Get Tick Count From ISR

[Roei]

Hi,

I have an issue of watchdog in my application.

I think it may occur due to an interrupt (NFC trigger), which calls the function xTaskGetTickCount() instead of xTaskGetTickCountFromISR(), while other task already entered the critical section using xTaskGetTickCount(). Therefore - the interrupt is stuck on the mutex until watchdog occurs.

Is that make sense? If so - using xTaskGetTickCountFromISR() during interrupt context can solve my problem? How?

Thanks!

[Susheel Nuguru]

Can you please give me more context of the callstack that calls xTaskGetTickCount inside an interrupt? Is this Nordic SDK code or application specific code?

[Roei]

Sure.

We are talking about event which triggers NFC_T2T_EVENT_FIELD_ON.

After that, my application writes an event, stops current advertising, perform some checks and start new advertising.

One of the checks is that xTaskGetTickCount is under a specific value.

In that case, I think I need to use xTaskGetTickCountFromISR().

[Susheel Nuguru]

You should do something like below in your app

if (__get_IPSR() != 0)
{
    xTaskGetTickCountFromISR()
} else 
{
    xTaskGetTickCount();
}

[Roei]

I've noticed that FromISR functions don't use critical sections.

Isn't that problematic?

[Susheel Nuguru]

All FromISR based functions that push the context to a queue does not need any critical sections while pushing onto the queue. The rest of the FromISR functions that are synchronous do use critical sections using portSET_INTERRUPT_MASK_FROM_ISR