Hi everybody,

I am facing a problem with PIC32 port when I try to use queues. I got a simple application, only one task, one queue. There are correctly initialised (task and queue handles aren't null), vTaskStartScheduler() is called, then my task tries to receive a message from the queue with xQueueReceive().

I get stuck in vListInsert(), but :

1. My stack task doesn't overflow (I use method 2 for stack checking and vApplicationStackOverflowHook() is never called)

2. I don't think I have trouble with interrupts priorities : Kernell priority is 1, max interrupt priority is set to 4. Plus, I don't have used any other interrupts than those used for the kernell.

3. When xQueueReceived() is called, the scheduler is running (xSchedulerRunning = 1 and uxSchedulerSuspended = 0) but in vListInsert(), scheduler is suspended (is that ok ?). Actually it is suspended when calling vTaskSuspendAll in xQueueGenericReceive().

4. Queue has been initialised, no pending message.

Then, a bus exception is thrown (DBE). I have the same problem if I create a second task that put a message into the queue.

If it could help, I am using XC32 v1.11. I can reproduce the problem with MPLAB Sim and when I am debugging with a Digilent Cerebot MX7ck board with built-in licensed debugger.

As your application is so small, please post the code. Make sure to enclose it with the Codify Text tags (button just above the text entry box in the forum).

- Main():

int main(void) 
{
    vSetupHardware();

   Create_Ressources_OSTracing();

    vTaskStartScheduler();

    return 0;
}

- Create_Ressources_OSTracing():

ErrorCode_t Create_Ressources_OSTracing (void)
{
ErrorCode_t ErrorCode = {0};
#ifdef OS_TRACE
// 1. Create Task
if((ErrorCode.Code&ERRCODEMASK) == CODE_000_NO_ERROR)
{
if(xTaskCreate(_OS_Trace_TaskHandler,
   "RTOS Trace Task",
   STACKSIZE_OS_TRACE,
   NULL,
   PRIORITY_OS_TRACE,
   &TASK_OSTracing) != pdPASS)
{
ErrorCode.Code = LAYER_Service | TASKID_OSTrace | CODE_002_MEMORY_ALLOCATION_ERROR;
}
}

// 2. Create Message to Send Queue
if((ErrorCode.Code&ERRCODEMASK) == CODE_000_NO_ERROR)
{
Q_OSTracing = xQueueCreate(MAX_MSG_Q_OS_TRACE, sizeof(OS_TRACE_Msg_t));
if(Q_OSTracing == NULL)
{
ErrorCode.Code = LAYER_Service | TASKID_OSTrace | CODE_002_MEMORY_ALLOCATION_ERROR;
}
else
{
#if __DEBUG
vQueueAddToRegistry(Q_OSTracing, "OS Tracing Queue");
#endif
}
}
#endif
return ErrorCode;
}

- The task - _OS_Trace_TaskHandler():

void _OS_Trace_TaskHandler (void * pvTaskParam)
{
OS_TRACE_Msg_tTraceMsg;
OS_TRACE_Time_tTraceTime;

vTaskDelayMs(2000);

while(1)
{
if(xQueueReceive(&Q_OSTracing, &TraceMsg, portMAX_DELAY) == pdPASS)
{
if(TraceMsg.DateFlag)
{
_OS_Trace_GetTime(&TraceTime);
_OS_Trace_FormatTime(&TraceTime, &TraceMsg);
}

_OS_Trace_LogTrace(&TraceMsg);
}
}
}

vTaskDelayMs() is a macro that calls vTaskDelay and converts parameter in ms to ticks with portTICK_RATE_MS.

I'm curious why you test

if((ErrorCode.Code&ERRCODEMASK) == CODE_000_NO_ERROR)

when ErrorCode is a local variable and just been initialised so can't hold any value other than 0, but that is probably not relevant.

What is probably relevant is the following call:

if(xQueueReceive(&Q_OSTracing, &TraceMsg, portMAX_DELAY) == pdPASS)

You don't show the definition of Q_OSTracing, but I suspect you don't need the '&' in front of it.

If you declare it as:

xQueueHandle Q_OSTracing;

...and it the queue has been created, then you can read from it using:

xQueueReceive(Q_OSTracing, &TraceMsg, portMAX_DELAY);

As you are using portMAX_DELAY, you only need to test the return value if INCLUDE_vTaskSuspend is not set to 1 in FreeRTOSConfig.h. That is because if INCLUDE_vTaskSuspend is set to one portMAX_DELAY will act as an indefinite wait.

Regards.

“when ErrorCode is a local variable and just been initialised so can't hold any value other than 0, but that is probably not relevant.”

Yes it is, actually it's more a "way" that I try to respect, I agree this test isn't usefull ;)

“What is probably relevant is the following call: [...] You don't show the definition of Q_OSTracing, but I suspect you don't need the '&' in front of it. If you declare it as:
xQueueHandle Q_OSTracing;”

Exact ! I'm more familiar with EmbOS from Segger, in which queue type is a structure, not a handle, which is actually just a void pointer ... I made the same mistake when I wanted to put a message into the queue :

if(xQueueIsQueueFullFromISR(Q_OSTracing) != pdFALSE)
{
xQueueSend(&Q_OSTracing, &TraceMsg, MS_TO_TICK(50));
}

That's why I got troubles in sending messages too.

“As you are using portMAX_DELAY, you only need to test the return value if INCLUDE_vTaskSuspend is not set to 1 in FreeRTOSConfig.h. That is because if INCLUDE_vTaskSuspend is set to one portMAX_DELAY will act as an indefinite wait.”

Yes, my task is suspended. I will let the test because this task maybe be used with different configuration of FreeRTOS, it is some kind of generic method to trace OS and application events for a few different FreeRTOS based softwares.

Anyway, thank you for your help !