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Capture accuracy F2812

Roman
Intellectual 360 points

Hello everyone!

I use capture module to mesure frequency (it's about 233 HZ).May be anybody can suggest how to improve accuracy of this module.Timer freauency is 9.375 MHz and i reset timer counter every capture happens.I get  about 0.2 % accuracy, but need better.

  • 0
    TI__Guru 57255 points

    Roman,

    I would check the crystal/oscillator which is used to derive the F2812's clock frequency.  You can check this be setting up the XCLKOUT to output via software and then check the error and stability of that pin.  If you can improve the stability and tolerance of the crystal, resonator or oscillator from which the F2812 derives its clock, the F2812 should get closer and closer to more accurate measurement.

    You may also want to take a look to see if there is any other circuitry (such as an op-amp, comparator, or buffer) to see what kind of delay (and therefore error) that circuitry would introduce to the system. 

    I would start by looking at the signal chain because it looks like the error is relatively large for such a relatively slow signal.


    Thank you,
    Brett