dsPIC33F keeps crashing: stack error

anonymous wrote on Sunday, November 13, 2011:

I have modified the standard demo code for the PIC24F/dsPIC33F port. I just want to get a feel of how FreeRTOS works. I’m using the MPLAB simulator (no hardware yet.)

The basic program just launches the watchdog task and goes idle, waking up only every 500ms to serve the watchdog. It runs the task once, but then crashes. I plan to add a few more tasks later but I thought I’d start off small.

My code for main.c is below (the rest of the code in the demo is unmodified):

/* Standard includes. */
#include <stdio.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "croutine.h"
/* Application includes. */
#include "BlockQ.h"
#include "crflash.h"
#include "blocktim.h"
#include "integer.h"
#include "comtest2.h"
#include "partest.h"
#include "lcd.h"
#include "timertest.h"
#include "portmacro.h"
void pre_RTOS_init_hardware()
	// e.g. setup CPU clock/PLL
	// setup analog inputs
	// setup uart config
	// etc.
 * Watchdog task. This periodically runs (at least once a second) to 
 * clear the watchdog. The watchdog will reset the processor if more
 * than one second elapses between watchdog events. The watchdog has
 * a very high priority level but it only executes every 500ms. 
void vWatchdogTask(void *pvParameters)
		// Here we would clear the WDT (TODO.)
		vTaskDelay(500 / portTICK_RATE_MS); 
 * Idle hook. This doesn't execute anything.
 * TODO: Low power mode.
void vApplicationIdleHook()
int main()
    // Set up the hardware (before the RTOS scheduler starts.)
    // Create the watchdog task. This periodically clears the WDT.
    xTaskCreate(vWatchdogTask, (signed char*) "Watchdog", 16, NULL, 0, NULL );
    // Start the scheduler. This function should not return as it causes the execution
    // context to change from main() to one of the created tasks. 
    // Should never get here.
    return 0;

The crash:

CORE-E0002: Trap due to misaligned data word access, occurred from instruction at 0x001de8
CORE-E0003: Trap due to unimplemented RAM memory access, occurred from instruction at 0x001de8
CORE-E0001: Trap due to stack error, occurred from instruction at 0x001de8
CORE-W0008: Software Reset Instruction called at PC=0x0002be

I’m sure I must have missed something out but I can’t think what it is. If more info is needed please let me know.


rtel wrote on Sunday, November 13, 2011:

You have only allocated 16 words of stack.  You need to allocate at least configMINIMAL_STACK_SIZE bytes (taking the value form the original demo), more if you task does anything other than calling a few self defined functions that don’t use much stack.

I would also suggest taking the call to the co routine schedule out unless you have co-routines too.


anonymous wrote on Sunday, November 13, 2011:

Thanks Richard, that solved the problem.