LFCLK timer slows to a crawl

[Steve H]

I have a program which uses two timers to flash an LED, alternating between flashing once every 5s for 15s, then once every 0.25s for 15s.

If I run this on the nRF52-DK with the external LFCLK, it works fine (15 hours and counting).

If I run this on a nRF52-DK with the internal RC, calibrating every 4s, it seems to run fine.

If I run this on a BMD-300 with the internal RC, calibrating every 4s, within 5 minutes it suddenly slows to a crawl and the event handler only fires once every few minutes.

Any thoughts as to where the problem may lie?

Edit: so far as I can tell, the timer isn't overflowing. It's ticking every 0.125s. No Softdevice.

[Steve H]

The BMD-300 has worked fine with an external crystal for about 18 hours.

[Hung Bui]

This is very strange. You are telling you can see the TICK event happens normally but not the COMPARE event ? If you print out counter value when you have a TICK , what do you see when it passes the CC value ? May it have anything to do with your code ? Could you simplify the code down and test, maybe simply use (modify if needed) RTC example for testing.