LAUNCHXL-CC1312R1: I2S Blocking

Hi David,

As stated in the code example, any use of blocking call is illegal from a Hw interrupt callback context. This because when handling an interrupt, a blocked called can potentially block the system inside a callback and not allow any other task to run. The best way to signal an event from a callback is to:

1) create a semaphore in your main application

2) Post the semaphore from the callback to unblock a task pending on that semaphore

3) the task will be unblocked and will execute the potentially blocking call from a task context instead of interrupt context

Regards,

Fausto

Hi David,

you can use either the TIRTOS7 semaphores (documentation here) or the  Posix-semaphores (documentation here) which are a OS-independent wrapper of both freertos and TIRTOS7 semaphores and can make your code more portable across OSes.

Here is a simple example on how to use the SemaphoreP Posix-semaphores in binary mode (the semaphore can only count up to 1, use the regular type of semaphore instead if you want it to be able to count to higher number):

#include <ti/drivers/dpl/SemaphoreP.h>

static SemaphoreP_Struct mySemaphore;

void myCallback (void) {

    // Post semaphore and unblock the blocked task
    SemaphoreP_post(&mySemaphore);
}


void myTask(void) {

    // Create a binary seamphore and initialize it to 0
    SemaphoreP_constructBinary(&mySemaphore, 0);
    
    while(1) {
        // Pend for the semaphore to be unblocked by the callback
        SemaphoreP_pend(&mySempahore);
    
        // Finally execute potentially blocking call here
        // ex. I2S_stopRead() or I2S_stopWrite()
    }
    
}

Regards,

Fausto