What's the c syntax to perform an 16-bit sum like: CCPR1 = CCPR1 + TIMER1; Note that TIMER1 wasn't defined by the 1687x.inc. Instead it was made as TIMER1H and TIME1L (each one 8 bits type). The same is true to CCPR1. Summarizing: How can I define or use a new 16 bit variable called TIMER1 that is formed by TIMERH and TIMERL (MSB and LSB)? (this code is for 16F877) See you guys, Beto.