Have a read through the C5 firmware sketch, there really isn't a whole lot in there for modification in it's current state unless you add parts to the unused I/O pins on the ATMega168.
https://github.com/jdslabs/c5_v100_MasterFirmware104/blob/master/c5_v100_MasterFirmware104.ino (Opens in a viewer)
I can see people easily adding that Apple style slow breathing glow to the power LED.
You'll need a
PogoPin board like this if there is not enough room to solder header pins directly to the board.
You will also need an ISP Programmer to put the code there, either an
Arduino Board, a
LauchPad MSP430 or anything like the
Sparkfun AVR Programmer.
The
DS1882 dual log digital pots from Maxim talk I²C, two wire addressable devices have to be controlled by an I²C master which is what the ATMega168 is doing.
From what I read in the source code, the ATMega168's functions are:
Turns on Power
Reads saved Gain & Volume values from an EEPROM.
Sets Gain
Sets Volume
Monitors Battery Low
Changes LED's to reflect low battery or normal condition.
The only libraries loaded at compile time are Wire.h for the I²C functions and EEPROM.h for talking to the EEPROM.
I was hoping for more but that is all the 'duino chip does... around the Arduino community they would say that the ATMega168 was just put in there for "Blog Cred." (HaD joke...
)
My 2 cents.