External EEPROM Use For Burn Arduino

Projects General Guidance
7

I updated Nick's file to provide some options for what to do with the boot fuses, mostly the 2nd half of this, but I copied the whole function where the fuse is written. Maybe the original program can be similarly tweaked.
The variable BOOTABLE is created by reading a button press after startup.

// returns true if error, false if OK
bool updateFuses (const bool writeIt)
{
  Serial.println F(("updateFuses"));
  unsigned long addr;
  unsigned int  len;

  byte fusenumber = currentSignature.fuseWithBootloaderSize;

  // if no fuse, can't change it
  if (fusenumber == NO_FUSE)
  {
    //    ShowMessage (MSG_NO_BOOTLOADER_FUSE);   // maybe this doesn't matter?
    return false;  // ok return
  }

  addr = currentSignature.flashSize;
  len = currentSignature.baseBootSize;

  if (lowestAddress == 0)
  {
    Serial.print F(("lowestAddress = 0,  fuse = "));
    fuses [fusenumber] |= 1; // don't use bootloader
    Serial.println (fuses [fusenumber], HEX);
  }
  else
  {
    byte newval = 0xFF;

    if (lowestAddress == (addr - len))
      newval = 3;
    else if (lowestAddress == (addr - len * 2))
      newval = 2;
    else if (lowestAddress == (addr - len * 4))
      newval = 1;
    else if (lowestAddress == (addr - len * 8))
      newval = 0;
    else
    {
      ShowMessage (MSG_BAD_START_ADDRESS);
      return true;
    }
    Serial.print F(("newval "));
    Serial.println (newval, HEX);
    if (newval != 0xFF)
    {
      {
        newval <<= 1;  //
        fuses [fusenumber] &= ~0x07;
        fuses [fusenumber] |= newval;
        Serial.print F(("newval "));
        Serial.println (newval, HEX);
      }  // if valid

    }  // if not address 0
  }

  if (writeIt)
  {
    Serial.println F(("writeIt"));
    writeFuse (fuses [fusenumber], fuseCommands [fusenumber]);
    // variation to set fuses based on BOOTABLE
    // = 1 is bootloader not run (set LSB to 1), = 0 is bootloader run (clear LSB to 0)
    //TLZ - 09/13/16 - force new values into fuses for ATMEGA2560
    // Modified 1/29 for boot/no boot
    if (strcmp (currentSignature.desc, "ATmega2560") == 0)
    {
      if (BOOTABLE == 1) {
        Serial.println F(("2560 no bootloader in writeIt"));
        writeFuse (0xFF, writeLowFuseByte); //
        writeFuse (0xD9, writeHighFuseByte); // low bit set
        writeFuse (0xFD, writeExtendedFuseByte); //
      }
      else { // BOOTABLE = 0
        Serial.println F(("2560 bootloader in writeIt"));
        writeFuse (0xFF, writeLowFuseByte); //
        writeFuse (0xD8, writeHighFuseByte); // low bit clear
        writeFuse (0xFD, writeExtendedFuseByte); //
      }
    }

    if (strcmp (currentSignature.desc, "ATmega328P") == 0)
    {
      if (BOOTABLE == 1) {
        Serial.println F(("328P no bootloaderin writeIt"));
        writeFuse (0xFF, writeLowFuseByte);
        writeFuse (0xDF, writeHighFuseByte); // low bit set
        writeFuse (0xFD, writeExtendedFuseByte);
      }
      else { // BOOTLOADER = 0
        Serial.println F(("328P  bootloader in writeIt"));
        writeFuse (0xFF, writeLowFuseByte);
        writeFuse (0xDE, writeHighFuseByte); // low bit clear
        writeFuse (0xFD, writeExtendedFuseByte);
      }
    }

    if (strcmp (currentSignature.desc, "ATmega1284P") == 0)
    {
      if (BOOTABLE == 1) {
        Serial.println F(("1284P bootloader in writeIt"));
        writeFuse (0xF7, writeLowFuseByte);
        writeFuse (0xDF, writeHighFuseByte); // low bit set
        writeFuse (0xFD, writeExtendedFuseByte);
      }
      else {
        Serial.println F(("1284P no bootloader in writeIt"));
        writeFuse (0xF7, writeLowFuseByte);
        writeFuse (0xDE, writeHighFuseByte); // low bit clear
        writeFuse (0xFD, writeExtendedFuseByte);
      }
    }
  }

  return false;
}  // end of updateFuses