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Pulse counting and pulse duration measurement with PIC

Discussion in 'Embedded' started by Guest, Oct 11, 2006.

  1. Guest

    Guest Guest

    Hi To All,

    I have a model airplane in which I want to measure engine RPM and pulse
    duration measurement with a PIC 18F6680 series micro controller.

    The propeller on my airplane has a small magnet and I use a small hall
    effect sensor to detect rotation as one pulse per revolution. Output of the
    hall effect sensor is clean TTL Pulses that the frequency and the duration
    of the pulses changes as the propeller's rotational speed changes.

    I'm also trying to hack the radio control receiver and find the pulse stream
    correponding to the original pulse stream sent from the R/C transmitter. My
    R/C transmitter has 8 channels and it produce signal waveform as it is well
    explained in http://www.mh.ttu.ee/risto/rc/electronics/radio/signal.htm. I
    want the PIC controller to do is decode this multi channel pulse stream and
    create serial data coresspond to each servo channel position value like (
    111, 012, 222, 111, 211, 000, 121, 001).

    Can some one show me in PIC C18 compiler (I'm not assembler programmer) how
    to (1) measure RPM and (2) how to decode servo pulse stream in to array of

    Thank you.

    Harry Ja
    Guest, Oct 11, 2006
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  2. I did the pulse width measurements with a PIC16F628 using PIC Basic Pro and
    assembly. Unlike the transmitter, the receiver didn't have gaps between the
    channels. The end of one channel was the start of the next channel. I used
    timer 1 to do the measurements. The critical timing was done in assembly.
    The resolution was 800 ns per count with the PIC running at 20 MHz. The
    output of each channel was connected to a pin on the PIC.

    I don't have a website to post the source code to, but if you want the code,
    I could send it to you.

    Donald Harris, Oct 11, 2006
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