I have a pretty simple program that reads input from an XBee and writes output to a 16x24 matrix. The code works great on a ATMega328, but even though it compiles and loads just fine, will not do anything on a ATMega168. It’s not size (both compile to 5K).
I’ve moved the shield that the wiring is on back and forth. The XBee receives packets just fine on both. The 328 writes to the display, the other doesn’t.
To be honest, I haven’t dug into what’s going on, being lazy and asking first.