Just a guess but i can't see clrwdt instruction anywhere and you've got the wdt switched on ----- Original Message ----- From: Saurabh Sinha To: Sent: Friday, March 31, 2000 09:44 Subject: ISR is never called > Hi, > > Another problem, with my filter program, the ISR never gets called! Its > supposed to be called every 1/300 s, at which PORTB is to be read. > > [I have used a intial TMR0 value of 47 and a prescaler of 16 to get the > 1/300 s delay.] > > Any ideas?? > > Thanks for your replies. [past & future] > > Regards, > > Saurabh >