Using the ATmega2560V-8au with Arduino

Hi,

I am having trouble with this chip and using the Arduino IDE. I am uploading the bootloader hex file for the mega2560 to the board and settting the fuses and lock bits fine and I can then upload my sketch via arduino itself but the bootloader is then trashed and I am unable to repeat the upload and am forced to reset the chip in Studio.

Fuse settings :

LOW 0xFF

HIGH 0xD8

EXT 0xFE

LOCK BIT 0xCF

Boards.txt entry

mega2560V.name=Arduino Mega 2560 or Mega ADK (8MHz Internal, Baud=57.6K)

mega2560V.upload.protocol=wiring

mega2560V.upload.maximum_size=258048

mega2560V.upload.speed=57600

mega2560V.bootloader.low_fuses=0xFF

mega2560V.bootloader.high_fuses=0xD8

mega2560V.bootloader.extended_fuses=0xFE

mega2560V.bootloader.path=stk500v2

mega2560V.bootloader.file=stk500boot_v2_mega2560.hex

mega2560V.bootloader.unlock_bits=0x3F

mega2560V.bootloader.lock_bits=0x0F

mega2560V.build.mcu=atmega2560

mega2560V.build.f_cpu=8000000L

mega2560V.build.core=arduino:arduino

mega2560V.build.variant=arduino:mega

Does anyone know of any obvious consideration I may have not thought of. The 2560 and the 2560V are as far as I can tell more or less identical inside (they have the same datasheet) so except for voltage and speed being the main difference I can't think of anything else.

Any help or suggestions appreciated.

Why did you change the upload speed and the extended fuse byte (changes brown out level), and the lock bits? Standard boards.txt entry - if using an external crystal, I would have thought that only the build.f_cpu = 8000000L would have changed.

mega2560.name=Arduino Mega 2560 or Mega ADK

mega2560.upload.protocol=wiring

mega2560.upload.maximum_size=258048

mega2560.upload.speed=115200

mega2560.bootloader.low_fuses=0xFF

mega2560.bootloader.high_fuses=0xD8

mega2560.bootloader.extended_fuses=0xFD

mega2560.bootloader.path=stk500v2

mega2560.bootloader.file=stk500boot_v2_mega2560.hex

mega2560.bootloader.unlock_bits=0x3F

mega2560.bootloader.lock_bits=0x0F

mega2560.build.mcu=atmega2560

mega2560.build.f_cpu=16000000L

mega2560.build.core=arduino

mega2560.build.variant=mega

There was an old forum thread from a couple of years ago where someone posted a boards entry to help someone using this chip and from what I gathered, it worked fine for them. I changed the extended byte to lower the brown out to 1.8Vto see how the board would run (battery powered application). Probably going to set it back to default though. I have been tweaking a few things in the programmers.txt and discovered a few things. The FTDI chip Im using wasn't actually connected to the board ground, only to the USB ground so I had no common ground... ooops. After correcting this, I failed to return programmers.txt to it's original state which I think may have been part of the problem. I had changed the 'protocol' to 'stk500v2' whereas the default is 'wiring'. The IDE is now uploading without trashing the bootloader though I think there may be a bug lurking somewhere as I have had it timeout a couple of times still. Im only powering the FTDI chip off of the USB and using it's internal 3v3 reg to power the IO to the MCU. I have feeling that connecting the USB without powering the board up might be 'upsetting something'.

:D