
      }
    }
    else if(ch == STK_SET_DEVICE) {
      // SET DEVICE is ignored
      getNch(20);
    }
    else if(ch == STK_SET_DEVICE_EXT) {
      // SET DEVICE EXT is ignored
      getNch(5);
    }
    else if(ch == STK_LOAD_ADDRESS) {
      // LOAD ADDRESS
      address.bytes[0] = getch();
      address.bytes[1] = getch();
#ifdef RAMPZ
      // Transfer top bit to LSB in RAMPZ
      if (address.bytes[1] & 0x80) {
        RAMPZ |= 0x01;
      }
      else {
        RAMPZ &= 0xFE;
      }
#endif
      address.word *= 2; // Convert from word address to byte address
      verifySpace();
    }
    else if(ch == STK_UNIVERSAL) {
#ifdef RAMPZ
      // LOAD_EXTENDED_ADDRESS is needed in STK_UNIVERSAL for addressing more than 128kB
      if ( AVR_OP_LOAD_EXT_ADDR == getch() ) {
        // get address
        getch();  // get '0'
        RAMPZ = (RAMPZ & 0x01) | ((getch() << 1) & 0xff);  // get address and put it in RAMPZ
        getNch(1); // get last '0'
        // response
        putch(0x00);
      }
      else {
        // everything else is ignored
        getNch(3);
        putch(0x00);
      }
#else
      // UNIVERSAL command is ignored
      getNch(4);
      putch(0x00);
#endif
    }
    /* Write memory, length is big endian and is in bytes */
    else if(ch == STK_PROG_PAGE) {
      // PROGRAM PAGE - we support flash programming only, not EEPROM
      uint8_t desttype;
      uint8_t *bufPtr;
      pagelen_t savelength;

      GETLENGTH(length);
      savelength = length;
      desttype = getch();

      // read a page worth of contents
      bufPtr = buff.bptr;
      do *bufPtr++ = getch();
      while (--length);

      // Read command terminator, start reply
      verifySpace();

#ifdef VIRTUAL_BOOT_PARTITION
/*
 *              How the Virtual Boot Partition works:
 * At the beginning of a normal AVR program are a set of vectors that
 * implement the interrupt mechanism.  Each vector is usually a single
 * instruction that dispatches to the appropriate ISR.
 * The instruction is normally an rjmp (on AVRs with 8k or less of flash)
 * or jmp instruction, and the 0th vector is executed on reset and jumps
 * to the start of the user program:
 * vectors: jmp startup
 *          jmp ISR1
 *          jmp ISR2
 *             :      ;; etc
 *          jmp lastvector
 * To implement the "Virtual Boot Partition", Optiboot detects when the
 * flash page containing the vectors is being programmed, and replaces the
 * startup vector with a jump to te beginning of Optiboot.  Then it saves
 * the applications's startup vector in another (must be unused by the
 * application), and finally programs the page with the changed vectors.
 * Thereafter, on reset, the vector will dispatch to the beginning of
 * Optiboot.  When Optiboot decides that it will run the user application,
 * it fetches the saved start address from the unused vector, and jumps
 * there.
 * The logic is dependent on size of flash, and whether the reset vector is
 * on the same flash page as the saved start address.
 */

#if FLASHEND > 8192
/*
 * AVR with 4-byte ISR Vectors and "jmp"
 * WARNING: this works only up to 128KB flash!
 */
#if FLASHEND > (128*1024)
#error "Can't use VIRTUAL_BOOT_PARTITION with more than 128k of Flash"
#endif
      if (address.word == RSTVEC_ADDRESS) {
  // This is the reset vector page. We need to live-patch the
  // code so the bootloader runs first.
  //
  // Save jmp targets (for "Verify")
  rstVect0_sav = buff.bptr[rstVect0];
  rstVect1_sav = buff.bptr[rstVect1];

        // Add "jump to Optiboot" at RESET vector
        // WARNING: this works as long as 'main' is in first section
        buff.bptr[rstVect0] = ((uint16_t)pre_main) & 0xFF;
        buff.bptr[rstVect1] = ((uint16_t)pre_main) >> 8;

#if (SAVVEC_ADDRESS != RSTVEC_ADDRESS)
// the save_vector is not necessarilly on the same flash page as the reset
//  vector.  If it isn't, we've waiting to actually write it.
      } else if (address.word == SAVVEC_ADDRESS) {
    // Save old values for Verify
    saveVect0_sav = buff.bptr[saveVect0 - SAVVEC_ADDRESS];
    saveVect1_sav = buff.bptr[saveVect1 - SAVVEC_ADDRESS];

    // Move RESET jmp target to 'save' vector
    buff.bptr[saveVect0 - SAVVEC_ADDRESS] = rstVect0_sav;
    buff.bptr[saveVect1 - SAVVEC_ADDRESS] = rstVect1_sav;
      }
#else 
        // Save old values for Verify
        saveVect0_sav = buff.bptr[saveVect0];
  saveVect1_sav = buff.bptr[saveVect1];

        // Move RESET jmp target to 'save' vector
        buff.bptr[saveVect0] = rstVect0_sav;
        buff.bptr[saveVect1] = rstVect1_sav;
    }
#endif

#else
/*
 * AVR with 2-byte ISR Vectors and rjmp
 */
      if (address.word == rstVect0) {
        // This is the reset vector page. We need to live-patch
        // the code so the bootloader runs first.
        //
        // Move RESET vector to 'save' vector
  // Save jmp targets (for "Verify")
  rstVect0_sav = buff.bptr[rstVect0];
  rstVect1_sav = buff.bptr[rstVect1];
  addr16_t vect;
  vect.word = ((uint16_t)pre_main-1);
  // Instruction is a relative jump (rjmp), so recalculate.
  // an RJMP instruction is 0b1100xxxx xxxxxxxx, so we should be able to
  // do math on the offsets without masking it off first.
  // Note that rjmp is relative to the already incremented PC, so the
  //  offset is one less than you might expect.
  buff.bptr[0] = vect.bytes[0]; // rjmp to start of bootloader
  buff.bptr[1] = vect.bytes[1] | 0xC0;  // make an "rjmp"
#if (SAVVEC_ADDRESS != RSTVEC_ADDRESS)
      } else if (address.word == SAVVEC_ADDRESS) {
  addr16_t vect;
  vect.bytes[0] = rstVect0_sav;
  vect.bytes[1] = rstVect1_sav;
  // Save old values for Verify
  saveVect0_sav = buff.bptr[saveVect0 - SAVVEC_ADDRESS];
  saveVect1_sav = buff.bptr[saveVect1 - SAVVEC_ADDRESS];

  vect.word = (vect.word-save_vect_num); //substract 'save' interrupt position
        // Move RESET jmp target to 'save' vector
        buff.bptr[saveVect0 - SAVVEC_ADDRESS] = vect.bytes[0];
        buff.bptr[saveVect1 - SAVVEC_ADDRESS] = (vect.bytes[1] & 0x0F)| 0xC0;  // make an "rjmp"
      }
#else

      // Save old values for Verify
      saveVect0_sav = buff.bptr[saveVect0];
      saveVect1_sav = buff.bptr[saveVect1];

      vect.bytes[0] = rstVect0_sav;
      vect.bytes[1] = rstVect1_sav;
      vect.word = (vect.word-save_vect_num); //substract 'save' interrupt position
      // Move RESET jmp target to 'save' vector
      buff.bptr[saveVect0] = vect.bytes[0];
      buff.bptr[saveVect1] = (vect.bytes[1] & 0x0F)| 0xC0;  // make an "rjmp"
      // Add rjmp to bootloader at RESET vector
      vect.word = ((uint16_t)pre_main-1); // (main) is always <= 0x0FFF; no masking needed.
      buff.bptr[0] = vect.bytes[0]; // rjmp 0x1c00 instruction
  }
  
#endif

#endif // FLASHEND
#endif // VBP

      writebuffer(desttype, buff, address, savelength);


    }
    /* Read memory block mode, length is big endian.  */
    else if(ch == STK_READ_PAGE) {
      uint8_t desttype;
      GETLENGTH(length);

      desttype = getch();

      verifySpace();

      read_mem(desttype, address, length);
    }

    /* Get device signature bytes  */
    else if(ch == STK_READ_SIGN) {
      // READ SIGN - return what Avrdude wants to hear
      verifySpace();
      putch(SIGNATURE_0);
      putch(SIGNATURE_1);
      putch(SIGNATURE_2);
    }
    else if (ch == STK_LEAVE_PROGMODE) { /* 'Q' */
      // Adaboot no-wait mod
      watchdogConfig(WATCHDOG_16MS);
      verifySpace();
    }
    else {
      // This covers the response to commands like STK_ENTER_PROGMODE
      verifySpace();
    }
    putch(STK_OK);
  }
}

void putch(char ch) {
#if (SOFT_UART == 0)
  #ifndef LIN_UART
    while (!(UART_SRA & _BV(UDRE0))) {  /* Spin */ }
  #else
    while (!(LINSIR & _BV(LTXOK)))   {  /* Spin */ }
  #endif

  UART_UDR = ch;

#else
  __asm__ __volatile__ (
    "   com %[ch]\n" // ones complement, carry set
    "   sec\n"
    "1: brcc 2f\n"
    "   cbi %[uartPort],%[uartBit]\n"
    "   rjmp 3f\n"
    "2: sbi %[uartPort],%[uartBit]\n"
    "   nop\n"
    "3: rcall uartDelay\n"
    "   rcall uartDelay\n"
    "   lsr %[ch]\n"
    "   dec %[bitcnt]\n"
    "   brne 1b\n"
    :
    :
      [bitcnt] "d" (10),
      [ch] "r" (ch),
      [uartPort] "I" (_SFR_IO_ADDR(UART_PORT)),
      [uartBit] "I" (UART_TX_BIT)
    :
      "r25"
  );
#endif
}

uint8_t getch(void) {
  uint8_t ch;

#if LED_DATA_FLASH
#if defined(__AVR_ATmega8__)    || defined(__AVR_ATmega8515__) || \
    defined(__AVR_ATmega8535__) || defined(__AVR_ATmega16__)   || \
    defined(__AVR_ATmega162__)  || defined(__AVR_ATmega32__)   || \
    defined(__AVR_ATmega64__)   || defined(__AVR_ATmega128__)
  LED_PORT ^= _BV(LED);
#else
  LED_PIN |= _BV(LED);
#endif
#endif

#if SOFT_UART
    watchdogReset();
  __asm__ __volatile__ (
    "1: sbic  %[uartPin],%[uartBit]\n"  // Wait for start edge
    "   rjmp  1b\n"
    "   rcall uartDelay\n"          // Get to middle of start bit
    "2: rcall uartDelay\n"              // Wait 1 bit period
    "   rcall uartDelay\n"              // Wait 1 bit period
    "   clc\n"
    "   sbic  %[uartPin],%[uartBit]\n"
    "   sec\n"
    "   dec   %[bitCnt]\n"
    "   breq  3f\n"
    "   ror   %[ch]\n"
    "   rjmp  2b\n"
    "3:\n"
    :
      [ch] "=r" (ch)
    :
      [bitCnt] "d" (9),
      [uartPin] "I" (_SFR_IO_ADDR(UART_PIN)),
      [uartBit] "I" (UART_RX_BIT)
    :
      "r25"
);
#else
#ifndef LIN_UART
  while(!(UART_SRA & _BV(RXC0)))  {  /* Spin */ }
  if (!(UART_SRA & _BV(FE0))) {
#else
  while(!(LINSIR & _BV(LRXOK)))  {  /* Spin */ }
  if (!(LINSIR & _BV(LFERR))) {
#endif
      /*
       * A Framing Error indicates (probably) that something is talking
       * to us at the wrong bit rate.  Assume that this is because it
       * expects to be talking to the application, and DON'T reset the
       * watchdog.  This should cause the bootloader to abort and run
       * the application "soon", if it keeps happening.  (Note that we
       * don't care that an invalid char is returned...)
       */
    watchdogReset();
  }

  ch = UART_UDR;
#endif

#if LED_DATA_FLASH
#if defined(__AVR_ATmega8__)    || defined(__AVR_ATmega8515__) || \
    defined(__AVR_ATmega8535__) || defined(__AVR_ATmega16__)   || \
    defined(__AVR_ATmega162__)  || defined(__AVR_ATmega32__)   || \
    defined(__AVR_ATmega64__)   || defined(__AVR_ATmega128__)
  LED_PORT ^= _BV(LED);
#else
  LED_PIN |= _BV(LED);
#endif
#endif

  return ch;
}

#if SOFT_UART
// AVR305 equation: #define UART_B_VALUE (((F_CPU/BAUD_RATE)-23)/6)
// Adding 3 to numerator simulates nearest rounding for more accurate baud rates
#define UART_B_VALUE (((F_CPU/BAUD_RATE)-20)/6)
#if UART_B_VALUE > 255
#error Baud rate too slow for soft UART
#endif

#if UART_B_VALUE < 6
// (this value is a "guess" at when loop/call overhead might become too
//  significant for the soft uart to work.  It tests OK with the popular
//  "ATtinycore" chips that need SOFT_UART, at the usual clock/baud combos.)
#error Baud rate too high for soft UART
#endif


void uartDelay() {
  __asm__ __volatile__ (
    "ldi r25,%[count]\n"
    "1:dec r25\n"
    "brne 1b\n"
    "ret\n"
    ::[count] "M" (UART_B_VALUE)
  );
}
#endif

void getNch(uint8_t count) {
  do getch(); while (--count);
  verifySpace();
}

void verifySpace() {
  if (getch() != CRC_EOP) {
    watchdogConfig(WATCHDOG_16MS);    // shorten WD timeout
    while (1)           // and busy-loop so that WD causes
      ;             //  a reset and app start.
  }
  putch(STK_INSYNC);
}

#if LED_START_FLASHES > 0
void flash_led(uint8_t count) {
  do {
    #if defined(__AVR_ATtiny261__)||defined(__AVR_ATtiny461__)||defined(__AVR_ATtiny861__) || defined(__AVR_ATtiny25__)||defined(__AVR_ATtiny45__)||defined(__AVR_ATtiny85__)
      TCNT1 = -(F_CPU/(8196*16));
      TIFR = _BV(TOV1);
      while(!(TIFR & _BV(TOV1)));
  #elif defined(__AVR_ATtiny43__)
      #error "LED flash for Tiny43 not yet supported"
  #else
      TCNT1 = -(F_CPU/(1024*16));
      TIFR1 = _BV(TOV1);
      while(!(TIFR1 & _BV(TOV1)));
  #endif
    
#if defined(__AVR_ATmega8__)    || defined(__AVR_ATmega8515__) || \
    defined(__AVR_ATmega8535__) || defined(__AVR_ATmega16__)   || \
    defined(__AVR_ATmega162__)  || defined(__AVR_ATmega32__)   || \
    defined(__AVR_ATmega64__)   || defined(__AVR_ATmega128__)
    LED_PORT ^= _BV(LED);
#else
    LED_PIN |= _BV(LED);
#endif
    watchdogReset();
#if (SOFT_UART == 0)
    /*
     * While in theory, the STK500 initial commands would be buffered
     *  by the UART hardware, avrdude sends several attempts in rather
     *  quick succession, some of which will be lost and cause us to
     *  get out of sync.  So if we see any data; stop blinking.
     */
#ifndef LIN_UART
    if (UART_SRA & _BV(RXC0))
#else
    if (LINSIR & _BV(LRXOK))
#endif
  break;
#else
// This doesn't seem to work?
//    if ((UART_PIN & (1<<UART_RX_BIT)) == 0)
//  break;  // detect start bit on soft uart too.
#endif
  } while (--count);
}
#endif

// Watchdog functions. These are only safe with interrupts turned off.
void watchdogReset() {
  __asm__ __volatile__ (
    "wdr\n"
  );
}

void watchdogConfig(uint8_t x) {
#ifdef WDCE //does it have a Watchdog Change Enable?
 #ifdef WDTCSR
  WDTCSR = _BV(WDCE) | _BV(WDE);
 #else
  WDTCR= _BV(WDCE) | _BV(WDE);
 #endif
#else //then it must be one of those newfangled ones that use CCP
  CCP=0xD8; //so write this magic number to CCP
#endif 

#ifdef WDTCSR
  WDTCSR = x;
#else
  WDTCR= x;
#endif
}


/*
 * void writebuffer(memtype, buffer, address, length)
 */
static inline void writebuffer(int8_t memtype, addr16_t mybuff,
             addr16_t address, pagelen_t len)
{
    switch (memtype) {
    case 'E': // EEPROM
#if SUPPORT_EEPROM || BIGBOOT
        while(len--) {
      eeprom_write_byte((address.bptr++), *(mybuff.bptr++));
        }
#else
  /*
   * On systems where EEPROM write is not supported, just busy-loop
   * until the WDT expires, which will eventually cause an error on
   * host system (which is what it should do.)
   */
  while (1)
      ; // Error: wait for WDT
#endif
  break;
    default:  // FLASH
  /*
   * Default to writing to Flash program memory.  By making this
   * the default rather than checking for the correct code, we save
   * space on chips that don't support any other memory types.
   */
  {
      // Copy buffer into programming buffer
      uint16_t addrPtr = address.word;

      /*
       * Start the page erase and wait for it to finish.  There
       * used to be code to do this while receiving the data over
       * the serial link, but the performance improvement was slight,
       * and we needed the space back.
       */
#ifdef FOURPAGEERASE
      if ((address.bytes[0] & ((SPM_PAGESIZE<<2)-1))==0) {
#endif
      __boot_page_erase_short(address.word);
      boot_spm_busy_wait();
#ifdef FOURPAGEERASE
      }
#endif

      /*
       * Copy data from the buffer into the flash write buffer.
       */
      do {
    __boot_page_fill_short((uint16_t)(void*)addrPtr, *(mybuff.wptr++));
    addrPtr += 2;
      } while (len -= 2);

      /*
       * Actually Write the buffer to flash (and wait for it to finish.)
       */
      __boot_page_write_short(address.word);
      boot_spm_busy_wait();
#if defined(RWWSRE)
      // Reenable read access to flash
      __boot_rww_enable_short();
#endif
  } // default block
  break;
    } // switch
}

static inline void read_mem(uint8_t memtype, addr16_t address, pagelen_t length)
{
    uint8_t ch;

    switch (memtype) {

#if SUPPORT_EEPROM || BIGBOOT
    case 'E': // EEPROM
  do {
      putch(eeprom_read_byte((address.bptr++)));
  } while (--length);
  break;
#endif
    default:
  do {
#ifdef VIRTUAL_BOOT_PARTITION
        // Undo vector patch in bottom page so verify passes
      if (address.word == rstVect0) ch = rstVect0_sav;
      else if (address.word == rstVect1) ch = rstVect1_sav;
      else if (address.word == saveVect0) ch = saveVect0_sav;
      else if (address.word == saveVect1) ch = saveVect1_sav;
      else ch = pgm_read_byte_near(address.bptr);
      address.bptr++;
#elif defined(RAMPZ)
      // Since RAMPZ should already be set, we need to use EPLM directly.
      // Also, we can use the autoincrement version of lpm to update "address"
      //      do putch(pgm_read_byte_near(address++));
      //      while (--length);
      // read a Flash and increment the address (may increment RAMPZ)
      __asm__ ("elpm %0,Z+\n" : "=r" (ch), "=z" (address.bptr): "1" (address));
#else
      // read a Flash byte and increment the address
      __asm__ ("lpm %0,Z+\n" : "=r" (ch), "=z" (address.bptr): "1" (address));
#endif
      putch(ch);
  } while (--length);
  break;
    } // switch
}


#if (APP_NOSPM == 0)

/*
 * Separate function for doing spm stuff
 * It's needed for application to do SPM, as SPM instruction works only
 * from bootloader.
 *
 * How it works:
 * - do SPM
 * - wait for SPM to complete
 * - if chip have RWW/NRWW sections it does additionaly:
 *   - if command is WRITE or ERASE, AND data=0 then reenable RWW section
 *
 * In short:
 * If you play erase-fill-write, just set data to 0 in ERASE and WRITE
 * If you are brave, you have your code just below bootloader in NRWW section
 *   you could do fill-erase-write sequence with data!=0 in ERASE and
 *   data=0 in WRITE
 */
static void do_spm(uint16_t address, uint8_t command, uint16_t data)  __attribute__ ((used));
static void do_spm(uint16_t address, uint8_t command, uint16_t data) {
    // Do spm stuff
    asm volatile (
  "    movw  r0, %3\n"
    "    __wr_spmcsr %0, %1\n"
    "    spm\n"
    "    clr  r1\n"
    :
    : "i" (_SFR_MEM_ADDR(__SPM_REG)),
        "r" ((uint8_t)command),
        "z" ((uint16_t)address),
        "r" ((uint16_t)data)
    : "r0"
    );

    // wait for spm to complete
    //   it doesn't have much sense for __BOOT_PAGE_FILL,
    //   but it doesn't hurt and saves some bytes on 'if'
    boot_spm_busy_wait();
#if defined(RWWSRE)
    // this 'if' condition should be: (command == __BOOT_PAGE_WRITE || command == __BOOT_PAGE_ERASE)...
    // but it's tweaked a little assuming that in every command we are interested in here, there
    // must be also SELFPRGEN set. If we skip checking this bit, we save here 4B
    if ((command & (_BV(PGWRT)|_BV(PGERS))) && (data == 0) ) {
      // Reenable read access to flash
      __boot_rww_enable_short();
    }
#endif
}
#endif



#if BIGBOOT
/*
 * Optiboot is designed to fit in 512 bytes, with a minimum feature set.
 * Some chips have a minimum bootloader size of 1024 bytes, and sometimes
 * it is desirable to add extra features even though 512bytes is exceedded.
 * In that case, the BIGBOOT can be used.
 * Our extra features so far don't come close to filling 1k, so we can
 * add extra "frivolous" data to the image.   In particular, we can add
 * information about how Optiboot was built (which options were selected,
 * what version, all in human-readable form (and extractable from the
 * binary with avr-strings.)
 * 
 * This can always be removed or trimmed if more actual program space
 * is needed in the future.  Currently the data occupies about 160 bytes,
 */
#define xstr(s) str(s)
#define str(s) #s
#define OPTFLASHSECT __attribute__((section(".fini8")))
#define OPT2FLASH(o) OPTFLASHSECT const char f##o[] = #o "=" xstr(o)


#if LED_START_FLASHES
OPT2FLASH(LED_START_FLASHES);
#endif
#if LED_DATA_FLASH
OPT2FLASH(LED_DATA_FLASH);
#endif
#if LED_START_ON
OPT2FLASH(LED_START_ON);
#endif
#ifdef LED_NAME
OPTFLASHSECT const char f_LED[] = "LED=" LED_NAME;
#endif

#if SUPPORT_EEPROM
OPT2FLASH(SUPPORT_EEPROM);
#endif
#if BAUD_RATE
OPT2FLASH(BAUD_RATE);
#endif
#if SOFT_UART
OPT2FLASH(SOFT_UART);
#endif
#if defined(UART)
OPT2FLASH(UART);
#endif

OPTFLASHSECT const char f_date[] = "Built:" __DATE__ ":" __TIME__;
#if BIGBOOT
OPT2FLASH(BIGBOOT);
#endif
#ifdef VIRTUAL_BOOT_PARTITION
OPTFLASHSECT const char f_boot[] = "Virtual_Boot_Partition";
#endif
OPT2FLASH(F_CPU);
OPTFLASHSECT const char f_device[] = "Device=" xstr(__AVR_DEVICE_NAME__);
#ifdef OPTIBOOT_CUSTOMVER
OPT2FLASH(OPTIBOOT_CUSTOMVER);
#endif
OPTFLASHSECT const char f_version[] = "Version=" xstr(OPTIBOOT_MAJVER) "." xstr(OPTIBOOT_MINVER);

#endif

вот что я добавил, 7 строк , начиная с  626 

#define FUNC_READ 1
#define FUNC_WRITE 1
/**********************************************************/
/* Optiboot bootloader for Arduino                        */
/*                                                        */
/* http://optiboot.googlecode.com                         */
/*                                                        */
/* Arduino-maintained version : See README.TXT            */
/* http://code.google.com/p/arduino/                      */
/*  It is the intent that changes not relevant to the     */
/*  Arduino production envionment get moved from the      */
/*  optiboot project to the arduino project in "lumps."   */
/*                                                        */
/* Heavily optimised bootloader that is faster and        */
/* smaller than the Arduino standard bootloader           */
/*                                                        */
/* Enhancements:                                          */
/*   Fits in 512 bytes, saving 1.5K of code space         */
/*   Higher baud rate speeds up programming               */
/*   Written almost entirely in C                         */
/*   Customisable timeout with accurate timeconstant      */
/*   Optional virtual UART. No hardware UART required.    */
/*   Optional virtual boot partition for devices without. */
/*                                                        */
/* What you lose:                                         */
/*   Implements a skeleton STK500 protocol which is       */
/*     missing several features including EEPROM          */
/*     programming and non-page-aligned writes            */
/*   High baud rate breaks compatibility with standard    */
/*     Arduino flash settings                             */
/*                                                        */
/* Fully supported:                                       */
/*   ATmega168 based devices  (Diecimila etc)             */
/*   ATmega328P based devices (Duemilanove etc)           */
/*                                                        */
/* Beta test (believed working.)                          */
/*   ATmega8 based devices (Arduino legacy)               */
/*   ATmega328 non-picopower devices                      */
/*   ATmega644P based devices (Sanguino)                  */
/*   ATmega1284P based devices                            */
/*   ATmega1280 based devices (Arduino Mega)              */
/*   ATmega2560 based devices (Arduino Mega)              */
/*                                                        */
/* Alpha test                                             */
/*   ATmega32                                             */
/*                                                        */
/* Work in progress:                                      */
/*   ATtiny84 based devices (Luminet)                     */
/*                                                        */
/* Does not support:                                      */
/*   USB based devices (eg. Teensy, Leonardo)             */
/*                                                        */
/* Assumptions:                                           */
/*   The code makes several assumptions that reduce the   */
/*   code size. They are all true after a hardware reset, */
/*   but may not be true if the bootloader is called by   */
/*   other means or on other hardware.                    */
/*     No interrupts can occur                            */
/*     UART and Timer 1 are set to their reset state      */
/*     SP points to RAMEND                                */
/*                                                        */
/* Code builds on code, libraries and optimisations from: */
/*   stk500boot.c          by Jason P. Kyle               */
/*   Arduino bootloader    http://arduino.cc              */
/*   Spiff's 1K bootloader http://spiffie.org/know/arduino_1k_bootloader/bootloader.shtml */
/*   avr-libc project      http://nongnu.org/avr-libc     */
/*   Adaboot               http://www.ladyada.net/library/arduino/bootloader.html */
/*   AVR305                Atmel Application Note         */
/*                                                        */

/* Copyright 2013-2015 by Bill Westfield.                 */
/* Copyright 2010 by Peter Knight.                        */
/*                                                        */
/* This program is free software; you can redistribute it */
/* and/or modify it under the terms of the GNU General    */
/* Public License as published by the Free Software       */
/* Foundation; either version 2 of the License, or        */
/* (at your option) any later version.                    */
/*                                                        */
/* This program is distributed in the hope that it will   */
/* be useful, but WITHOUT ANY WARRANTY; without even the  */
/* implied warranty of MERCHANTABILITY or FITNESS FOR A   */
/* PARTICULAR PURPOSE.  See the GNU General Public        */
/* License for more details.                              */
/*                                                        */
/* You should have received a copy of the GNU General     */
/* Public License along with this program; if not, write  */
/* to the Free Software Foundation, Inc.,                 */
/* 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA */
/*                                                        */
/* Licence can be viewed at                               */
/* http://www.fsf.org/licenses/gpl.txt                    */
/*                                                        */
/**********************************************************/


/**********************************************************/
/*                                                        */
/* Optional defines:                                      */
/*                                                        */
/**********************************************************/
/*                                                        */
/* BIGBOOT:                                              */
/* Build a 1k bootloader, not 512 bytes. This turns on    */
/* extra functionality.                                   */
/*                                                        */
/* BAUD_RATE:                                             */
/* Set bootloader baud rate.                              */
/*                                                        */
/* SOFT_UART:                                             */
/* Use AVR305 soft-UART instead of hardware UART.         */
/*                                                        */
/* LED_START_FLASHES:                                     */
/* Number of LED flashes on bootup.                       */
/*                                                        */
/* LED_DATA_FLASH:                                        */
/* Flash LED when transferring data. For boards without   */
/* TX or RX LEDs, or for people who like blinky lights.   */
/*                                                        */
/* SUPPORT_EEPROM:                                        */
/* Support reading and writing from EEPROM. This is not   */
/* used by Arduino, so off by default.                    */
/*                                                        */
/* WDTIME:                                                */
/* Bootloader timeout period, in seconds.                 */
/*  1 and 2 seconds are available on all chips            */
/*  4 and 8 are supported on most                         */
/*                                                        */
/* UART:                                                  */
/* UART number (0..n) for devices with more than          */
/* one hardware uart (644P, 1284P, etc)                   */
/*                                                        */
/**********************************************************/

/*
 * default values.
 */
#if !defined(BIGBOOT)
#  define BIGBOOT 0
#endif
#if !defined(SUPPORT_EEPROM)
#  define SUPPORT_EEPROM 0
#endif

#if !defined(SOFT_UART)
#  define SOFT_UART 0
#endif
#if !defined(UART)
#define UART 0
#endif
#if !defined(SINGLESPEED)
#define SINGLESPEED 0
#endif

#if !defined(APP_NOSPM)
#define APP_NOSPM 0
#endif

#if !defined(LED_START_FLASHES)
#define LED_START_FLASHES 0
#endif
#if !defined(LED_DATA_FLASH)
#  define LED_DATA_FLASH 0
#endif
#if !defined(LED_START_ON)
#  define LED_START_ON 0
#endif


/**********************************************************/
/* Version Numbers!                                       */
/*                                                        */
/* Arduino Optiboot now includes this Version number in   */
/* the source and object code.                            */
/*                                                        */
/* Version 3 was released as zip from the optiboot        */
/*  repository and was distributed with Arduino 0022.     */
/* Version 4 starts with the arduino repository commit    */
/*  that brought the arduino repository up-to-date with   */
/*  the optiboot source tree changes since v3.            */
/* Version 5 was created at the time of the new Makefile  */
/*  structure (Mar, 2013), even though no binaries changed*/
/* Version 6 added EEPROM support, including causing an   */
/*  error when trying to write eeprom with versions that  */
/*  didn't have the code there. Makefiles were further    */
/*  restructured.  Overlapping SPM/download removed.      */
/* Version 7 straightened out the MCUSR and RESET         */
/*  handling, did MORE Makefile mods.  EEPROM support now */
/*  fits in 512 bytes, if you turn off LED Blinking.      */
/*  Various bigboot and virboot targets were fixed.       */
/* Version 8.0 adds the do_spm code callable from Apps.   */
/*                                                        */
/* It would be good if versions implemented outside the   */
/*  official repository used an out-of-seqeunce version   */
/*  number (like 104.6 if based on based on 4.5) to       */
/*  prevent collisions.  The CUSTOM_VERSION=n option      */
/*  adds n to the high version to facilitate this.        */
/*                                                        */
/**********************************************************/

/**********************************************************/
/* Edit History:            */
/*                */
/* Aug 2019             */
/* 8.1  WestfW Fix bug in calculation of Vboot offset     */
/* Sep 2018             */
/* 8.0  WestfW (and Majekw and MCUDude)       */
/*      Include do_spm routine callable from the app      */
/*      at BOOTSTART+2, controllable with compile option  */
/* July 2018              */
/* 7.0  WestfW (with much input from Others)      */
/*  Fix MCUSR treatement as per much discussion,    */
/*   Patches by MarkG55, majekw.  Preserve value    */
/*   for the application, as much as possible.    */
/*   see https://github.com/Optiboot/optiboot/issues/97 */
/*  Optimize a bit by implementing a union for the    */
/*   various 16bit address values used (based on    */
/*   observation by "aweatherguy", but different.)    */
/*  Slightly optimize math in VIRTUAL_BOOT code   */
/*  Add some virboot targets, fix some fuses.   */
/*  Implement LED_START_ON; less code than flashes    */
/* Aug 2014             */
/* 6.2 WestfW: make size of length variables dependent    */
/*              on the SPM_PAGESIZE.  This saves space    */
/*              on the chips where it's most important.   */
/* 6.1 WestfW: Fix OPTIBOOT_CUSTOMVER (send it!)    */
/*             Make no-wait mod less picky about    */
/*               skipping the bootloader.     */
/*             Remove some dead code        */
/* Jun 2014             */
/* 6.0 WestfW: Modularize memory read/write functions   */
/*             Remove serial/flash overlap      */
/*              (and all references to NRWWSTART/etc)   */
/*             Correctly handle pagesize > 255bytes       */
/*             Add EEPROM support in BIGBOOT (1284)       */
/*             EEPROM write on small chips now causes err */
/*             Split Makefile into smaller pieces         */
/*             Add Wicked devices Wildfire      */
/*         Move UART=n conditionals into pin_defs.h   */
/*         Remove LUDICOUS_SPEED option     */
/*         Replace inline assembler for .version      */
/*              and add OPTIBOOT_CUSTOMVER for user code  */
/*             Fix LED value for Bobuino (Makefile)       */
/*             Make all functions explicitly inline or    */
/*              noinline, so we fit when using gcc4.8     */
/*             Change optimization options for gcc4.8   */
/*             Make ENV=arduino work in 1.5.x trees.    */
/* May 2014                                               */
/* 5.0 WestfW: Add support for 1Mbps UART                 */
/* Mar 2013                                               */
/* 5.0 WestfW: Major Makefile restructuring.              */
/*             See Makefile and pin_defs.h                */
/*             (no binary changes)                        */
/*                                                        */
/* 4.6 WestfW/Pito: Add ATmega32 support                  */
/* 4.6 WestfW/radoni: Don't set LED_PIN as an output if   */
/*                    not used. (LED_START_FLASHES = 0)   */
/* Jan 2013             */
/* 4.6 WestfW/dkinzer: use autoincrement lpm for read     */
/* 4.6 WestfW/dkinzer: pass reset cause to app in R2      */
/* Mar 2012                                               */
/* 4.5 WestfW: add infrastructure for non-zero UARTS.     */
/* 4.5 WestfW: fix SIGNATURE_2 for m644 (bad in avr-libc) */
/* Jan 2012:                                              */
/* 4.5 WestfW: fix NRWW value for m1284.                  */
/* 4.4 WestfW: use attribute OS_main instead of naked for */
/*             main().  This allows optimizations that we */
/*             count on, which are prohibited in naked    */
/*             functions due to PR42240.  (keeps us less  */
/*             than 512 bytes when compiler is gcc4.5     */
/*             (code from 4.3.2 remains the same.)        */
/* 4.4 WestfW and Maniacbug:  Add m1284 support.  This    */
/*             does not change the 328 binary, so the     */
/*             version number didn't change either. (?)   */
/* June 2011:                                             */
/* 4.4 WestfW: remove automatic soft_uart detect (didn't  */
/*             know what it was doing or why.)  Added a   */
/*             check of the calculated BRG value instead. */
/*             Version stays 4.4; existing binaries are   */
/*             not changed.                               */
/* 4.4 WestfW: add initialization of address to keep      */
/*             the compiler happy.  Change SC'ed targets. */
/*             Return the SW version via READ PARAM       */
/* 4.3 WestfW: catch framing errors in getch(), so that   */
/*             AVRISP works without HW kludges.           */
/*  http://code.google.com/p/arduino/issues/detail?id=368n*/
/* 4.2 WestfW: reduce code size, fix timeouts, change     */
/*             verifySpace to use WDT instead of appstart */
/* 4.1 WestfW: put version number in binary.      */
/**********************************************************/

#define OPTIBOOT_MAJVER 8
#define OPTIBOOT_MINVER 1

/*
 * OPTIBOOT_CUSTOMVER should be defined (by the makefile) for custom edits
 * of optiboot.  That way you don't wind up with very different code that
 * matches the version number of a "released" optiboot.
 */

#if !defined(OPTIBOOT_CUSTOMVER)
#define OPTIBOOT_CUSTOMVER 0
#endif

unsigned const int __attribute__((section(".version"))) 
optiboot_version = 256*(OPTIBOOT_MAJVER + OPTIBOOT_CUSTOMVER) + OPTIBOOT_MINVER;


#include <inttypes.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <avr/eeprom.h>

/*
 * optiboot uses several "address" variables that are sometimes byte pointers,
 * sometimes word pointers. sometimes 16bit quantities, and sometimes built
 * up from 8bit input characters.  avr-gcc is not great at optimizing the
 * assembly of larger words from bytes, but we can use the usual union to
 * do this manually.  Expanding it a little, we can also get rid of casts.
 */
typedef union {
  uint8_t  *bptr;
  uint16_t *wptr;
  uint16_t word;
  uint8_t bytes[2];
} addr16_t;

/*
 * Note that we use a replacement of "boot.h"
 * <avr/boot.h> uses sts instructions, but this version uses out instructions
 * This saves cycles and program memory, if possible.
 * boot_opt.h pulls in the standard boot.h for the odd target (?)
 */
#include "boot_opt.h"


// We don't use <avr/wdt.h> as those routines have interrupt overhead we don't need.

/*
 * pin_defs.h
 * This contains most of the rather ugly defines that implement our
 * ability to use UART=n and LED=D3, and some avr family bit name differences.
 */
#include "pin_defs.h"

/*
 * stk500.h contains the constant definitions for the stk500v1 comm protocol
 */
#include "stk500.h"

/* set the UART baud rate defaults */
#ifndef BAUD_RATE
#if F_CPU >= 8000000L
#define BAUD_RATE   115200L // Highest rate Avrdude win32 will support
#elif F_CPU >= 1000000L
#define BAUD_RATE   9600L   // 19200 also supported, but with significant error
#elif F_CPU >= 128000L
#define BAUD_RATE   4800L   // Good for 128kHz internal RC
#else
#define BAUD_RATE 1200L     // Good even at 32768Hz
#endif
#endif

#if (SOFT_UART == 0)
#if SINGLESPEED
/* Single speed option */
#define BAUD_SETTING (( (F_CPU + BAUD_RATE * 8L) / ((BAUD_RATE * 16L))) - 1 )
#define BAUD_ACTUAL (F_CPU/(16 * ((BAUD_SETTING)+1)))
#else
/* Normal U2X usage */
#define BAUD_SETTING (( (F_CPU + BAUD_RATE * 4L) / ((BAUD_RATE * 8L))) - 1 )
#define BAUD_ACTUAL (F_CPU/(8 * ((BAUD_SETTING)+1)))
#endif
#if BAUD_ACTUAL <= BAUD_RATE
  #define BAUD_ERROR (( 100*(BAUD_RATE - BAUD_ACTUAL) ) / BAUD_RATE)
  #if BAUD_ERROR >= 5
    #error BAUD_RATE off by greater than -5%
  #elif BAUD_ERROR >= 2  && !defined(PRODUCTION)
    #warning BAUD_RATE off by greater than -2%
  #endif
#else
  #define BAUD_ERROR (( 100*(BAUD_ACTUAL - BAUD_RATE) ) / BAUD_RATE)
  #if BAUD_ERROR >= 5
    #error BAUD_RATE off by greater than 5%
  #elif BAUD_ERROR >= 2  && !defined(PRODUCTION)
    #warning BAUD_RATE off by greater than 2%
  #endif
#endif

#if BAUD_SETTING > 250
#error Unachievable baud rate (too slow) BAUD_RATE 
#endif // baud rate slow check
#if (BAUD_SETTING - 1) < 3
#if BAUD_ERROR != 0 // permit high bitrates (ie 1Mbps@16MHz) if error is zero
#error Unachievable baud rate (too fast) BAUD_RATE 
#endif
#endif // baud rate fast check
#endif // SOFT_UART

/* Watchdog settings */
#define WATCHDOG_OFF    (0)
#define WATCHDOG_16MS   (_BV(WDE))
#define WATCHDOG_32MS   (_BV(WDP0) | _BV(WDE))
#define WATCHDOG_64MS   (_BV(WDP1) | _BV(WDE))
#define WATCHDOG_125MS  (_BV(WDP1) | _BV(WDP0) | _BV(WDE))
#define WATCHDOG_250MS  (_BV(WDP2) | _BV(WDE))
#define WATCHDOG_500MS  (_BV(WDP2) | _BV(WDP0) | _BV(WDE))
#define WATCHDOG_1S     (_BV(WDP2) | _BV(WDP1) | _BV(WDE))
#define WATCHDOG_2S     (_BV(WDP2) | _BV(WDP1) | _BV(WDP0) | _BV(WDE))
#ifdef  WDP3
#define WATCHDOG_4S     (_BV(WDP3) | _BV(WDE))
#define WATCHDOG_8S     (_BV(WDP3) | _BV(WDP0) | _BV(WDE))
#endif

/*
 * Watchdog timeout translations from human readable to config vals
 */
#ifndef WDTTIME
# define WDTPERIOD WATCHDOG_1S  // 1 second default
#elif WDTTIME == 1
# define WDTPERIOD WATCHDOG_1S  // 1 second
#elif WDTTIME == 2
# define WDTPERIOD WATCHDOG_2S  // 2 seconds
#elif defined(WDP3) && (WDTTIME == 4)
# define WDTPERIOD WATCHDOG_4S  // 4 seconds
#elif defined(WDP3) && (WDTTIME == 8)
# define WDTPERIOD WATCHDOG_8S  // 8 seconds
#else
#error Invalid TIMEOUT
#endif

/*
 * We can never load flash with more than 1 page at a time, so we can save
 * some code space on parts with smaller pagesize by using a smaller int.
 */
#if SPM_PAGESIZE > 255
typedef uint16_t pagelen_t ;
#define GETLENGTH(len) len = getch()<<8; len |= getch()
#else
typedef uint8_t pagelen_t;
#define GETLENGTH(len) (void) getch() /* skip high byte */; len = getch()
#endif


/* Function Prototypes
 * The main() function is in init9, which removes the interrupt vector table
 * we don't need. It is also 'OS_main', which means the compiler does not
 * generate any entry or exit code itself (but unlike 'naked', it doesn't
 * supress some compile-time options we want.)
 */

void pre_main(void) __attribute__ ((naked)) __attribute__ ((section (".init8")));
int main(void) __attribute__ ((OS_main)) __attribute__ ((section (".init9"))) __attribute__((used));

void __attribute__((noinline)) __attribute__((leaf)) putch(char);
uint8_t __attribute__((noinline)) __attribute__((leaf)) getch(void) ;
void __attribute__((noinline)) verifySpace();
void __attribute__((noinline)) watchdogConfig(uint8_t x);

static void getNch(uint8_t);
#if LED_START_FLASHES > 0
static inline void flash_led(uint8_t);
#endif
static inline void watchdogReset();
static inline void writebuffer(int8_t memtype, addr16_t mybuff,
             addr16_t address, pagelen_t len);
static inline void read_mem(uint8_t memtype,
          addr16_t, pagelen_t len);

#ifdef SOFT_UART
void uartDelay() __attribute__ ((naked));
#endif

/*
 * RAMSTART should be self-explanatory.  It's bigger on parts with a
 * lot of peripheral registers.  Let 0x100 be the default
 * Note that RAMSTART (for optiboot) need not be exactly at the start of RAM.
 */
#if !defined(RAMSTART)  // newer versions of gcc avr-libc define RAMSTART
#define RAMSTART 0x100
#if defined (__AVR_ATmega644P__)
// correct for a bug in avr-libc
#undef SIGNATURE_2
#define SIGNATURE_2 0x0A
#elif defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
#undef RAMSTART
#define RAMSTART (0x200)
#endif
#endif

/* C zero initialises all global variables. However, that requires */
/* These definitions are NOT zero initialised, but that doesn't matter */
/* This allows us to drop the zero init code, saving us memory */
static addr16_t buff = {(uint8_t *)(RAMSTART)};

/* Virtual boot partition support */
#ifdef VIRTUAL_BOOT_PARTITION

// RAM locations to save vector info (temporarilly)
#define rstVect0_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+4))
#define rstVect1_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+5))
#define saveVect0_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+6))
#define saveVect1_sav (*(uint8_t*)(RAMSTART+SPM_PAGESIZE*2+7))

#define RSTVEC_ADDRESS 0  // flash address where vectors start.
// Vector to save original reset jump:
//   SPM Ready is least probably used, so it's default
//   if not, use old way WDT_vect_num,
//   or simply set custom save_vect_num in Makefile using vector name
//   or even raw number.
#if !defined (save_vect_num)
#if defined (SPM_RDY_vect_num)
#define save_vect_num (SPM_RDY_vect_num)
#elif defined (SPM_READY_vect_num)
#define save_vect_num (SPM_READY_vect_num)
#elif defined (EE_RDY_vect_num)
#define save_vect_num (EE_RDY_vect_num)
#elif defined (EE_READY_vect_num)
#define save_vect_num (EE_READY_vect_num)
#elif defined (WDT_vect_num)
#define save_vect_num (WDT_vect_num)
#else
#error Cant find SPM or WDT interrupt vector for this CPU
#endif
#endif //save_vect_num

// check if it's on the same page (code assumes that)

#if FLASHEND > 8192
// AVRs with more than 8k of flash have 4-byte vectors, and use jmp.
//  We save only 16 bits of address, so devices with more than 128KB
//  may behave wrong for upper part of address space.
#define rstVect0 2
#define rstVect1 3
#define saveVect0 (save_vect_num*4+2)
#define saveVect1 (save_vect_num*4+3)
#define appstart_vec (save_vect_num*2)

// address of page that will have the saved vector
#define SAVVEC_ADDRESS (SPM_PAGESIZE*(save_vect_num/(SPM_PAGESIZE/4)))

#else

// AVRs with up to 8k of flash have 2-byte vectors, and use rjmp.
#define rstVect0 0
#define rstVect1 1
#define saveVect0 (save_vect_num*2)
#define saveVect1 (save_vect_num*2+1)
#define appstart_vec (save_vect_num)

// address of page that will have the saved vector
#define SAVVEC_ADDRESS (SPM_PAGESIZE*(save_vect_num/(SPM_PAGESIZE/2)))
#endif

#else

#define appstart_vec (0)

#endif // VIRTUAL_BOOT_PARTITION


/* everything that needs to run VERY early */
void pre_main(void) {
  // Allow convenient way of calling do_spm function - jump table,
  //   so entry to this function will always be here, indepedent of compilation,
  //   features etc
  asm volatile (
    " rjmp  1f\n"
#if APP_NOSPM
    "   ret\n"   // if do_spm isn't include, return without doing anything
#else
    " rjmp  do_spm\n"
#endif
    "1:\n"
  );
}


/* main program starts here */
int main(void) {
  uint8_t ch;

  /*
   * Making these local and in registers prevents the need for initializing
   * them, and also saves space because code no longer stores to memory.
   * (initializing address keeps the compiler happy, but isn't really
   *  necessary, and uses 4 bytes of flash.)
   */
  register addr16_t address;
  register pagelen_t  length;

  // After the zero init loop, this is the first code to run.
  //
  // This code makes the following assumptions:
  //  No interrupts will execute
  //  SP points to RAMEND
  //  r1 contains zero
  //
  // If not, uncomment the following instructions:
  // cli();
  asm volatile ("clr __zero_reg__");

#if defined(__AVR_ATmega8__) || defined(__AVR_ATmega8515__) ||    \
    defined(__AVR_ATmega8535__) || defined (__AVR_ATmega16__) ||  \
    defined (__AVR_ATmega32__) || defined (__AVR_ATmega64__)  ||  \
    defined (__AVR_ATmega128__) || defined (__AVR_ATmega162__)
  SP=RAMEND;  // This is done by hardware reset
#endif

#if defined(OSCCAL_VALUE)
  OSCCAL = OSCCAL_VALUE;
#endif

  /*
   * Protect as much from MCUSR as possible for application
   * and still skip bootloader if not necessary
   * 
   * Code by MarkG55
   * see discusion in https://github.com/Optiboot/optiboot/issues/97
   */
#if defined(__AVR_ATmega8515__) || defined(__AVR_ATmega8535__) || \
    defined(__AVR_ATmega16__)   || defined(__AVR_ATmega162__) ||  \
    defined (__AVR_ATmega128__)
  ch = MCUCSR;
#else

if (!eeprom_read_byte((uint8_t*)254))
{
eeprom_write_byte((uint8_t*)254, 0xFF);
MCUSR = ~(_BV(WDRF));
ch=2;
}
else ch = MCUSR;
#endif
  // Skip all logic and run bootloader if MCUSR is cleared (application request)
  if (ch != 0) {
      /*
       * To run the boot loader, External Reset Flag must be set.
       * If not, we could make shortcut and jump directly to application code.
       * Also WDRF set with EXTRF is a result of Optiboot timeout, so we
       * shouldn't run bootloader in loop :-) That's why:
       *  1. application is running if WDRF is cleared
       *  2. we clear WDRF if it's set with EXTRF to avoid loops
       * One problematic scenario: broken application code sets watchdog timer 
       * without clearing MCUSR before and triggers it quickly. But it's
       * recoverable by power-on with pushed reset button.
       */
      if ((ch & (_BV(WDRF) | _BV(EXTRF))) != _BV(EXTRF)) { 
    if (ch & _BV(EXTRF)) {
        /*
         * Clear WDRF because it was most probably set by wdr in bootloader.
         * It's also needed to avoid loop by broken application which could
         * prevent entering bootloader.
         * '&' operation is skipped to spare few bytes as bits in MCUSR
         * can only be cleared.
         */
#if defined(__AVR_ATmega8515__) || defined(__AVR_ATmega8535__) || \
    defined(__AVR_ATmega16__)   || defined(__AVR_ATmega162__) ||  \
    defined(__AVR_ATmega128__)
               // Fix missing definitions in avr-libc
        MCUCSR = ~(_BV(WDRF));
#else
        MCUSR = ~(_BV(WDRF));
#endif
    }
    /* 
     * save the reset flags in the designated register
     * This can be saved in a main program by putting code in .init0 (which
     * executes before normal c init code) to save R2 to a global variable.
     */
    __asm__ __volatile__ ("mov r2, %0\n" :: "r" (ch));

    // switch off watchdog
    watchdogConfig(WATCHDOG_OFF);
    // Note that appstart_vec is defined so that this works with either
    // real or virtual boot partitions.
     __asm__ __volatile__ (
      // Jump to 'save' or RST vector
#ifdef VIRTUAL_BOOT_PARTITION
      // full code version for virtual boot partition
      "ldi r30,%[rstvec]\n"
      "clr r31\n"
      "ijmp\n"::[rstvec] "M"(appstart_vec)
#else
#ifdef RAMPZ
      // use absolute jump for devices with lot of flash
      "jmp 0\n"::
#else
      // use rjmp to go around end of flash to address 0
      // it uses fact that optiboot_version constant is 2 bytes before end of flash
      "rjmp optiboot_version+2\n"
#endif //RAMPZ
#endif //VIRTUAL_BOOT_PARTITION
    );
      }
  }

#if LED_START_FLASHES > 0
  // Set up Timer 1 for timeout counter
#if defined(__AVR_ATtiny261__)||defined(__AVR_ATtiny461__)||defined(__AVR_ATtiny861__)
  TCCR1B = 0x0E; //div 8196 - we could divide by less since it's a 10-bit counter, but why? 
#elif defined(__AVR_ATtiny25__)||defined(__AVR_ATtiny45__)||defined(__AVR_ATtiny85__)
  TCCR1 = 0x0E; //div 8196 - it's an 8-bit timer. 
#elif defined(__AVR_ATtiny43__)
  #error "LED flash for Tiny43 not yet supported"
#else
  TCCR1B = _BV(CS12) | _BV(CS10); // div 1024
#endif
#endif


#if (SOFT_UART == 0)
  #if defined(__AVR_ATmega8__) || defined (__AVR_ATmega8515__) || \
      defined (__AVR_ATmega8535__) || defined (__AVR_ATmega16__) || \
      defined (__AVR_ATmega32__)
#if (SINGLESPEED == 0)
  UCSRA = _BV(U2X); //Double speed mode USART
  #endif //singlespeed
  UCSRB = _BV(RXEN) | _BV(TXEN);  // enable Rx & Tx
  UCSRC = _BV(URSEL) | _BV(UCSZ1) | _BV(UCSZ0);  // config USART; 8N1
  UBRRL = (uint8_t)BAUD_SETTING;
  #else // mega8/etc
    #ifdef LIN_UART
  //DDRB|=3;
  LINCR = (1 << LSWRES); 
  //LINBRRL = (((F_CPU * 10L / 32L / BAUD_RATE) + 5L) / 10L) - 1; 
  LINBRRL=(uint8_t)BAUD_SETTING;
  LINBTR = (1 << LDISR) | (8 << LBT0); 
  LINCR = _BV(LENA) | _BV(LCMD2) | _BV(LCMD1) | _BV(LCMD0); 
  LINDAT=0;
    #else
      #if (SINGLESPEED == 0)
  UART_SRA = _BV(U2X0); //Double speed mode USART0
      #endif
  UART_SRB = _BV(RXEN0) | _BV(TXEN0);
  UART_SRC = _BV(UCSZ00) | _BV(UCSZ01);
  UART_SRL = (uint8_t)BAUD_SETTING;
    #endif // LIN_UART
  #endif // mega8/etc
#endif // soft_uart

  // Set up watchdog to trigger after desired timeout
  watchdogConfig(WDTPERIOD);

#if (LED_START_FLASHES > 0) || LED_DATA_FLASH || LED_START_ON
  /* Set LED pin as output */
  LED_DDR |= _BV(LED);
#endif

#if SOFT_UART
  /* Set TX pin as output */
  UART_DDR |= _BV(UART_TX_BIT);
#endif

#if LED_START_FLASHES > 0
  /* Flash onboard LED to signal entering of bootloader */
  flash_led(LED_START_FLASHES * 2);
#else
#if LED_START_ON
  /* Turn on LED to indicate starting bootloader (less code!) */
  LED_PORT |= _BV(LED);
#endif
#endif

  /* Forever loop: exits by causing WDT reset */
  for (;;) {
    /* get character from UART */
    ch = getch();

    if(ch == STK_GET_PARAMETER) {
      unsigned char which = getch();
      verifySpace();
      /*
       * Send optiboot version as "SW version"
       * Note that the references to memory are optimized away.
       */
      if (which == STK_SW_MINOR) {
    putch(optiboot_version & 0xFF);
      } else if (which == STK_SW_MAJOR) {
    putch(optiboot_version >> 8);
      } else {
  /*
   * GET PARAMETER returns a generic 0x03 reply for
         * other parameters - enough to keep Avrdude happy
   */
  putch(0x03);
      }
    }
    else if(ch == STK_SET_DEVICE) {
      // SET DEVICE is ignored
      getNch(20);
    }
    else if(ch == STK_SET_DEVICE_EXT) {
      // SET DEVICE EXT is ignored
      getNch(5);
    }
    else if(ch == STK_LOAD_ADDRESS) {
      // LOAD ADDRESS
      address.bytes[0] = getch();
      address.bytes[1] = getch();
#ifdef RAMPZ
      // Transfer top bit to LSB in RAMPZ
      if (address.bytes[1] & 0x80) {
        RAMPZ |= 0x01;
      }
      else {
        RAMPZ &= 0xFE;
      }
#endif
      address.word *= 2; // Convert from word address to byte address
      verifySpace();
    }
    else if(ch == STK_UNIVERSAL) {
#ifdef RAMPZ
      // LOAD_EXTENDED_ADDRESS is needed in STK_UNIVERSAL for addressing more than 128kB
      if ( AVR_OP_LOAD_EXT_ADDR == getch() ) {
        // get address
        getch();  // get '0'
        RAMPZ = (RAMPZ & 0x01) | ((getch() << 1) & 0xff);  // get address and put it in RAMPZ
        getNch(1); // get last '0'
        // response
        putch(0x00);
      }
      else {
        // everything else is ignored
        getNch(3);
        putch(0x00);
      }
#else
      // UNIVERSAL command is ignored
      getNch(4);
      putch(0x00);
#endif
    }
    /* Write memory, length is big endian and is in bytes */
    else if(ch == STK_PROG_PAGE) {
      // PROGRAM PAGE - we support flash programming only, not EEPROM
      uint8_t desttype;
      uint8_t *bufPtr;
      pagelen_t savelength;

      GETLENGTH(length);
      savelength = length;
      desttype = getch();

      // read a page worth of contents
      bufPtr = buff.bptr;
      do *bufPtr++ = getch();
      while (--length);

      // Read command terminator, start reply
      verifySpace();

#ifdef VIRTUAL_BOOT_PARTITION
/*
 *              How the Virtual Boot Partition works:
 * At the beginning of a normal AVR program are a set of vectors that
 * implement the interrupt mechanism.  Each vector is usually a single
 * instruction that dispatches to the appropriate ISR.
 * The instruction is normally an rjmp (on AVRs with 8k or less of flash)
 * or jmp instruction, and the 0th vector is executed on reset and jumps
 * to the start of the user program:
 * vectors: jmp startup
 *          jmp ISR1
 *          jmp ISR2
 *             :      ;; etc
 *          jmp lastvector
 * To implement the "Virtual Boot Partition", Optiboot detects when the
 * flash page containing the vectors is being programmed, and replaces the
 * startup vector with a jump to te beginning of Optiboot.  Then it saves
 * the applications's startup vector in another (must be unused by the
 * application), and finally programs the page with the changed vectors.
 * Thereafter, on reset, the vector will dispatch to the beginning of
 * Optiboot.  When Optiboot decides that it will run the user application,
 * it fetches the saved start address from the unused vector, and jumps
 * there.
 * The logic is dependent on size of flash, and whether the reset vector is
 * on the same flash page as the saved start address.
 */

#if FLASHEND > 8192
/*
 * AVR with 4-byte ISR Vectors and "jmp"
 * WARNING: this works only up to 128KB flash!
 */
#if FLASHEND > (128*1024)
#error "Can't use VIRTUAL_BOOT_PARTITION with more than 128k of Flash"
#endif
      if (address.word == RSTVEC_ADDRESS) {
  // This is the reset vector page. We need to live-patch the
  // code so the bootloader runs first.
  //
  // Save jmp targets (for "Verify")
  rstVect0_sav = buff.bptr[rstVect0];
  rstVect1_sav = buff.bptr[rstVect1];

        // Add "jump to Optiboot" at RESET vector
        // WARNING: this works as long as 'main' is in first section
        buff.bptr[rstVect0] = ((uint16_t)pre_main) & 0xFF;
        buff.bptr[rstVect1] = ((uint16_t)pre_main) >> 8;

#if (SAVVEC_ADDRESS != RSTVEC_ADDRESS)
// the save_vector is not necessarilly on the same flash page as the reset
//  vector.  If it isn't, we've waiting to actually write it.
      } else if (address.word == SAVVEC_ADDRESS) {
    // Save old values for Verify
    saveVect0_sav = buff.bptr[saveVect0 - SAVVEC_ADDRESS];
    saveVect1_sav = buff.bptr[saveVect1 - SAVVEC_ADDRESS];

    // Move RESET jmp target to 'save' vector
    buff.bptr[saveVect0 - SAVVEC_ADDRESS] = rstVect0_sav;
    buff.bptr[saveVect1 - SAVVEC_ADDRESS] = rstVect1_sav;
      }
#else 
        // Save old values for Verify
        saveVect0_sav = buff.bptr[saveVect0];
  saveVect1_sav = buff.bptr[saveVect1];

        // Move RESET jmp target to 'save' vector
        buff.bptr[saveVect0] = rstVect0_sav;
        buff.bptr[saveVect1] = rstVect1_sav;
    }
#endif

#else
/*
 * AVR with 2-byte ISR Vectors and rjmp
 */
      if (address.word == rstVect0) {
        // This is the reset vector page. We need to live-patch
        // the code so the bootloader runs first.
        //
        // Move RESET vector to 'save' vector
  // Save jmp targets (for "Verify")
  rstVect0_sav = buff.bptr[rstVect0];
  rstVect1_sav = buff.bptr[rstVect1];
  addr16_t vect;
  vect.word = ((uint16_t)pre_main-1);
  // Instruction is a relative jump (rjmp), so recalculate.
  // an RJMP instruction is 0b1100xxxx xxxxxxxx, so we should be able to
  // do math on the offsets without masking it off first.
  // Note that rjmp is relative to the already incremented PC, so the
  //  offset is one less than you might expect.
  buff.bptr[0] = vect.bytes[0]; // rjmp to start of bootloader
  buff.bptr[1] = vect.bytes[1] | 0xC0;  // make an "rjmp"
#if (SAVVEC_ADDRESS != RSTVEC_ADDRESS)
      } else if (address.word == SAVVEC_ADDRESS) {
  addr16_t vect;
  vect.bytes[0] = rstVect0_sav;
  vect.bytes[1] = rstVect1_sav;
  // Save old values for Verify
  saveVect0_sav = buff.bptr[saveVect0 - SAVVEC_ADDRESS];
  saveVect1_sav = buff.bptr[saveVect1 - SAVVEC_ADDRESS];

  vect.word = (vect.word-save_vect_num); //substract 'save' interrupt position
        // Move RESET jmp target to 'save' vector
        buff.bptr[saveVect0 - SAVVEC_ADDRESS] = vect.bytes[0];
        buff.bptr[saveVect1 - SAVVEC_ADDRESS] = (vect.bytes[1] & 0x0F)| 0xC0;  // make an "rjmp"
      }
#else

      // Save old values for Verify
      saveVect0_sav = buff.bptr[saveVect0];
      saveVect1_sav = buff.bptr[saveVect1];

      vect.bytes[0] = rstVect0_sav;
      vect.bytes[1] = rstVect1_sav;
      vect.word = (vect.word-save_vect_num); //substract 'save' interrupt position
      // Move RESET jmp target to 'save' vector
      buff.bptr[saveVect0] = vect.bytes[0];
      buff.bptr[saveVect1] = (vect.bytes[1] & 0x0F)| 0xC0;  // make an "rjmp"
      // Add rjmp to bootloader at RESET vector
      vect.word = ((uint16_t)pre_main-1); // (main) is always <= 0x0FFF; no masking needed.
      buff.bptr[0] = vect.bytes[0]; // rjmp 0x1c00 instruction
  }
  
#endif

#endif // FLASHEND
#endif // VBP

      writebuffer(desttype, buff, address, savelength);


    }
    /* Read memory block mode, length is big endian.  */
    else if(ch == STK_READ_PAGE) {
      uint8_t desttype;
      GETLENGTH(length);

      desttype = getch();

      verifySpace();

      read_mem(desttype, address, length);
    }

    /* Get device signature bytes  */
    else if(ch == STK_READ_SIGN) {
      // READ SIGN - return what Avrdude wants to hear
      verifySpace();
      putch(SIGNATURE_0);
      putch(SIGNATURE_1);
      putch(SIGNATURE_2);
    }
    else if (ch == STK_LEAVE_PROGMODE) { /* 'Q' */
      // Adaboot no-wait mod
      watchdogConfig(WATCHDOG_16MS);
      verifySpace();
    }
    else {
      // This covers the response to commands like STK_ENTER_PROGMODE
      verifySpace();
    }
    putch(STK_OK);
  }
}

void putch(char ch) {
#if (SOFT_UART == 0)
  #ifndef LIN_UART
    while (!(UART_SRA & _BV(UDRE0))) {  /* Spin */ }
  #else
    while (!(LINSIR & _BV(LTXOK)))   {  /* Spin */ }
  #endif

  UART_UDR = ch;

#else
  __asm__ __volatile__ (
    "   com %[ch]\n" // ones complement, carry set
    "   sec\n"
    "1: brcc 2f\n"
    "   cbi %[uartPort],%[uartBit]\n"
    "   rjmp 3f\n"
    "2: sbi %[uartPort],%[uartBit]\n"
    "   nop\n"
    "3: rcall uartDelay\n"
    "   rcall uartDelay\n"
    "   lsr %[ch]\n"
    "   dec %[bitcnt]\n"
    "   brne 1b\n"
    :
    :
      [bitcnt] "d" (10),
      [ch] "r" (ch),
      [uartPort] "I" (_SFR_IO_ADDR(UART_PORT)),
      [uartBit] "I" (UART_TX_BIT)
    :
      "r25"
  );
#endif
}

uint8_t getch(void) {
  uint8_t ch;

#if LED_DATA_FLASH
#if defined(__AVR_ATmega8__)    || defined(__AVR_ATmega8515__) || \
    defined(__AVR_ATmega8535__) || defined(__AVR_ATmega16__)   || \
    defined(__AVR_ATmega162__)  || defined(__AVR_ATmega32__)   || \
    defined(__AVR_ATmega64__)   || defined(__AVR_ATmega128__)
  LED_PORT ^= _BV(LED);
#else
  LED_PIN |= _BV(LED);
#endif
#endif

#if SOFT_UART
    watchdogReset();
  __asm__ __volatile__ (
    "1: sbic  %[uartPin],%[uartBit]\n"  // Wait for start edge
    "   rjmp  1b\n"
    "   rcall uartDelay\n"          // Get to middle of start bit
    "2: rcall uartDelay\n"              // Wait 1 bit period
    "   rcall uartDelay\n"              // Wait 1 bit period
    "   clc\n"
    "   sbic  %[uartPin],%[uartBit]\n"
    "   sec\n"
    "   dec   %[bitCnt]\n"
    "   breq  3f\n"
    "   ror   %[ch]\n"
    "   rjmp  2b\n"
    "3:\n"
    :
      [ch] "=r" (ch)
    :
      [bitCnt] "d" (9),
      [uartPin] "I" (_SFR_IO_ADDR(UART_PIN)),
      [uartBit] "I" (UART_RX_BIT)
    :
      "r25"
);
#else
#ifndef LIN_UART
  while(!(UART_SRA & _BV(RXC0)))  {  /* Spin */ }
  if (!(UART_SRA & _BV(FE0))) {
#else
  while(!(LINSIR & _BV(LRXOK)))  {  /* Spin */ }
  if (!(LINSIR & _BV(LFERR))) {
#endif
      /*
       * A Framing Error indicates (probably) that something is talking
       * to us at the wrong bit rate.  Assume that this is because it
       * expects to be talking to the application, and DON'T reset the
       * watchdog.  This should cause the bootloader to abort and run
       * the application "soon", if it keeps happening.  (Note that we
       * don't care that an invalid char is returned...)
       */
    watchdogReset();
  }

  ch = UART_UDR;
#endif

#if LED_DATA_FLASH
#if defined(__AVR_ATmega8__)    || defined(__AVR_ATmega8515__) || \
    defined(__AVR_ATmega8535__) || defined(__AVR_ATmega16__)   || \
    defined(__AVR_ATmega162__)  || defined(__AVR_ATmega32__)   || \
    defined(__AVR_ATmega64__)   || defined(__AVR_ATmega128__)
  LED_PORT ^= _BV(LED);
#else
  LED_PIN |= _BV(LED);
#endif
#endif

  return ch;
}

#if SOFT_UART
// AVR305 equation: #define UART_B_VALUE (((F_CPU/BAUD_RATE)-23)/6)
// Adding 3 to numerator simulates nearest rounding for more accurate baud rates
#define UART_B_VALUE (((F_CPU/BAUD_RATE)-20)/6)
#if UART_B_VALUE > 255
#error Baud rate too slow for soft UART
#endif

#if UART_B_VALUE < 6
// (this value is a "guess" at when loop/call overhead might become too
//  significant for the soft uart to work.  It tests OK with the popular
//  "ATtinycore" chips that need SOFT_UART, at the usual clock/baud combos.)
#error Baud rate too high for soft UART
#endif


void uartDelay() {
  __asm__ __volatile__ (
    "ldi r25,%[count]\n"
    "1:dec r25\n"
    "brne 1b\n"
    "ret\n"
    ::[count] "M" (UART_B_VALUE)
  );
}
#endif

void getNch(uint8_t count) {
  do getch(); while (--count);
  verifySpace();
}

void verifySpace() {
  if (getch() != CRC_EOP) {
    watchdogConfig(WATCHDOG_16MS);    // shorten WD timeout
    while (1)           // and busy-loop so that WD causes
      ;             //  a reset and app start.
  }
  putch(STK_INSYNC);
}

#if LED_START_FLASHES > 0
void flash_led(uint8_t count) {
  do {
    #if defined(__AVR_ATtiny261__)||defined(__AVR_ATtiny461__)||defined(__AVR_ATtiny861__) || defined(__AVR_ATtiny25__)||defined(__AVR_ATtiny45__)||defined(__AVR_ATtiny85__)
      TCNT1 = -(F_CPU/(8196*16));
      TIFR = _BV(TOV1);
      while(!(TIFR & _BV(TOV1)));
  #elif defined(__AVR_ATtiny43__)
      #error "LED flash for Tiny43 not yet supported"
  #else
      TCNT1 = -(F_CPU/(1024*16));
      TIFR1 = _BV(TOV1);
      while(!(TIFR1 & _BV(TOV1)));
  #endif
    
#if defined(__AVR_ATmega8__)    || defined(__AVR_ATmega8515__) || \
    defined(__AVR_ATmega8535__) || defined(__AVR_ATmega16__)   || \
    defined(__AVR_ATmega162__)  || defined(__AVR_ATmega32__)   || \
    defined(__AVR_ATmega64__)   || defined(__AVR_ATmega128__)
    LED_PORT ^= _BV(LED);
#else
    LED_PIN |= _BV(LED);
#endif
    watchdogReset();
#if (SOFT_UART == 0)
    /*
     * While in theory, the STK500 initial commands would be buffered
     *  by the UART hardware, avrdude sends several attempts in rather
     *  quick succession, some of which will be lost and cause us to
     *  get out of sync.  So if we see any data; stop blinking.
     */
#ifndef LIN_UART
    if (UART_SRA & _BV(RXC0))
#else
    if (LINSIR & _BV(LRXOK))
#endif
  break;
#else
// This doesn't seem to work?
//    if ((UART_PIN & (1<<UART_RX_BIT)) == 0)
//  break;  // detect start bit on soft uart too.
#endif
  } while (--count);
}
#endif

// Watchdog functions. These are only safe with interrupts turned off.
void watchdogReset() {
  __asm__ __volatile__ (
    "wdr\n"
  );
}

void watchdogConfig(uint8_t x) {
#ifdef WDCE //does it have a Watchdog Change Enable?
 #ifdef WDTCSR
  WDTCSR = _BV(WDCE) | _BV(WDE);
 #else
  WDTCR= _BV(WDCE) | _BV(WDE);
 #endif
#else //then it must be one of those newfangled ones that use CCP
  CCP=0xD8; //so write this magic number to CCP
#endif 

#ifdef WDTCSR
  WDTCSR = x;
#else
  WDTCR= x;
#endif
}


/*
 * void writebuffer(memtype, buffer, address, length)
 */
static inline void writebuffer(int8_t memtype, addr16_t mybuff,
             addr16_t address, pagelen_t len)
{
    switch (memtype) {
    case 'E': // EEPROM
#if SUPPORT_EEPROM || BIGBOOT
        while(len--) {
      eeprom_write_byte((address.bptr++), *(mybuff.bptr++));
        }
#else
  /*
   * On systems where EEPROM write is not supported, just busy-loop
   * until the WDT expires, which will eventually cause an error on
   * host system (which is what it should do.)
   */
  while (1)
      ; // Error: wait for WDT
#endif
  break;
    default:  // FLASH
  /*
   * Default to writing to Flash program memory.  By making this
   * the default rather than checking for the correct code, we save
   * space on chips that don't support any other memory types.
   */
  {
      // Copy buffer into programming buffer
      uint16_t addrPtr = address.word;

      /*
       * Start the page erase and wait for it to finish.  There
       * used to be code to do this while receiving the data over
       * the serial link, but the performance improvement was slight,
       * and we needed the space back.
       */
#ifdef FOURPAGEERASE
      if ((address.bytes[0] & ((SPM_PAGESIZE<<2)-1))==0) {
#endif
      __boot_page_erase_short(address.word);
      boot_spm_busy_wait();
#ifdef FOURPAGEERASE
      }
#endif

      /*
       * Copy data from the buffer into the flash write buffer.
       */
      do {
    __boot_page_fill_short((uint16_t)(void*)addrPtr, *(mybuff.wptr++));
    addrPtr += 2;
      } while (len -= 2);

      /*
       * Actually Write the buffer to flash (and wait for it to finish.)
       */
      __boot_page_write_short(address.word);
      boot_spm_busy_wait();
#if defined(RWWSRE)
      // Reenable read access to flash
      __boot_rww_enable_short();
#endif
  } // default block
  break;
    } // switch
}

static inline void read_mem(uint8_t memtype, addr16_t address, pagelen_t length)
{
    uint8_t ch;

    switch (memtype) {

#if SUPPORT_EEPROM || BIGBOOT
    case 'E': // EEPROM
  do {
      putch(eeprom_read_byte((address.bptr++)));
  } while (--length);
  break;
#endif
    default:
  do {
#ifdef VIRTUAL_BOOT_PARTITION
        // Undo vector patch in bottom page so verify passes
      if (address.word == rstVect0) ch = rstVect0_sav;
      else if (address.word == rstVect1) ch = rstVect1_sav;
      else if (address.word == saveVect0) ch = saveVect0_sav;
      else if (address.word == saveVect1) ch = saveVect1_sav;
      else ch = pgm_read_byte_near(address.bptr);
      address.bptr++;
#elif defined(RAMPZ)
      // Since RAMPZ should already be set, we need to use EPLM directly.
      // Also, we can use the autoincrement version of lpm to update "address"
      //      do putch(pgm_read_byte_near(address++));
      //      while (--length);
      // read a Flash and increment the address (may increment RAMPZ)
      __asm__ ("elpm %0,Z+\n" : "=r" (ch), "=z" (address.bptr): "1" (address));
#else
      // read a Flash byte and increment the address
      __asm__ ("lpm %0,Z+\n" : "=r" (ch), "=z" (address.bptr): "1" (address));
#endif
      putch(ch);
  } while (--length);
  break;
    } // switch
}


#if (APP_NOSPM == 0)

/*
 * Separate function for doing spm stuff
 * It's needed for application to do SPM, as SPM instruction works only
 * from bootloader.
 *
 * How it works:
 * - do SPM
 * - wait for SPM to complete
 * - if chip have RWW/NRWW sections it does additionaly:
 *   - if command is WRITE or ERASE, AND data=0 then reenable RWW section
 *
 * In short:
 * If you play erase-fill-write, just set data to 0 in ERASE and WRITE
 * If you are brave, you have your code just below bootloader in NRWW section
 *   you could do fill-erase-write sequence with data!=0 in ERASE and
 *   data=0 in WRITE
 */
static void do_spm(uint16_t address, uint8_t command, uint16_t data)  __attribute__ ((used));
static void do_spm(uint16_t address, uint8_t command, uint16_t data) {
    // Do spm stuff
    asm volatile (
  "    movw  r0, %3\n"
    "    __wr_spmcsr %0, %1\n"
    "    spm\n"
    "    clr  r1\n"
    :
    : "i" (_SFR_MEM_ADDR(__SPM_REG)),
        "r" ((uint8_t)command),
        "z" ((uint16_t)address),
        "r" ((uint16_t)data)
    : "r0"
    );

    // wait for spm to complete
    //   it doesn't have much sense for __BOOT_PAGE_FILL,
    //   but it doesn't hurt and saves some bytes on 'if'
    boot_spm_busy_wait();
#if defined(RWWSRE)
    // this 'if' condition should be: (command == __BOOT_PAGE_WRITE || command == __BOOT_PAGE_ERASE)...
    // but it's tweaked a little assuming that in every command we are interested in here, there
    // must be also SELFPRGEN set. If we skip checking this bit, we save here 4B
    if ((command & (_BV(PGWRT)|_BV(PGERS))) && (data == 0) ) {
      // Reenable read access to flash
      __boot_rww_enable_short();
    }
#endif
}
#endif



#if BIGBOOT
/*
 * Optiboot is designed to fit in 512 bytes, with a minimum feature set.
 * Some chips have a minimum bootloader size of 1024 bytes, and sometimes
 * it is desirable to add extra features even though 512bytes is exceedded.
 * In that case, the BIGBOOT can be used.
 * Our extra features so far don't come close to filling 1k, so we can
 * add extra "frivolous" data to the image.   In particular, we can add
 * information about how Optiboot was built (which options were selected,
 * what version, all in human-readable form (and extractable from the
 * binary with avr-strings.)
 * 
 * This can always be removed or trimmed if more actual program space
 * is needed in the future.  Currently the data occupies about 160 bytes,
 */
#define xstr(s) str(s)
#define str(s) #s
#define OPTFLASHSECT __attribute__((section(".fini8")))
#define OPT2FLASH(o) OPTFLASHSECT const char f##o[] = #o "=" xstr(o)


#if LED_START_FLASHES
OPT2FLASH(LED_START_FLASHES);
#endif
#if LED_DATA_FLASH
OPT2FLASH(LED_DATA_FLASH);
#endif
#if LED_START_ON
OPT2FLASH(LED_START_ON);
#endif
#ifdef LED_NAME
OPTFLASHSECT const char f_LED[] = "LED=" LED_NAME;
#endif

#if SUPPORT_EEPROM
OPT2FLASH(SUPPORT_EEPROM);
#endif
#if BAUD_RATE
OPT2FLASH(BAUD_RATE);
#endif
#if SOFT_UART
OPT2FLASH(SOFT_UART);
#endif
#if defined(UART)
OPT2FLASH(UART);
#endif

OPTFLASHSECT const char f_date[] = "Built:" __DATE__ ":" __TIME__;
#if BIGBOOT
OPT2FLASH(BIGBOOT);
#endif
#ifdef VIRTUAL_BOOT_PARTITION
OPTFLASHSECT const char f_boot[] = "Virtual_Boot_Partition";
#endif
OPT2FLASH(F_CPU);
OPTFLASHSECT const char f_device[] = "Device=" xstr(__AVR_DEVICE_NAME__);
#ifdef OPTIBOOT_CUSTOMVER
OPT2FLASH(OPTIBOOT_CUSTOMVER);
#endif
OPTFLASHSECT const char f_version[] = "Version=" xstr(OPTIBOOT_MAJVER) "." xstr(OPTIBOOT_MINVER);

#endif

ну и в каждый скетч добавлять это, чтобы работал процесс прошивки без сигнала DTR (скорость ставим ту, на которую настраивали загрузчик): 

#include <avr/wdt.h>
void setup() 
{
Serial.begin (57600);
}

void loop() 
{
 if (Serial.available()&&Serial.read()==0x30){eeprom_write_byte((uint8_t*)254, 0); wdt_enable(WDTO_15MS);}
}

Через переход на адрес памяти загрузчика (как в посте #11) у меня не получилось реализовать. Сделал через вотчдог. Смысл такой - при получении команды на прошивку от IDE, ардуина пишет 0 в еепром в ячейку 254 , в бутлодыре читается эта ячейка, если 0, то подменяем показания MCUSR, как будто был вшений сброс от ноги reset. и пишем обратно ячейку в 0xFF. и далее лодырь действует по стандартной схеме, как будто дернули ресет. 

долго бился. Основное что не получалось, как только что-нибудь добавлял в файл optiboot.c сразу ругался компилятор типа размер загрузчика превышен, пробовал такую команду BIGBOOT=1 (при этом размер по идее удваивается), все в этом случае компилировалось, но нихрена не работало. Единственным получившимся решением стало у меня убирание мигания 3 раза встроенным LED, часть кода освободилось и мои строчки влезли, поэтому я компилировал такой строкой  omake atmega328 LED_START_FLASHES=0 BAUD_RATE=57600.   В общем основная цель то у меня была по RS485 прошивать, следующий этап , тот оптибут мучить, который поддерживает rs485. продолжение следует короче

Ну, блин!  RS485 какое имеет отношение к теме "Беспроводная заливка скетча"?

Ну проблема то такая же была на пути. Ок дальше не пишу про rs485.

Проблема одна и та же - нет DTR.

Вот тут есть кое что по вашей теме.

Почему проблема? Для радиоканала с JDY-40 способ из #10 работает.

Тема интересная. У Дмитрия Осипова на канале Youtube есть вариант попроще - несколько обучающих видеоуроков на данную тему (ссылки на ресурсы ниже).

https://www.youtube.com/watch?v=wOyRgg8vE6I

https://www.youtube.com/watch?v=UW46NwTVDUo

Попробовал на своей конструкции робота ради интереса - 5 метров без преград, 12 Кб скетч. Но hc-05 дороже, хотелось бы на jdy-31. Как в них менять скорость - использовать АТ команды не нашёл. Может вы знаете? 

На HC-05 заливка давно известна, пробовал лет 5 назад. К сожалению с JDY-31 не имел дела, даже не знал, что такие есть.

Модуль такой купил, пробовал в разных поделках, пока на ТХ не подал 5 В ). Сейчас, в продолжение темы, хотел повесить на один  JDY-31 несколько про мини и управлять-заливать параллельно, но установка скорости притормозила желания.

Jaeger, а вы пробовали по методу #10 , заливать просто через USB_TTL без сигнала DTR? у меня почему то не  работает. Я пробовал даже переход к определённому месту памяти загрузчика (листинг в файле  optiboot_atmega328.lst) все равно никак. Рестарт идет, таймаут тоже, но скетч не льётся. Причём к разным местам памяти пробовал . Эх ну не хватает мне скилла и все тут. 

Просто мой рабочий метод с еепром ну никак не влезает в оптибут RS485 (превышение размера загрузчика).  Может чтение еепром в виде ассемблерных вставок сделать , чтоб влезло? кто знает подскажите как это будет выглядеть

if (!eeprom_read_byte((uint8_t*)254))
    7e06:	8e ef       	ldi	r24, 0xFE	; 254
    7e08:	90 e0       	ldi	r25, 0x00	; 0
    7e0a:	e1 d0       	rcall	.+450    	; 0x7fce <eeprom_read_byte>
    7e0c:	81 11       	cpse	r24, r1
    7e0e:	08 c0       	rjmp	.+16     	; 0x7e20 <main+0x1c>
{
eeprom_write_byte((uint8_t*)254, 0xFF);
    7e10:	6f ef       	ldi	r22, 0xFF	; 255
    7e12:	8e ef       	ldi	r24, 0xFE	; 254
    7e14:	90 e0       	ldi	r25, 0x00	; 0
    7e16:	e3 d0       	rcall	.+454    	; 0x7fde <eeprom_write_byte>
MCUSR = ~(_BV(WDRF));
    7e18:	87 ef       	ldi	r24, 0xF7	; 247
    7e1a:	84 bf       	out	0x34, r24	; 52
ch=2;
    7e1c:	82 e0       	ldi	r24, 0x02	; 2
    7e1e:	03 c0       	rjmp	.+6      	; 0x7e26 <main+0x22>
}
else ch = MCUSR;
    7e20:	84 b7       	in	r24, 0x34	; 52

Вам принципиально нужно уместить загрузчик в 512 байт? Он может быть  1кБ или 2кБ. Заливку по проводам без DTR попробую.

нет не принципиально. Я не знаю как увеличить размер загрузчика. Командой BIGBOOT=1 ? так у меня не работает. А в обычном варианте компилятор не дает собрать бутлоадер более 512. 

Загрузка по проводу без DTR с переходом на адрес загрузчика работает (#10). Повторяю, что у меня оптибут из исходников по ссылке из поста #1. Этот загрузчик поддерживает EEPROM и соответственно "длинный" оптибут, но не поддерживает RS485. Загрузчик от https://github.com/SodaqMoja/optiboot наоборот не поддерживает EEPROM. Вероятно Вам нужно как-то соединить их. При длинном загрузчике нужно установить еще соотв-е фьюзы. 

А вот почему не работало на длинном загрузчике, пасиб!про фьюзы погуглю как их поправить . Ну и потестю ещё почему переход по адресу не срабатывает.

Посмотрел калькулятор фьюзов. Действительно там настраивается размер секции загрузчика и начальный адрес указан. А вы меняли фьюзы в файле boards, когда оптибут использовали с примером #10? Ведь если не меняли, тогда у вас переход по адресу 0х3800 правильный (как для старого загрузчика 2кб) и это объясняет почему у меня не работало, я то правил фьюзы от уны, а там тож оптибут. Мне нужен адрес 0x3F00 (256words что есть 512bytes) Домой приеду проверю эту теорию.

Спасибо за наводку! Все заработало на оптибут RS485 по моей схеме с еепром (см #21).  Чтобы заработал увеличенный загрузчик 1кб (командой BIGBOOT=1 при компиляции в командной строке), нужно естественно было ещё поправить фьюз HIGH в файле boards.txt на значение DC вместо DE  (в моём случае) . 

По вашей схеме с переходом по адресу так и не заработало, почему - загадка. 

и кстати это я неправильный вывод сделал: 

это адрес начала самого большего из возможных загрузчика вообще в 4кб. а у вас 512b   Т.е. если вы скетч большой загрузите, то по адресу 0x3800 вообще , я так понимаю, уже основной скетч будет находится . Так что применяйте правильный адрес 

Мой лодырь укладывается в 512 байт, поэтому его стартовый адрес 0х3F00. Этот адрес я и указываю в приложении. В boards  я указываю только скорость заливки по uart, остальное меня не волнует, поскольку лодырь и фьюзы к нему я заливаю через сторонний гуй (GUI AVRDUDESS). 

понятно, ну тогда поправьте #10 , а то меня ввело в заблуждение 0x3800

капец, я нашел приничу, все было в том что,  я не точно ваш скетч использовал и написал ждать символа STK_GET_SYNC (0x30), а у вас ждёт STK_CRC_EOP (0x20) и из-за этого и не работало!!! теперь мои танцы с еепром как бы и не актуальны получается. И кстати даже без MCUSR = (_BV(EXTRF)) перед переходом на загрузчик тоже работает (все таки я думаю что в этом регистре можно только сбрасывать биты - это же тоже write, что и указано в шитодате).  Все встало на свои места. 

Оно и с адресом 0х3800 стартует, поскольку до адреса загрузчика все пока пусто. Я тоже так думал, что запись 1 в MCUSR только аппаратно, но практика показывает что при MCUSR = (_BV(EXTRF)) приложение запускается, а при MCUSR = 0 загрузчик сидит в каком-то лупе и приложение не стартует, хотя загрузку может производить. И еще, без MCUSR = (_BV(EXTRF)) после передергивания питания загрузчик не грузит приложение, только после кнопочного ресета. Блин, "сам в шоке!"

Дак может MCUSR вообще не трогать перед переходом. Т.е не надо ни =0, ни установки EXTRF

Судя по 

MCUSR = (_BV(EXTRF));//MCUSR = 0;
Serial.print((MCUSR),HEX);

все-таки пишет в этот регистр.

Хм, странно, я так пробовал, было ноль. Ладно, хорошо если так

У меня алгоритм такой, что перед обновлением прошивки на МК поступает соответствующая команда. И только после этого ардуина ждёт CRC_EOP. При этом в эфире естественно делается тихое окно .

MCUSR = (_BV(EXTRF));//MCUSR = 0;
Serial.print((MCUSR),HEX);

а вы попробуйте распечатать MCUSR до записи единицы и поймете, что она там уже была. Последние версии оптибут вроде не сбрасывают MCUSR. (ну кроме бита WDRF, его сбрасывает лодырь) 

Вы правы, я лажанулся! -(

Выходит что ни мой способ с еепром ни ваш с переходом по адресу нормально не работает, если хотя бы раз после включения питания не был произведён внешний ресет по пину reset

Да, совершенно верно. Хочу попробовать еще аппаратный способ (не трогая загрузчик) - уменьшить таймаут при включении пердохранителями (фьюзами) и замкнуть DTR на массу. Типа сначала сработает ресет по включению, потом внешний ресет. Если наоборот то ресет при включении стирает все биты (кроме своего) в MCUSR.