Arduino programming fails on ATmega2560

[Luke Weston]

I have a new board here with an ATmega2560 and an ATmega8U2... identical, for all practical intents and purposes, as far as the microcontrollers are concerned, to an Arduino Mega 2560.

I have googled around and found the appropriate hex files for both microcontrollers and programmed them both.

Both 16 MHz crystal oscillators are confirmed to be running.

The ATmega8U2 USB virtual serial port appears in the OS when plugged in.

Pin 13 on the ATmega2560 flashes two times in fast succession with a longer pause between the double flashes, which I assume is the default pin 13 "test" output from that particular bootloader.

But programming the board via the Arduino environment doesn't work. It generates one brief blink on the RXD LED and then just sits there repeating the timeout error.

Binary sketch size: 1,632 bytes (of a 258,048 byte maximum)

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: stk500v2_ReceiveMessage(): timeout

This is just with your basic blink sketch, for the sake of example.

If you google this error, lots of people across various forums etc. seem to report that this is a problem, but nobody has any clear answer about what causes it or fixes it.

After programming both the same hex files onto the ATmega2560 and the ATmega8U2 on an Ethermega, the default digital test waveform on pin 13 is exactly the same, (two high pulses with a short low time between them, and a longer gap between each pair of pulses) which is what you'd expect, and programming the board in the normal way via the virtual UART via the Arduino environment works perfectly fine.

If I cut the UART lines on the board between the ATmega8U2 and the ATmega2560 and tie them together on the ATmega8U2 side, and test serial loopback through a serial terminal, then this successfully works, and it lights up both the ATmega8U2's TXD and RXD LEDs, which is what you'd expect.

Anyone have any idea how to fix it?

Cheers,

  Luke

[David Lyon]

don't know.

But it sounds like the bootloader might be missing.

Maybe you could try ICSP.

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[chris bate]

which version of the arduino environment are you running? and what operating system?

[Luke Weston]

In case you're wondering, there's nothing wrong with the hardware or the development environment... the answer is that you've got to set all the fuse bits correctly when programming the firmware into the ATmega8U2... nothing wrong with the firmware on the ATmega2560.

Desoldering that ATmega8U2 for no reason was certainly a pain in the arse.

Cheers,
  Luke