Ultralit Interrupt problems

[willnick55]

Posted on August 29, 2008 at 15:43

Ultralit Interrupt problems

[willnick55]

Posted on August 28, 2008 at 17:27

Hi,

This is my first posting here. I am an analogue engineer really but have recently started using an ST7 in a regulator application. I am a software novice.

I was getting on ok with the project until I started getting glitches in the PWM output, with long pulses being produced. This was tracked down to the fact I was setting the ATR value at the same time an a compare occured, now and then.

The solution to this I am told is to use an interrupt to syncronize setting ATR to the overflow of the counter.

However I have been trying this and using Interruot 9 is causing problems. The ATR values is incremented and the frequency output is increased until the frequency increase stops (at too low a frequency) and the programme malfunctions.

I have no idea why this is happening and hope someone can spot the problem.

Thanks,

Nick

[willnick55]

Posted on August 29, 2008 at 15:43

I think this is happening due to time delays in the interrupt routine. The PWM timers runs up to about 90Kz, then stops. I was trying to get up to 300KHz.