On 04/10/11 02:01, peter green wrote: > What intterrupts are you expecting? RB0 interrupt-on-edge. > Your code seems to talk about a > timer interrupt but doesn't seem to actually enable the timer interrupt. That's in the code I trimmed out for the sake of brevity :) It uses TMR0 to measure the delta-T between pulses, and also (later on)=20 for the time-out. > As for the int0 intterrupt it looks to me like you may have RB0 set as > an analog input. Yep, that's what it was. Well, I feel thoroughly stupid now....! Solution: "ADCON1 =3D 0x7F;" Thanks, --=20 Phil. piclist@philpem.me.uk http://www.philpem.me.uk/ --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .