Dear all,

Thanks for your time.

The issue has now been resolved - instead of just sampling one period time I have now increased the sample size to 5 and display the average. Great. Now my code + MCU can match any super duper frequency meter.

On the issue of crystal time base, I think I did not clarify enough - the 1 Sec interval was ONLY the interval of display update. The period aqcuisition is directly with the PCA event interrupt and inside the ISR I write it to a RAM location for reading at my liesure.

ANyway the pointers to the GPS time base stuff WAS interesting and can come in handy for another project that is now currently on.

Thanks. One and all.

Raghu