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[FreeRTOS Home] [Live FreeRTOS Forum] [FAQ] [Archive Top] [November 2009 Threads] using vTaskDelayUntil questionsPosted by Brian Carver on November 4, 2009 I am trying a simple delay into my simple program so I can control the rate of delay to flash an LED on/off. Here is the code:
int i; portTickType xLastWakeTime; const portTickType xFrequency = 10000;
LATBbits.LATB2 = 1;// Set LAT register to turn on LED xLastWakeTime = xTaskGetTickCount();
for(;;) { vTaskDelayUntil(&xLastWakeTime, xFrequency); //for(i=0; i<0xFFFF; i++); //for(i=0; i<0xFFFF; i++); //for(i=0; i<0xFFFF; i++); taskENTER_CRITICAL(); LATBbits.LATB3 = ~LATBbits.LATB3;// Set LAT register bit 3 to turn on LED taskEXIT_CRITICAL();
When I use the function vTaskDelayUntil the code does not work, but If I comment out my busy wait loops, those work well. I know the delayUntil function is a better way to go, as the processor might go to sleep in the idle task (hopefully a correct assumption)
I followed the debugger into the code, I can see the task get placed into the wait queue, but it's really hard to see when the task is released from the wait queue.
Any suggestion?
RE: using vTaskDelayUntil questionsPosted by MEdwards on November 4, 2009 Check the tick interrupt is running. If not then the task will never leave the delay.
10000 is potentially a long delay too, 10 seconds if the tick frequency is 1KHz, 100 seconds if the tick frequency is 100Hz.
RE: using vTaskDelayUntil questionsPosted by Brian Carver on November 4, 2009 You are correct, the tick interrupt is not running. I changed my code to this: xLastWakeTime = xTaskGetTickCount(); vTaskDelayUntil(&xLastWakeTime, xFrequency);
I set a debug break on the vTaskDelayUntil line to read the value xLastWakeTime. The value read zero every time, i looped through the application.
Thinking I had the right option I turned on
#define configUSE_TICK_HOOK1
That resulted into a compile error: Source\tasks.c:1362: undefined reference to `vApplicationTickHook'
I am using a PIC24F16KA102 for my chip. So I know the scheduler is started as I call vTaskStartScheduler(); and that starts the task interrupt.
The suggestion was spot on, but I really don't know how to make sure the tick interrupt is really working.
RE: using vTaskDelayUntil questionsPosted by Brian Carver on November 5, 2009 I really now know that the scheduler is giving control to my function but the interrupt tick is not working. I added an extra task to send a character on the UART. The uartTask and my ledTask (flasher) does not work together. At least I am not seeing a context switch between the two. So I have a configuration issue with my code, any more suggestions?
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