app_timer2 assert in on_compare_evt after upgrade from SDK 16 to SDK 17

[eriknorth]

Hi,

After upgrading from SDK 16 to SDK 17 my device started to assert on app_timer2.c line 298:

ASSERT(app_timer_cnt_diff_compute(drv_rtc_counter_get(p_instance),
                                          drv_rtc_compare_get(p_instance, 0)) < APP_TIMER_SAFE_WINDOW);

This happens way more often when running without debugger/RTT.

I checked my app timer handlers and i could not notice that any of them would take too long time to finish. Have not measured tho.
Assert happens both while advertising and in connected state.
As soon as I switch back to SDK 16, everything is fine again.

Has something changed in sdk_config.h? Do I need to update some values?

Some details:

• device nrf52840
• running device as a peripheral
• s140 softdevice

/Erik

[Kenneth]

If you replace this line with SDKv16 then it works?

ASSERT(app_timer_cnt_diff_compute(drv_rtc_counter_get(p_instance),
                                          mp_active_timer->end_val & RTC_COUNTER_COUNTER_Msk) < APP_TIMER_SAFE_WINDOW);

How many app_timers are running, are they single shot or interval?

[eriknorth]

Hi Kenneth,

After replacing the the line 298 in SDKv17 version from SDKv16, it stopped asserting/crashing.

I am using two interval timers and one single shot timer.

If this is of any help, my project involves two parts - peripheral and central (also s140). And this issue is present only on peripheral.
Central seems to work fine after the upgrade.

/Erik

[Krzysztof Chruscinski]

Hi Erik,

can you provide your APP_TIMER_SAFE_WINDOW_MS and APP_TIMER_CONFIG_RTC_FREQUENCY values? 

Also can you log or somehow capture what are the values or NRF_RTC1->COUNTER and NRF_RTC1->CC[0] when assert occurs?

Krzysztof

[eriknorth]

Hi Krzysztof,

Sorry, for the delayed answer.

APP_TIMER_SAFE_WINDOW_MS = 300000
APP_TIMER_CONFIG_RTC_FREQUENCY = 0

NRF_RTC1->COUNTER = 1028836
NRF_RTC1->CC[0] = 1028837

/Erik

[eriknorth]

Hi again,

I just tried SDK 17.0.2 and I am still experiencing the issue. When I replace it with the line suggested by Kenneth, it starts to work.

I tried to change the APP_TIMER_CONFIG_RTC_FREQUENCY to 1 but that did not fix the issue.
If understand this correct then in my case when it calculates the difference between counter and CC, it gets -1 and that value is unsigned so it goes to UNIT32_MAX that is than masked with 24bits so that it would get a value in the range of RTC counter.

Is this how it should be, that this is an illegal value and should assert?
Do you have guesses why does my program end up in this scenario?

Thank you,
/Erik

[Krzysztof Chruscinski]

Can you try to enable debug logging in app_timer by setting APP_TIMER_CONFIG_LOG_LEVEL to 4 and  NRF_LOG_DEFAULT_LEVEL to 4 and provide logs when issue occurs?