PWM Programming in C

A PWM circuit can be made easily with a counter. Make a counter that counts from 1 to 100 (for instance) over and over. Your PWM value is a number between 1 and 100. Let's say you want a 25% duty cycle. While the count is between 1 and 25, you output a one (motor on). While the count is between 26 and 100, you output a zero (motor off). It works the same for any variable PWM value that you want.

You will also need to make the counter so that it counts at the correct frequency for your motor. You can do this with a second counter that controls when the first counter increments.

If you have been programming or know how to program the 16F877A in assembly language then may be you can convert some of the codes at the below link into the C -paradigm: http://www.piclist.com/techref/microchip/16f877adsamp.htm

Goodluck