Post by thread:Precise frequency measurement

SendTo: spam_OUTpiclistTakeThisOuTmitvma.mit.edu Hi PIC gurus! A friend of mine needs accurate frequency measurement in the range cca. 10 Hz - 250 KHz, with at least 3 digits precision (ie. 48.035 Hz). I remember there were threads about frequency counters some time ago. Does someone of you, gurus, have any suggestions, piece of code, pointer, anything related? TIA, max .....mauricioKILLspam@spam@arne.si

> Hi PIC gurus! > > A friend of mine needs accurate frequency measurement in the range cca. > 10 Hz - 250 KHz, with at least 3 digits precision (ie. 48.035 Hz). I that's a 5 digits readout, although it might be imprecise :) > remember there were threads about frequency counters some time ago. > Does someone of you, gurus, have any suggestions, piece of code, > pointer, anything related? look at my home page, there is a frequency meter based on an idea taken from the PIC application notes. Data is fed into the prescaler and the counter, so as to implement a 16-bit counter, and counting is enabled for a fixed time. After that, an output pin is used to toggle the prescaler's input and cause it to overflow, so that the residual count can be read out. Luigi

For something like that you'll need a really stable and accurate frequency reference. If it's a short term need it might be best to just rent a good counter with a recent calibration. On the other hand, for a stable reference Elektor once had an article on a DCF77 receiver that had a stable frequency output referenced to DCF77. I'm ignorant about where arne.si is but if you're within range of the transmitter that might be an option. Aaron Sliwinski sliwinskia-cos3KILLspamkaman.com >A friend of mine needs accurate frequency measurement in the range cca. >10 Hz - 250 KHz, with at least 3 digits precision (ie. 48.035 Hz). I >remember there were threads about frequency counters some time ago. >Does someone of you, gurus, have any suggestions, piece of code, >pointer, anything related? >max >.....mauricioKILLspam.....arne.si