# Detect calling context (ISR or task) **URL:** \ **Category:** Kernel\ **Tags:** debug\ **Created:** [April 28, 2022, 5:38am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939 "2022-04-28T05:38:38Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![CharlesBl](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@CharlesBl](https://forums.freertos.org/u/CharlesBl)\ **Post date:** [April 28, 2022, 5:38am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/1 "2022-04-28T05:38:38Z")
Hello I need to provide a way to an external library to stop timers. The problems is that it call it from interruptions or not. In my stopTimer function, that I need to provide, if I’m calling xTimerStopFromISR or xTimerStop in the wrong context, I’m going into an error. Would you have a solution for this? Maybe I’m not seeing another way of doing it… Thank you CBL ---
**Author:** ![hs2](https://avatars.discourse-cdn.com/v4/letter/h/a4c791/32.png) [@hs2](https://forums.freertos.org/u/hs2)\ **Post date:** [April 28, 2022, 6:20am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/2 "2022-04-28T06:20:10Z")
What if following the FreeRTOS convention and provide `stopTimer` and `stopTimerFromISR` ? ---
**Author:** ![CharlesBl](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@CharlesBl](https://forums.freertos.org/u/CharlesBl)\ **Post date:** [April 28, 2022, 6:43am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/3 "2022-04-28T06:43:22Z")
Thanks for your answer. Sadly, I can’t modify the library that is calling stopTimer ---
**Author:** ![hs2](https://avatars.discourse-cdn.com/v4/letter/h/a4c791/32.png) [@hs2](https://forums.freertos.org/u/hs2)\ **Post date:** [April 28, 2022, 7:42am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/4 "2022-04-28T07:42:48Z")
Ahh … you’ve to provide a callback with a fixed API… To the rescue some ports as Cortex-M3/4 provide `xPortIsInsideInterrupt()` in `portmacro.h` which can be used to detect ISR context. AFAIK some other 3rd party libs use this mechanism to provide generic APIs, too. ---
**Author:** ![CharlesBl](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@CharlesBl](https://forums.freertos.org/u/CharlesBl)\ **Post date:** [April 28, 2022, 9:20am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/5 "2022-04-28T09:20:42Z")
Exactly… Thank you, that should do the job! I am using an STM32L746 so it should be Cortex M4 but I can’t find it in my portmacro.h. I will dig into this! Thank you for your help! ---
**Author:** ![aggarg](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/aggarg/32/4245_2.png) [@aggarg](https://forums.freertos.org/u/aggarg)\ **Post date:** [April 28, 2022, 9:57am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/6 "2022-04-28T09:57:55Z")
> [@CharlesBl](#): > > I am using an STM32L746 so it should be Cortex M4 but I can’t find it in my portmacro.h. Here it is - [https://github.com/FreeRTOS/FreeRTOS-Kernel/blob/main/portable/GCC/ARM\_CM4F/portmacro.h#L172](https://github.com/FreeRTOS/FreeRTOS-Kernel/blob/main/portable/GCC/ARM_CM4F/portmacro.h#L172) ---
**Author:** ![CharlesBl](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@CharlesBl](https://forums.freertos.org/u/CharlesBl)\ **Post date:** [May 12, 2022, 8:45am UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/7 "2022-05-12T08:45:28Z")
Thank you for your help, I have included it inside my portmacro.h and it works perfectly! ---
**Author:** ![simonjwright](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/simonjwright/32/4770_2.png) [@simonjwright](https://forums.freertos.org/u/simonjwright)\ **Post date:** [May 18, 2022, 7:19pm UTC](https://forums.freertos.org/t/detect-calling-context-isr-or-task/14939/8 "2022-05-18T19:19:10Z")
The identical function could be made available for the M0, if anyone wanted it enough