Wise Clock 4 with ATmega1284

I thought that replacing the ATmega644P with its bigger brother ATmega1284P in Wise Clock 4 would be trivial. How wrong I was.

The first step was to burn the bootloader. After a bit of research, here is what I found out:

• USBtinyISP from adafruit cannot program chips with more than 64K of flash (see this thread);
• if you don't want to start from scratch (that is, compile the source code and figuring the fuses) there are at least 3 sources: ryanmsutton, maniacbug and calunium;
• USBtinyISP half-works: it writes to the flash, but reading back for verification purpose fails because of a bug in the firmware; I ignored the verification error;
• although burning the bootloader (any of the three mentioned above) seemed successful, uploading any sketch afterwards always failed;
• the setup from ryanmsutton did not work for me (I guess the fuses are wrong; then the core files also point to the arduino folder, instead of the sanguino, as it should be);
• with the bootloader from calunium (atmega1284p_16MHz.hex) I was able to upload sketches; these are the settings in boards.txt I used:

atmega1284.name=Sanguino W/ ATmega1284p 16mhz
atmega1284.upload.protocol=stk500v1
atmega1284.upload.maximum_size=129024
atmega1284.upload.speed=57600
atmega1284.bootloader.low_fuses=0xFF
atmega1284.bootloader.high_fuses=0x98
atmega1284.bootloader.extended_fuses=0xFD
atmega1284.bootloader.path=atmega
atmega1284.bootloader.file=atmega1284p_16MHz.hex
atmega1284.bootloader.unlock_bits=0x3F
atmega1284.bootloader.lock_bits=0x0F
atmega1284.build.mcu=atmega1284p
atmega1284.build.f_cpu=16000000L
atmega1284.build.core=sanguino

Note the upload protocol (stk500v1), note the fuses and note the core folder (last line).

• in the end, since the booloader from calunium worked for me, I did not try the one from maniacbug, which (from what I read on the arduino.cc forum) seems to be very popular and work very well;

To compile the code for Sanguino with ATmega1284P, some macros must be updated as well, by adding
defined(__AVR_ATmega1284P__)  to any defined(__ATmega644P__)

like this:

#if defined(__AVR_ATmega644P__) || defined(__AVR_ATmega644__) || defined(__AVR_ATmega1284P__) // sanguino

In the end, the program space is about 126K (compared to 62K in ATmega644P) and the available RAM is 16K (compared to only 4K in Atmega644P). Not a bad upgrade for only a few bucks more.

Note: ATmega1284 is not defined in avrdude.conf shipped with Arduino 22 or 23 (folder \arduino-22\hardware\tools\avr), but it is defined in Arduino 1.0.