From ATMega328 to ATMega2560

Using Arduino Project Guidance
1

Hi Everyone,
I made this first board with the ATMega328. The idea was to make it work like an arduino, so I placed a ICSP por to burn the bootloader and an FTDI for the programing with a FTDI connector (https://www.sparkfun.com/products/9716?). It worked, I "told" the arduino software that the board was a Duemilanove before burning the bootloader and then I was ready to program via FTDI. Here the basic connections:

Now, I want to do the same thing but this time using the ATMega2560. So basically I connected the ICSP and the FTDI to the equivalent ports in the AT2560 as shown in the following schematic:

My concern is if this is going to work as it did with the AT328. Specifically:

  • If I tell the arduino software that the board is a Arduino Mega 2560 before burning the bootloader (like I did with the previous model), will I be able to use the FTDI port? since the Arduino Mega 2560 board does not have a FTDI itself. Instead it uses the ATMega16U for the USB interface.

Thanks in advance!

2

The FTDI and 16U are both acting as USB to TTL Serial adapters. They both show up to tha IDE software as serial ports. As long as you select the correct "serial port" the ATmega2560 should work just like an Arduino Mega 2560.

3

johnwasser:
The FTDI and 16U are both acting as USB to TTL Serial adapters. They both show up to tha IDE software as serial ports. As long as you select the correct "serial port" the ATmega2560 should work just like an Arduino Mega 2560.

I apologize for this late, late reply. I just wanted to say thanks. The board works as an Arduino Mega. There were a few steps I had to go through in order to make it work.

  • I was not able to use "Arduino as ISP" in order to write the bootloader to it. I found out that since the size of the memory on the 2560 was bigger than the ATMega328, ATMega168 (or similar) it needed a ISP version 2 cable to do so. I bought a new ICSP AVR programmer cable. (http://www.pololu.com/catalog/product/1300)

  • That was not enough. I had to add the option of using the version 2 "software" to the arduino software (inside TOOLS>PROGRAMMER). I did this:
    ##Add this to the bottom of the programmers.txt file.

avrispv2.name=AVR ISP v2
avrispv2.communication=serial
avrispv2.protocol=avrispv2

(instructions taken from Arduino Forum)

  • Then restart Arduino software and the option is there

Thanks again!

4

Can you possible post your schematic? I am trying to get an Atmega2560 with FTDI working myself and would appreciate some guidance! Thanks!

5

You can look at the Nano schematic (or the older Duemilanove) on the Products page and wire up the serial interface to the FTDI chip the same way. Just 3 signals - Rx, Tx, and DTR thru a 0.1uF cap to the Reset pin connect to the Atmega - plus power & Gnd.
CTS (clear to send) input on the FTDI should be connected to Gnd also, not sure if the driver looks at it or not. I always connect it just in case.