PIC33: Problem with taskschedule

patricknew wrote on Monday, January 19, 2015:

hi everyone,
this is my first time working with FreeRTOS and i hope u guys could help me.

First:
I´m using MPLABv8.30 and the C30v3.12 compiler. I´m working with the dsPIC33FJ256GP710 uC and the Microchip PICkit2 Programmer.

I´m using the FreeRTOS demo project (.\FreeRTOSV8.1.2\FreeRTOS\Demo\dsPIC_MPLAB).

Problem:
I was just playing with tasks but the tasks arent context switching - Programm remains in the first created task.

Configuration:

//default values of the demo project
#define configUSE_PREEMPTION	        1
#define configUSE_TIME_SLICING 	        1 
#define configUSE_IDLE_HOOK			1
#define configUSE_TICK_HOOK			0
#define configTICK_RATE_HZ			( ( TickType_t ) 1000 )
#define configCPU_CLOCK_HZ			( ( unsigned long ) 25000000 )  /* Fosc / 2 */
#define configMAX_PRIORITIES		( 4 )
#define configMINIMAL_STACK_SIZE		( 105 )
#define configTOTAL_HEAP_SIZE		( ( size_t ) 5120 )
#define configMAX_TASK_NAME_LEN		( 4 )
#define configUSE_TRACE_FACILITY		0
#define configUSE_16_BIT_TICKS		1
#define configIDLE_SHOULD_YIELD		1

main:

//both tasks with same priority
xTaskCreate(first_task,"f", 1024, NULL, 1, NULL);
xTaskCreate(secound_task,"s", 1024, NULL, 1, NULL);
vTaskStartScheduler();

tasks:

void first_task(void *p){
	while(1){
		function_one();
	}
}



void secound_task(void *p){
	while(1){
		function_two();
	}
}

tick Interrupt:

void __attribute__((__interrupt__, auto_psv)) configTICK_INTERRUPT_HANDLER( void )
{
	/* Clear the timer interrupt. */
	IFS0bits.T1IF = 0;

	if( xTaskIncrementTick() != pdFALSE )
	{
		portYIELD();
	}
}

The tick-Interrupt occurs but the function “xTaskIncrementTick()” returns always pdFALSE - I never reach “portYIELD()”.

I really dont know why this is happening but I hope someone out there knows whats wrong.

rtel wrote on Monday, January 19, 2015:

Is the tick interrupt executing? Try putting a break point in it, or
viewing the tick count (xTickCount) in the debugger.

If you add taskYIELD() calls into the tasks, do they switch between each
other then?

void first_task(void *p){
while(1){
function_one();
taskYIELD();
}
}

I’m assuming function_one() and function_two() are not doing anything
that may cause a problem?

patricknew wrote on Monday, January 19, 2015:

Hello,

  • I tried to use the taskYIELD() but it didnt worked.

  • function_one() and function_two() are putting some strings on the LCD-Display. The display shows the text from function_one(). If I put a break point in function_two() the debugger doesnt reach it.
    If I create the second_task before the first_task then the text from function_two() is shown on the display - function_one() doesnt execute.

  • tick interrupt is executing. Tomorrow I will view the tick count (xTickCount).

  • I should add that I removed most of the demo tasks because I thought that I wont need them. I havent touched the header files but I removed the following source files:

ParTest.c, timertest.c, BlockQ.c, blocktim.c, comtest.c, crflash.c and integer.c

My whole main-function:
LCD, LED and the buttons are working perfectly fine.

int main(void) {
	// Init
	config_osc();
	Init_LCD();
	Init_LED();
	Init_Buttons();
	Init_ADC();

    xTaskCreate(first_task,"f", 1024, NULL, 1, NULL);
    xTaskCreate(secound_task,"s", 1024, NULL, 1, NULL);
    vTaskStartScheduler();

return 0;
}

rtel wrote on Monday, January 19, 2015:

I tried to use the taskYIELD() but it didnt worked.

So neither the tick interrupt or a yield is causing a task switch. Are
you sure both tasks were created? Did you check the return value of
xTaskCreate(), as your stack sizes are very big and it might just be
that only one task is ever created.

function_one() and function_two() are putting some strings on the
LCD-Display. The display shows the text from function_one(). If I
put a break point in function_two() the debugger doesnt reach it.
If I create the second_task before the first_task then the text from
function_two() is shown on the display - function_one() doesnt execute.

Try replacing the call to function_one and function_two with a simple
variable increment. For example, define the two variables:

volatile uint32_t ul1 = 0, ul2 = 0;

Then replace the call to function_one() with ul1++, and replace the call
to function_two() with ul2++. Leave the call to taskYIELD() in there
too. You should be able to simple step through the taskYIELD() code
then to see what happens.

I should add that I removed most of the demo tasks because I thought
that I wont need them. I havent touched the header files but I
removed the following source files:

Probably best to also set configUSE_IDLE_HOOK to 0 as well as that demo
schedules co-routines in the idle hook.

Regards.

tlafleur wrote on Monday, January 19, 2015:

I use dsPIC33F processor with FreeRTOS and they work very well…

  1. I would suggest that you start with the supported demo… if your using
    an explorer 16 board, it will just run
    if your using your own hardware, make change for the LED and serial
    port in the standard demo…
    The standard demo is a good test to make sure your hardware is
    stable…

  2. If you can, move up to MPLABX and the XC compiler… and FreeRTOS 8.xx
    as a starting base

  3. add the FreeRTOS callback functions to see if your having a stack or
    memory issue…
    ( you will also need to enable them in FreeRTOSConfig.h)

  4. what FreeRTOS heap are you using heap_1.c, 2, 3 or 4??

  5. change your FreeRTOS task size to a bigger value by 2X or 3X

/* *********** FreeRTOS callback functions *********** */

/*


  • vApplicationIdleHook

*/

void vApplicationIdleHook( void )
{
/* Schedule the co-routines from within the idle task hook. */

}

/*


  • vApplicationTickHook

*/

void vApplicationTickHook( void )
{
/* This function will be called by each tick interrupt if
configUSE_TICK_HOOK is set to 1 in FreeRTOSConfig.h. User code can be
added here, but the tick hook is called from an interrupt context, so
code must not attempt to block, and only the interrupt safe FreeRTOS API
functions can be used (those that end in FromISR()). */

}

/*


  • vApplicationStackOverflowHook

*/

void vApplicationStackOverflowHook( xTaskHandle *pxTask, signed portCHAR
*pcTaskName )
{
taskDISABLE_INTERRUPTS();

while(1) ;             // we will hang here if we have stack overflow

}

/*


  • vApplicationMallocFailedHook

*/

void vApplicationMallocFailedHook( void )
{
/* vApplicationMallocFailedHook() will only be called if
configUSE_MALLOC_FAILED_HOOK is set to 1 in FreeRTOSConfig.h. It is a
hook
function that will get called if a call to pvPortMalloc() fails.
pvPortMalloc() is called internally by the kernel whenever a task,
queue,
timer or semaphore is created. It is also called by various parts of
the
demo application. If heap_1.c or heap_2.c are used, then the size of
the
heap available to pvPortMalloc() is defined by configTOTAL_HEAP_SIZE in
FreeRTOSConfig.h, and the xPortGetFreeHeapSize() API function can be
used
to query the size of free heap space that remains (although it does not
provide information on how the remaining heap might be fragmented). */

taskDISABLE_INTERRUPTS();


while(1) ;                     // we will hang here if we have stack

overflow
}

On Mon, Jan 19, 2015 at 10:00 AM, Patrick patricknew@users.sf.net wrote:

hi everyone,
this is my first time working with FreeRTOS and i hope u guys could help
me.

First:
I´m using MPLABv8.30 and the C30v3.12 compiler. I´m working with the
dsPIC33FJ256GP710 uC and the Microchip PICkit2 Programmer.

I´m using the FreeRTOS demo project
(.\FreeRTOSV8.1.2\FreeRTOS\Demo\dsPIC_MPLAB).

Problem:
I was just playing with tasks but the tasks arent context switching -
Programm remains in the first created task.

Configuration:

//default values of the demo project#define configUSE_PREEMPTION 1#define configUSE_TIME_SLICING 1 #define configUSE_IDLE_HOOK 1#define configUSE_TICK_HOOK 0#define configTICK_RATE_HZ ( ( TickType_t ) 1000 )#define configCPU_CLOCK_HZ ( ( unsigned long ) 25000000 ) /* Fosc / 2 */#define configMAX_PRIORITIES ( 4 )#define configMINIMAL_STACK_SIZE ( 105 )#define configTOTAL_HEAP_SIZE ( ( size_t ) 5120 )#define configMAX_TASK_NAME_LEN ( 4 )#define configUSE_TRACE_FACILITY 0#define configUSE_16_BIT_TICKS 1#define configIDLE_SHOULD_YIELD 1

main:

//both tasks with same priorityxTaskCreate(first_task,“f”, 1024, NULL, 1, NULL);xTaskCreate(secound_task,“s”, 1024, NULL, 1, NULL);vTaskStartScheduler();

tasks:

void first_task(void *p){
while(1){
function_one();
}}
void secound_task(void *p){
while(1){
function_two();
}}

tick Interrupt:

void attribute((interrupt, auto_psv)) configTICK_INTERRUPT_HANDLER( void ){
/* Clear the timer interrupt. */
IFS0bits.T1IF = 0;

if( xTaskIncrementTick() != pdFALSE )
{
    portYIELD();
}}

The tick-Interrupt occurs but the function “xTaskIncrementTick()” returns
always pdFALSE - I never reach “portYIELD()”.

I really dont know why this is happening but I hope someone out there
knows whats wrong.

PIC33: Problem with taskschedule
https://sourceforge.net/p/freertos/discussion/382005/thread/4ff5d22b/?limit=25#6e48

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Tom Lafleur

patricknew wrote on Tuesday, January 20, 2015:

Hi,
after I did some stack and memory managment everything is wokring fine.

Thanks for helping!