WatchDog feeding from bootloader to application and softdevice

RE: WatchDog feeding from bootloader to application and softdevice

Einar Thorsrud — Tue, 04 Sep 2018 12:52:06 GMT

I see. Thank you for letting us know how you solved it.

RE: WatchDog feeding from bootloader to application and softdevice

Catalin — Tue, 04 Sep 2018 12:35:05 GMT

Hi,

The problem was by calling the nrf_sdh_enable_request() from the init_hook function from FreeRTOS. Calling this function before starting the FreeRTOS the issue was resolved.

Thanks for suggestions.

RE: WatchDog feeding from bootloader to application and softdevice

Einar Thorsrud — Tue, 04 Sep 2018 12:09:57 GMT

Ah yes, I did not spot that in your code snippet. It seems strange to me, then. I have not been successful in reproducing this issue on my side.

I simply copied in your init_watchdog() function and called it in the beginning of main() in the debug bootloader for SDK 15 (\examples\dfu\secure_bootloader\pca10040_ble_debug). Then I used the pre-compiled application ble_app_buttonless_dfu_without_bonds_s132_with_setting_page.hex from the SDK distribution. I can see from the RTT log and LED's that the application starts as expected and starts advertising before it is reset every 30 seconds (due to not feeding the watchdog). So everything seems OK in this test.

Can you tell me more about what you are doing, or (even better) upload a bootloader and application that demonstrate this issue? Also, do you have a 32 kHz xtal on your board (not that I think it should mater)?

RE: WatchDog feeding from bootloader to application and softdevice

Catalin — Tue, 04 Sep 2018 11:33:21 GMT

Hi,

As you can see in the code, the timeout is set to 30 seconds. We measured that after this timeout the board is rebooted.

RE: WatchDog feeding from bootloader to application and softdevice

Einar Thorsrud — Tue, 04 Sep 2018 09:37:16 GMT

Hi,

The problem here is most likely that you have a too short WDT timeout. nrf_sdh_enable_request() calls sd_softdevice_enable() internally, which can take quite some time as it will block until the 32 kHz clock is started, so you need to account for that if you start the watchdog before the call to nrf_sdh_enable_request(). As you can see from the nRF52840 CLOCK electrical specification, the (optional) 32 kHz xtal oscillator startup time alone is typically 0.25 s (tSTART_LFXO).