Hi,

I am stuck with a problem of detecting a zero crossing pulse from a zero crossing circuit CA3059. This is basically used to drive a triac for power application and acts as a switch to the equipment ensuring that pulse to triac starts at phase zero.

My problem is that i am using the zero crossing circuit to detect the zero crossing and then giving a led a sequence of increasing duty cycle pulses to act as a dimmer.

For this i need help in the code of the PIC controller. I am using 16F877 series of the PIC. I do not want to use the interrupts and for now have this code to detect the zero crossing.

TRISB.2=1
start: if portb.2 EQ 1 then loop
goto start

I understand that this loop takes time and does not detect the pulse from CA3059 which is just .5 ms wide.

Please suggest me an alternative.

Thanxs in Advance.

Ameen