So being that the PCAs first appeared in some of the more advanced 8051's from Intel it may not surprise you to learn that Intel has a detailed application note available that provides a whole lot of good info on programming PCAs. The app note has become known as the PCA Cookbook and can be accessed at the following link:

http://www.intel.com/design/MC...085101.PDF

Please additionally be aware that some newer MCUs with PCAs on chip may have a couple of additional features beyond those offered in the original Intel design. Some of these may be more options on how the central timer of the PCA is clocked. Due to this is is important to read the device data sheet for your MCU carefully to determine where it may be enhanced.

Michael Karas