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/* Copyright 2021 QMK
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "bootloader.h"
#include <avr/wdt.h>
#include <util/delay.h>
#define FLASH_SIZE (FLASHEND + 1L)
/** \brief Entering the Bootloader via Software
*
* http://www.fourwalledcubicle.com/files/LUFA/Doc/120730/html/_page__software_bootloader_start.html
*/
#define BOOTLOADER_RESET_KEY 0xB007B007
uint32_t reset_key __attribute__((section(".noinit,\"aw\",@nobits;")));
__attribute__((weak)) void bootloader_jump(void) {
UDCON = 1;
USBCON = (1 << FRZCLK); // disable USB
UCSR1B = 0;
_delay_ms(5); // 5 seems to work fine
reset_key = BOOTLOADER_RESET_KEY;
// watchdog reset
wdt_enable(WDTO_250MS);
for (;;)
;
}
__attribute__((weak)) void mcu_reset(void) {
// watchdog reset
wdt_enable(WDTO_250MS);
for (;;)
;
}
/* this runs before main() */
void bootloader_jump_after_watchdog_reset(void) __attribute__((used, naked, section(".init3")));
void bootloader_jump_after_watchdog_reset(void) {
if ((MCUSR & (1 << WDRF)) && reset_key == BOOTLOADER_RESET_KEY) {
reset_key = 0;
((void (*)(void))((FLASH_SIZE - BOOTLOADER_SIZE) >> 1))();
}
}
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