I cant find anywhere if, or which, timers may be used with the ethernet shield and ethernet.h. The reason I ask, I am successful at explicitly sending a message and then waiting for a reply in 'main' code. As soon as I try to put the ehternet messaging in an attatched timer interrupt, things no longer work and it doesn't appear to return from the interrupt. I've stubbed code in that should print acknowledgment after a return, but it never happens. I've tried using timer1 and also timer3 as the attatched interrupt timer. I have a Mega2560 R3
What am I missing/over looking?