Hey Grey, how are you doing air fuel ratio? Do you have a wideband o2 sensor? Is that what the fuel table is for?
Re: arduino, it is just an affordable ($15 for the board/cpu/and all components) and open source hardware platform with a lot of people working on it to improve it and do new things with it all the time. It is based on the atmega168 and the boards currently in curculation are easy to program with the provided IDE (also open source). the IDE (written in Java) supports a c-like syntax, and figures out what to include and link to make the binaries based on what your code references. But all of wiring and AVR and GCC, and even assembler are still at your fingertips (I would save the assembler for spots that need optimizing in performance or size).
So the platform is easier for pic newbies, has a huge user base, can do anything an atmega168 can do, usually in an easier fashion than the dropping into a lower level because someone has put a library together, but the lower levels are still there for more advanced users. Also it doesn't require extra programming hardware. But certainly an experienced person could solder a few wires to an atmega168 on the cheap and reuse the code.
But doing everything in assembler to get it on a ATTiny2313? I don't get that. What you gain in size and performance, you usually lose on development and maintence and features. Those ATTinys are like $2.50, and an atmega168 chip is like $4. Oh well, no accounting for taste
Glad you are into it.
Let me know how you figured out air fuel if you please.