From the PIC16F877 data sheet section on the CCP module: "A PWM output... has a time-base (period) and a time that the output stays high (duty cycle). The frequency of the PWM is the inverse of the period (1/period)." In terms commonly used with PICs when using the CCP module for PWM, there is a period and a duty cycle. And if I recall corectly from my earlier reading, when the duty cycle equals or exceeds the period the output stays high. Dale -- It's a thankless job, but I've got a lot of Karma to burn off. On Thu, 9 Jan 2003, Sid Weaver wrote: > PWM doesn't have a "period". It has duty cycle and cycles. HPWM has duty > cycle and frequency. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.