R. I. Nelson wrote: > Bill & Pookie wrote: > > R. I. Nelson wrote: > > > Using a basic compiled program using a for-next loop, a flash PICchip. > > > can I expect to get a pulse every 55 ms. or about 18pulses per second? > > > > Not sure where you get the 55ms from, but 55ms/18hz is the timer > > interrupt frequency of the PC (personal computer) and should not have > > any effect on pic except for maybe reading or writing to the pic from > > the PC. It is a PC thing. > > 55ms (or 55.55555ms to be more exact) is about 18 pulses per second. Actually, if you're trying to emulate a PC, it's 18.2065096768466 pulses/sec, or 54.9254095238095 ms period. Convenient numbers, huh? :-) It's derived from the original PC CPU clock, which was a standard 14.31818 MHz crystal divided by three to generate 4.772727 MHz. This was subsequently prescaled by a factor of four and then divided by 65536 in a timer chip to generate the 18.2 Hz "tick" interrupt. If you want 55.55555 ms, that's *exactly* 18 pulses/second. -- Dave Tweed -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist