Errata[68] CLOCK - nRF52810

RE: Errata[68] CLOCK - nRF52810

Vidar Berg — Thu, 15 Sep 2022 13:10:35 GMT

Hi,

Sorry, I forgot this detail about the errata. But please note that if you use Nordic SDK that rely on the 32MHz, then all protocols will always startup the external 32MHz crystal 1.5ms prior to when it's required, so even if the startup time is more than 400us this Errata 68 is not really a problem. Otherwise I think you will need to come up with a test verify to verify if the oscillator is stabilized after the EVENTS_HFCLKSTARTED event. You could, for instance, measure a PWM output signal while HFXO is being started.

RE: Errata[68] CLOCK - nRF52810

buja — Thu, 15 Sep 2022 12:46:48 GMT

Hi Vidar,

Thank you for your reply.

I am a bit confused, The errata says "EVENTS_HFCLKSTARTED may come before HFXO is started.", which conveys that EVENTS_HFCLKSTARTED cannot be used to confirm whether the HFCLK is started. Even if EVENTS_HFCLKSTARTED is 1, there are chances that the CLOCK is not actually started (that is what errata says).

So how can you use the statement in line number 7 to check if the HFXO has started.

while(NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

RE: Errata[68] CLOCK - nRF52810

Vidar Berg — Thu, 15 Sep 2022 11:20:33 GMT

Hello,

The startup time likely less than 400us, but you can try to measure it using the snippet below to be sure.

NRF_TIMER1->BITMODE = TIMER_BITMODE_BITMODE_32Bit << TIMER_BITMODE_BITMODE_Pos;
NRF_TIMER1->TASKS_CLEAR = 1;
NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
NRF_TIMER1->TASKS_START = 1;

NRF_CLOCK->TASKS_HFCLKSTART = 1;
while(NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
NRF_TIMER1->TASKS_CAPTURE[0] = 1;

NRF_LOG("HF Clock has started. Startup time: %d uS\n", NRF_TIMER1->CC[0]);

Best regards,

Vidar