ARDUINO MEGA Update Bootloader

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Note: This document only applies to the MEGA 2560 and MEGA ADK Arduino Boards. All other Arduino boards bootloaders are good!

Arduino 2560 Bootloader Issue

The current bootloader burned onto the Arduino MEGA 2560/ADK is not compatible with ROBOTC. In its current form, you will be able to download the ROBOTC Firmware to the Arduino MEGA 2560/ADK, but you will not able to download any user programs.

The reason for this is because there is a bug in the Arduino MEGA 2560/ADK firmware that does not allow flash write commands to start at anywhere but the beginning of flash memory (0x000000). See the bottom of this page for more technical details.

Because ROBOTC is not able to burn a new bootloader as of today, you will need to use the Arduino's Open Source language with our a modified bootloader file to re-burn your bootloader on your Arduino MEGA 2560/ADK boards. Once the new bootloader is burned, you will be able to program your Arduino MEGA 2560/ADK with both ROBOTC and the Arduino Open Source language.

Equipment Needed

To burn the bootloader, you'll need to buy an AVR-ISP (in-system programmer), USBtinyISP or build a ParallelProgrammer. The programmer should be connected to the ICSP pins (the 2 by 3 pin header) - make sure you plug it in the right way. The board must be powered by an external power supply or the USB port.

Software Needed

ROBOTC is not currently able to burn a bootloader onto an Arduino board, so you'll need to download a copy of the latest versio

Technical Details

ROBOTC's Fix:

case CMD_LOAD_ADDRESS:
 #if defined(RAMPZ)
  address = (((address_t)(msgBuffer[1])<<24)|((address_t)(msgBuffer[2])<<16)|
            ((address_t)(msgBuffer[3])<<8)|msgBuffer[4]))<<1;
 #else
  address = (((msgBuffer[3])<<8)|(msgBuffer[4]))<<1;  //convert word to byte address
 #endif
 msgLength = 2;
 msgBuffer[1] =	STATUS_CMD_OK;
 break;
 
case CMD_PROGRAM_FLASH_ISP:
case CMD_PROGRAM_EEPROM_ISP:
{
  unsigned int	size	=	((msgBuffer[1])<<8) | msgBuffer[2];
  unsigned char	*p	=	msgBuffer+10;
  unsigned int	data;
  unsigned char	highByte, lowByte;
  address_t		tempaddress	=	address;
 
 
  if ( msgBuffer[0] == CMD_PROGRAM_FLASH_ISP )
  {
    // erase only main section (bootloader protection)
    if (eraseAddress < APP_END )
    {
      boot_page_erase(eraseAddress);	// Perform page erase
      boot_spm_busy_wait();		// Wait until the memory is erased.
      eraseAddress += SPM_PAGESIZE;	// point to next page to be erase
    }
case CMD_PROGRAM_FLASH_ISP:
case CMD_PROGRAM_EEPROM_ISP:
{
  unsigned int	size	=	((msgBuffer[1])<<8) | msgBuffer[2];
  unsigned char	*p	=	msgBuffer+10;
  unsigned int	data;
  unsigned char	highByte, lowByte;
  address_t		tempaddress	=	address;
 
 
  if ( msgBuffer[0] == CMD_PROGRAM_FLASH_ISP )
  {
    eraseAddress = address & 0xFFFFFF00;   // ROBOTC Custom Bootloader Addition
 
    // erase only main section (bootloader protection)
    if (eraseAddress < APP_END )
    {
      boot_page_erase(eraseAddress);	// Perform page erase
      boot_spm_busy_wait();		// Wait until the memory is erased.
      eraseAddress += SPM_PAGESIZE;	// point to next page to be erase
    }