Capture woes...

[ardhuru]

Yes, I understand the internal oscillator wouldnt be extremely accurate. I did try it with a 4MHz external crystal, same readings.

The test source for square waves is a pic based instrument called 'Superprobe'; a great little instrument, the plans for which are available here: http://members.cox.net/berniekm/super.html

I did suspect the accuracy of the Superprobe, but checked it with a scope, and its spot on.

So, the issue boils down to my having messed up the capture code in some indeterminable way; or my understanding of the prescalers being totally off

The wrong results I get are very consistent for a given frequency. But, the ratio of observed readings to expected ones is not the same for different frequencies. Another mystery.

Anand