Question on adding Schmitt trigger to frequency measurement PASM2 code

Dodwin

Hi, P2 newbie and first time poster here. I cobbled together this frequency measurement code based on one of @JohnnyMac 's helpful posts. I'm having trouble adding a Schmitt trigger function to the input pin. I'd be very grateful for any ideas how to do this. Thanks, Derek

pub MeasureFreq( pin, NumPeriod ) : FreqEst | result, tix
' Simple freq measurement, counts number of rising edges in the interval (seconds),
' FreqEst is computed in milliHz
' pin ' pin on which to measure frequency
' FreqEst ' estimate of frequency in milliHz

org
fltl pin ' clear pin
wrpin #P_PERIODS_TICKS, pin ' count tics
wxpin NumPeriod, pin ' in NumPeriod cycles
wypin #0, pin
dirh pin

    .loop   nop
            testp pin wc
    if_nc   jmp  #.loop
            rdpin result, pin

end

FreqEst := muldiv64( NumPeriod*1000, clkfreq, result )

evanh

wrpin ##P_PERIODS_TICKS | P_SCHMITT_A, pin ' count tics

Dodwin

Thanks evanh! I'll give it a try.

Dodwin

That worked beautifully! Thanks much!!

evanh

Cool.

There's a whole section of these symbols at the end of the Spin2 docs. However, it's not always obvious how they can be combined. Understanding what hardware is being controlled (Documented in the Silicon Docs) is probably the only way to know what's right.