Need help with INTerrupts
I have a project that has a sensor connected to the analog pins of the microcontroller.
PIC18F6520 is the controller part number which I am using The sensor is sending a
train of pulses at a certain frequency. I would like to measure the length of time
the signal is high, and the period od the entire pulse so that I can measure the frequency and the duty cycle of the pulse.
I was thinking that I should implement a interrupt and two timers Timer0 and Timer1.
the timer0 can measure the time the pulse is high, and timer1 can measure the period of the pulse.
I know this is possible but I need your help. My question is from the code below. how will the timer know when the input pulse made a transition from high to low and when to stop the timer.
here is what I ahve thus far.
I have started interrupt and the timer0(the timer that will measure the high pulse).
I was wondering how to use the On inteerupt command that PBP comes. so whenever the interrupt comes I can jump into the ISR and begin measureing the pulse with timer0
CODE----------------------------------------------------------
Value VAR Byte 'value for how long the pulse was high.
TrisD = %11000000
On Interrupt goto ISR_INT
start:
if(PortD.7 = 1)&&(PortD.6 = 0) then
T0CON = %11000011 'Timer0 is turned on
INTCON.7 = 1 'Globale interrupt enabled
endif
if(PortD.7 = 0)&&(PortD.6 = 1) then
T0CON = %11000011 'Timer0 is turned on
IntCON.7 = 1 'Global interrupt enabled
endif
Goto Start
Disable
ISR_INT:
T0CON = %11000011 'Timer0 is turned on
'Timer0 prescalar to 16
'Timer0 increment on low to high transition
Value = TMR0L 'store the value of the lower 8 bits of TIMER0 into the Value variable
INTCON.1=0 'clear the timer0
Resume
Enable
