Ok, here's a copy of the modifications I made.  You'll have to change F_CPU in constants.h or set it in your IDE.  I've updated to interrupt.h from signal.h, removed delay.h and now use avr-libc's util/delay.h and switched from cbi/sbi to <reg> &=/|=.  I've also added the proper registers for ATMega88's.  To port to another CPU you just need to add the #defines in constants.h  Hopefully this works

Jason

I've been working on updating ip-bus v4 for the newer versions of avr-libc.  I've removed all the cbi/sbi macros, switched from signal.h to interrupt.h, and I'm working on the delay routines.  Is delay1() actually 1us?  Switching to avr-libc delay routines will make frequency changes much simpler as they calculate the delays at compile time and are fairly accurate from what I read...  Also I've read in the forums/code a quite a few differences about the timings for the bus, is there a up to date list of times for StartBit, 1, 0, and ACK?

I'm also looking at using the internal comparator in the ATMega88 instead of the LM339, is this possible?

Jason