CCP Module How to ?

[Darrel Taylor]

Hi capitano,

Could be a simple problem.

You're starting off with the Capture triggering on the rising edge, and State = 0
CCP1CON = %00000101

On the first interrupt, it starts the timer and changes the State to 1. But I think at this point you also need to change the capture mode to trigger on the Falling edge.
CCP1CON = %00000100

On the next time through the interrupt, take the reading, clear the timer and State, then set it to trigger on the Rising edge again.

This would measure a HIGH pulse. To measure the LOW pulse just reverse the Rising/Falling edges.

Something like this:

interr:
'************************************
'Interrupt Speed

    If pir1.2=1 then
        If state=0 then
            T1CON.0=1 ' Enable Timer 
            CCP1CON = %00000100   ' Next trigger is Falling edge
            pir1.2=0  ' Reset Capture Flag 
            state =1
        else
            Speed.lowbyte = CCPR1L 
            Speed.highbyte = CCPR1H 
            ' Store the captured value in period variable 
            T1CON.0=0 ' Timer is OFF 
            CCP1CON=0 ' Capture is OFF 
            TMR1L=0   ' Reset Timer 
            TMR1H=0   ' Remember Timer is OFF 
            pir1.2=0  ' Reset Capture Flag 
            CCP1CON = %00000101   ' Next trigger is Rising edge
            state=0
        endif
    endif
Resume

HTH,
   Darrel