How to know Scheduler state and which task is running?

Kernel
1

Hello,

Is it possible to know the request and grant signals that the scheduler gets/gives? Would it be possible to have a variable which says which task is currently running?

2

The question is a bit vague …
Which bigger problem do you want to solve ?

3

pxCurrentTCB is a pointer to the task currently running (pointer to the TCB of currently running task).

Not sure what you mean by:

4

I would like to know externally (via GPIO for example) which task is running. So, if I have 8 tasks, with 3 bits I want to know which one is currently executing.

5

In the source code for FreeRTOS are some ‘TRACE’ macros that are called at various time that can implement this. There is a macro that is called as a task is swapped in, that you could make set the GPIOs. (Would need to look in the code to find the exact name, which I don’t have convenient at the moment). You would define that trace macro in your FreeRTOSConfig.h

6

See the FreeRTOS trace hooks.

7

Add some code to traceTASK_SWITCHED_IN. Or put some code in vTaskSwitchContext or taskSELECT_HIGHEST_PRIORITY_TASK.

Or you could use Percipio Trace but I am not sure what you can use for free.

8

Those are good places to start. Thanks for the quick answer

9

There are also trace tools that will provide this information. This uses the trace macros to generate a complete trace including the information you want. There is also Segger SystemView, although I’m not sure of the detail that provides.