HFXO does not work on nRF52832

[silvio3105]

Hi,

I cannot start HFXO on nRF52832. I'm using 32MHz crystal TSX-3225 32.0000MF20X-W0(from Mouser) wtih 12pF caps UMK105CG120JV-F(also from Mouser).

Checked with beeper on multimeter, no shorts between pins and between pin and GND.

Looks ok on MCU pin side(QFN package).

This is code

int main(void)

{

    NRF_LOG_INIT(NULL);

    NRF_LOG_DEFAULT_BACKENDS_INIT();

    NRF_CLOCK->TASKS_HFCLKSTART = 1;

    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);    

And PCB

I'm out of ideas.

[Kazi Afroza Sultana]

Hello,

We have an [68] CLOCK: EVENTS_HFCLKSTARTED can be generated before HFCLK is stable errata that could be relevant to your issue. If EVENTS_HFCLKSTARTED starts before HFCLK is started.

Can you check the Crystal start-up time of your 32MHz?

[silvio3105]

I can but I'm not sure how.
It could be this problem since sometimes(very rare) app starts but BLE advertise does not work. App works but I cannot find the device in Nordic's mobile app.
I have QFAAE0 chip.

Btw. App stucks at while loop because event is zero. How errata 68 relates with this problem? 

[rmptxf]

We also run into a similar issue, and the start time was more than a 1ms on best cases (not even fixed).

What should we do in that case of high start time?

[rmptxf]

This is how we get the startup time on NCS.

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;

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

[hmolesworth]

Most useful, we will adopt this. For other users it may be helpful to do the measurement in uSecs:

   NRF_TIMER1->PRESCALER = 4; // Time in uSecs when using 1MHz timer clock. fTIMER = 16 MHz / (2^PRESCALER)