bootloader.c

#include "bootloader.h"
#include "dev/watchdog.h"
#include <util/delay.h>
#include <avr/wdt.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include "dev/usb/usb_drv.h"

volatile uint32_t Boot_Key ATTR_NO_INIT;

bool
bootloader_is_present(void) {
        return pgm_read_word_far(BOOTLOADER_START_ADDRESS)!=0xFFFF;
}

void
Jump_To_Bootloader(void)
{
        uint8_t i;
        
#ifdef UDCON
        // If USB is used, detach from the bus
        Usb_detach();
#endif

        // Disable all interrupts
        cli();

        // Set the bootloader key to the magic value and force a reset
        Boot_Key = MAGIC_BOOT_KEY;

        // Wait two seconds for the USB detachment to register on the host
        for (i = 0; i < 128; i++)
                _delay_ms(16);

        // Set the bootloader key to the magic value and force a reset
        Boot_Key = MAGIC_BOOT_KEY;
        
        watchdog_reboot();
}

extern void Bootloader_Jump_Check(void) ATTR_INIT_SECTION(3);

void
Bootloader_Jump_Check(void)
{
        // If the reset source was the bootloader and the key is correct, clear it and jump to the bootloader
        if(MCUSR & (1<<WDRF)) {
                MCUSR = 0;
                if(Boot_Key == MAGIC_BOOT_KEY) {
                        Boot_Key = 0;
                        wdt_disable();
                        
                        ((void (*)(void))BOOTLOADER_START_ADDRESS)();
                } else {
                        Boot_Key++;
                }
        } else {
                Boot_Key = MAGIC_BOOT_KEY-4;
        }
}