pwm question

[Marc]

I have a circuit which drives a led: a pic micro generates a pwm signal to the gate of a mosfet connected source-drain to a led and a resistor in series. I try to measure with adc the led current at the resistor pins but I see pwm waveform.
Iask how to know when pic generates pwm signal equal to 1 and when equal to 0 so that I can turn on adc when pwm waveform is 1.


Thank You

[nilsener]

Dear Marc,

the PWM is controlled by Timer2. Try to read the ADC in the ISR of Timer2. There is a 50:50 chance that the PWM signal changes from L to H when the Timer2 interrupt occurs. If it changes from H to L then it will not work.

[Marc]

I do not know exactly how pics work but I think there should be a register in which it is written if pwm is 1 or 0 so that I can control that.

[nilsener]

which PIC do you use?

[Marc]

18f4580