Allan, Jan-Erik gave me the answer. You are correct about the defines=20 being in the PIE registers. It is fixed and it compiles correctly. Now I=20 just need to know how to use the interrupt routine. That is this one: void Interrupt(){ if (TMR1IF_bit){ TMR1IF_bit =3D 0; TMR1H =3D 0x0B; TMR1L =3D 0xDC; //Enter your code here } } I'm getting there. Thanks, rich! On 7/19/2014 1:50 PM, Allen Mulvey wrote: > I'm afraid I don't have an XC8 compiler. I would double check the defines= .. > These have the letter 'I' in them which can easily be mistaken for a digi= t > '1' in many fonts. TMR1IF_bit is the interrupt flag bit. TMR1IE_bit is th= e > interrupt enable bit. > > Some PIC16s (16F88x) use notation like PIE1.TMR1IE (PIE1.B0) and PIR1.TMR= 1IF > (PIR1.B0). These are in the peripheral interrupt registers. > > Allen > >> -----Original Message----- >> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .