Dear Russell and other forum members,

I have set the highest priority lelvel for the timer 1 interrupt which is taking care of zero cross detection and sending firing pulses. I am aware of the fact that P89V51RD2 supports four level interrupt priority scheme using two regiters IP0H and IP0L. I made set the bit corresponding to timer 1 to 1 in both the registers leaving all other bits 0. i.e interrupt 1 has highest priority and rest of the interrupts have lowest priority but still the flickering is there.

My Timer 1 ISR code can be found here.

http://www.8052.com/forum/read.phtml?id=81818

The flickering which is occuring is not a minor flickering that can cause due to 100us firing time variation but it is too much flickering Thus cause seems to be something else than 100us firing time variation.

Friends, I have been banging my head with keil since morning 8:00 am it is already 06:00PM but the problem is still not solved. Thanks for reading my post.

Regards,
Prahlad Purohit