[nRF52] sleep time passing too quickly

[WhiteHare]

I'm using utime.sleep_ms(1000) to create a one second delay between packet transmissions by an nRF52840, and yet the delay seems to be lasting only about 250ms instead. Perhaps something is waking it up prematurely?

Is there a better way to create a more accurate delay?

[uCTRL]

Is your main CPU oscillator configured correctly?
Check to see at frequency CPU is running, machine.freq().