Allan, I'm using the MicroChip XC8 compiler. I just looked through the=20 macros in the pic16f684 include file and the code should work. Would you=20 please take a look at this code section? The values that are being=20 flagged are the TMR1IF_bit and TMR1IE_bit definitions. Here is the code=20 with the flagged sections commented out: void InitTimer1(){ T1CON =3D 0x31; //TMR1IF_bit =3D 0; TMR1H =3D 0x0B; TMR1L =3D 0xDC; //TMR1IE_bit =3D 1; INTCON =3D 0xC0; } void Interrupt(){ //if (TMR1IF_bit){ //TMR1IF_bit =3D 0; TMR1H =3D 0x0B; TMR1L =3D 0xDC; //Enter your code here //} } I can't see what is wrong as these definitions are in the include=20 file. With these statements commented out the code compiles. Thanks, rich! On 7/19/2014 10:53 AM, Allen Mulvey wrote: > What compiler are you using? This code is for MikroC. You may have to > translate a few things. For instance, they may express things like > "TMR1IF_bit" differently. These are PIC specific and not a part of standa= rd > ANSI C so each compiler developer is free to define them as they see fit. > > Allen > >> -----Original Message----- >> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of >> Richard R. Pope >> --=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 .