Which microcontroller to choose:
Microcontroller ATMega128: Offers 128 KByte Flash (programming memory) and 4 KByte RAM a lot of space for your own programs and for the storage of graphics elements
Microcontroller ATMega2561: Almost identical to the ATMega128 but comes with doubled Flash memory (program memory) and doubled RAM. This controller is the better choose if you need to store a lot of graphical images (e.g. logos, photos, buttons etc.) or if you need to keep a lot of data in RAM (for calculating, buffering etc).
Microcontroller AT90CAN128: Almost identical to the ATMega128, but comes with an additional internal CAN module. Remark: For a connection to a CAN bus you need a separate CAN tranceiver. For our modules D071 and D072 the tranceiver together with the needed CAN bus termination resistor will be soldered on the module by us if you order a AT90CAN128.
General comments for the needed memory: A programming memory of 128 KByte is a lot and usually enough for most programs. Graphical data needs a lot of additional space. E.g. a 65K color graphics needs at a resolution of 176x132 pixel approx. 45 KByte of your programming space. Even with our included tools for color reduction and compressing and decompressing the graphics can easily eat up 15 KByte. If you need a lot of those your might come into trouble. Then a ATMega2561 is the better solution and is recommended by us. The doubled flash and doubled RAM is available for a relatively small additional price.