PIC Frequency Counter: Fixing the pulse-width problem (and getting beyond 100 MHz)

The PIC frequency counter can easily fail measuring frequencies when the signal pulse widths are too short. This happens in all firmware versions, even the original one. The most likely case are frequencies from 1 to just below 4 MHz. Frequencies above and below are usually ok. This video describes why it happens and how a firmware change fixes it (and, unexpectedly, boosts the top frequencies the frequency counter can handle)

0:00 The problem 1:04 Why it happens 3:05 Range 400K to 4MHz 5:07 How the prescaler works 7:42 Old firmware test 8:48 New firmware test 9:23 Good and bad duty-cycles 11:14 Period is another problem 12:53 High and hex frequencies 14:12 Proper high frequencies 15:01 Changes summarized

Download the new firmware from here:
https://github.com/TheHWcave/PIC-freq.counter-modification/blob/master/HiRes_Freq_RPM1234_Event_counter/HiRes_Freq_RPM1234_Event_counter_v4.hex

Or contact me by email (see About ... page). If you send me your PIC-chip, I program it for free, you pay just the return postage. I can also send you a new programmed chip for slightly more. Please contact me before(!) sending your chip.

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