Tooltron

#include "bootloader.h"

// Setup the default fuses

FUSES = {

    .low = (FUSE_SUT0 & FUSE_CKSEL3 & FUSE_CKSEL2 & FUSE_CKSEL0),

    .high = (FUSE_EESAVE & FUSE_SPIEN),

    .extended = (FUSE_SELFPRGEN),

};

// Error thresholds

#define MAX_RETRIES 5       // Number of times to retry before giving up

//Status LED

#define LED_DDR  DDRB

#define LED_PORT PORTB

#define LED      PORTB1

/**

 * Where we store the jump to user code. The jump address is in words

 * due to how the rjmp instruction works. It is 1 word below the bootloader

 */

void (*main_start)(void) = BOOT_START/2 - 1;

/**

 * We declare main as naked so that there is no overhead for entering

 * and returning from this function since we don't really care about

 * what happens to it after we leave it

 */

int main(void) __attribute__ ((naked));

typedef union {

    uint8_t bytes[2];

    int16_t sword;

} rjump_t;

/** 

 * Restore the reset vector to point to the end of ctors. This

 * is because we are stripping out the interrupt vector table

 * from the bootloader as we don't use it.

 */

void ResetVector (void) __attribute__((naked))

                        __attribute__((section(".reset")));

void ResetVector(void) {

    asm("rjmp __ctors_end");

}

// SPM_PAGESIZE is set to 32 bytes

void onboard_program_write(uint16_t page, uint8_t *buf) {

  uint16_t i;

  boot_page_erase (page);

  boot_spm_busy_wait ();      // Wait until the memory is erased.

  for (i=0; i < SPM_PAGESIZE; i+=2){

    // Set up little-endian word.

    boot_page_fill (page + i, buf[i] | (buf[i+1] <<8));

  }

  boot_page_write (page);     // Store buffer in flash page.

  boot_spm_busy_wait();       // Wait until the memory is written.

}

int main(void) {

  uint8_t mbuf[PROGD_PACKET_SIZE];

  rjump_t jbuf;

  uint16_t caddr = MAIN_ADDR;

  uint8_t iteration;

  uint8_t resp;

  uint16_t prog_len;

  uint8_t i;

  uint8_t retries;

retry_jpnt:

  iteration = 0;

  retries = 0;

  // Clear the watchdog timer

  MCUSR &= ~_BV(WDRF);

  wdt_disable();

  WDTCSR = 0;

  rs485_init(51); //MAGIC NUMBER??

  //set LED pin as output

  LED_DDR |= 0x07;

  PORTB = 0x07;

  //Start bootloading process

  send_packet(TT_BOOT);

  resp = parse_packet(mbuf);

  // Enter programming mode 

  if (resp == TT_PROGM) {

    prog_len = mbuf[0];

    prog_len |= mbuf[1] << 8;

    // This will insert a NOP into the user code jump in case

    // the programming fails

    for (i = 0; i < PROGD_PACKET_SIZE; i++) {

      mbuf[i]= 0;

    }

    onboard_program_write(BOOT_START - SPM_PAGESIZE, mbuf);

  // Run user code

  } else {

      main_start();

  }

  send_packet(TT_ACK);

  while(1) {

      resp = parse_packet(mbuf);

      if (resp == TT_PROGD) {

          // We need to muck with the reset vector jump in the first page

          if (iteration == 0) {

              // Store the jump to user code

              jbuf.bytes[0] = mbuf[0];

              jbuf.bytes[1] = mbuf[1];

              // Rewrite the user code jump to be correct since we are

              // using relative jumps (rjmp)

              jbuf.sword &= 0x0FFF;

              jbuf.sword -= (BOOT_START >> 1) - 1;

              jbuf.sword &= 0x0FFF;

              jbuf.sword |= 0xC000;

              // Rewrite the reset vector to jump to the bootloader

              mbuf[0] = (BOOT_START/2 - 1) & 0xFF;

              mbuf[1] = 0xC0 | (((BOOT_START/2 - 1) >> 8) & 0x0F);

              iteration = 1;

          }

          // Write the page to the flash

          onboard_program_write(caddr, mbuf);

          caddr += PROGD_PACKET_SIZE;

          retries = 0;

      } else {

          send_packet(TT_NACK);

          retries++;

          // If we failed too many times, reset. This goes to the start

          // of the bootloader function

          if (retries > MAX_RETRIES) {

              goto retry_jpnt;

          }

      }

      send_packet(TT_ACK);

      // Once we write the last packet we must override the jump to

      // user code to point to the correct address

      if (prog_len <= PROGD_PACKET_SIZE) {

          for (i = 0; i < PROGD_PACKET_SIZE; i++) {

              mbuf[i]= 0;

          }

          mbuf[PROGD_PACKET_SIZE-2] = jbuf.bytes[0];

          mbuf[PROGD_PACKET_SIZE-1] = jbuf.bytes[1];

          onboard_program_write(BOOT_START - SPM_PAGESIZE, mbuf);

          main_start();

      } else { 

          prog_len -= PROGD_PACKET_SIZE;

      }

  }

  // Should never get here

  return -1;

}