Possible bug in nrf52832 LFCLK

[KLWP0101]

[Bug Report] Possible bug in nRF52832 engineering release B. When LF XTAL oscillator is started, no event is generated.

NRF_CLOCK->LFCLKSRC = CLOCK_LFCLKSRC_SRC_Xtal;
NRF_CLOCK->TASKS_LFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0)   { };      // STUCK HERE FOREVER!!

The oscillator is actually started but no event is generated.

[Susheel Nuguru]

updated with code that worked (29.01.2016)

Maybe it needs one clk cycle or two between selection of the clock source and starting the lfclk, try this below

NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
NRF_CLOCK->LFCLKSRC = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
__DSB();     //<-- This will wait until write buffers are emptied.
NRF_CLOCK->TASKS_LFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0)
{
}

i do not have engineering sample B to test it with. If the above code works, then i should ask someone here to test out why the event missed.

[Susheel Nuguru]

Then RK got it right, it was for sure a write buffer issue. Good that it worked. I have created an internal ticket to update the functional changes document to use memory barriers. Hopefully infocenter will be updated soon.

If there is nothing else to do in this thread then can you please accept my updated answer by clicking ✓ on the left side of it so other see this thread as Green.