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Fix LFCLK initialization on nRF #85

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Merged
gmarull merged 2 commits into from
Mar 14, 2025
Merged

Fix LFCLK initialization on nRF #85

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ad4a7f9
fw/boards/asterix: fix LFCLK initialization
gmarull Mar 14, 2025
366cc81
fw/boards/asterix: remove sdk_config.h
gmarull Mar 14, 2025
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10 changes: 8 additions & 2 deletions src/fw/board/boards/board_asterix.c
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Original file line number Diff line number Diff line change
Expand Up @@ -152,10 +152,16 @@ void board_early_init(void) {
nrf_gpio_pin_set(15);
nrf_gpio_pin_set(16);

/* TODO: check that LFCLK actually comes up */
nrf_clock_lf_src_set(NRF_CLOCK, NRF_CLOCK_LFCLK_XTAL);
nrf_clock_event_clear(NRF_CLOCK, NRF_CLOCK_EVENT_LFCLKSTARTED);
nrf_clock_int_enable(NRF_CLOCK, NRF_CLOCK_INT_LF_STARTED_MASK);
nrf_clock_task_trigger(NRF_CLOCK, NRF_CLOCK_TASK_LFCLKSTART);
/* TODO: Add timeout, report failure if LFCLK does not start. For now,
* WDT should trigger a reboot. Calibrated RC may be used as a fallback,
* provided we can adjust BLE SCA settings at runtime.
*/
while (!nrf_clock_event_check(NRF_CLOCK, NRF_CLOCK_EVENT_LFCLKSTARTED)) {
}
nrf_clock_event_clear(NRF_CLOCK, NRF_CLOCK_EVENT_LFCLKSTARTED);
}
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@jwise jwise Mar 14, 2025

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this should time out after some time and sadwatch (or TODO for that) if LFXO fails to come up

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@gmarull gmarull Mar 14, 2025 •
edited
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Hmm, even nrfx doesn't time out:

https://github.com/nrfconnect/nrfx/blob/ad604db99489a3cce43620abeb3cf839a2a649b7/drivers/src/nrfx_clock.c#L496-L498

Assuming bootloader will leave WDT on, if this fails the system will reboot anyway. If this fails, we're in trouble as well (e.g. BLE won't work at all). Not sure if BLE SCA can be adjusted at runtime, so we could potentially fall back to a calibrated LF RC.

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@jwise jwise Mar 14, 2025

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Yeah, this was on previous Pebbles to mark hardware failure (usually water incursion). Boot cannot proceed but providing the correct error code explicitly (by triggering a sadwatch) can help diagnose the failure.

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@gmarull gmarull Mar 14, 2025

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I've added a comment for now if that's ok

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@jwise jwise Mar 14, 2025

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LGTM


void board_init(void) {
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