Hi Last week I started porting Helix mp3 decoder to FreeRTOS enviroment and I stuck on DMA1Stream7IRQHandler. Inside the interrupr routine I release transmission complete semaphore by xSemaphoreGiveFromISR (xSemaphoreTC, &xHigherPriorityTaskWoken). Calling of this function causes permanent stuck inside vPortValidateInterruptPriority( void ). I know the problem is related to the priorities, but i can't solve it by myself. Is there any helping hand? By the way, i'm rookie to FreeRTOS. :)

Dma configuration code ~~~ void DMA1Stream7cfg () { DMAInitTypeDef DMAInitStructure; NVICInitTypeDef NVICInitStructure;

RCC_AHB1PeriphClockCmd (RCC_AHB1Periph_DMA1, ENABLE);

DMA_DeInit (DMA1_Stream7);
DMA_InitStructure.DMA_Channel = DMA_Channel_0;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) & SPI3->DR;
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;

DMA_InitStructure.DMA_Memory0BaseAddr = 0;
DMA_InitStructure.DMA_BufferSize = 0;

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_Low;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init (DMA1_Stream7, &DMA_InitStructure);

/* Config the DMA Stream IRQ Channel */
NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream7_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configMAX_SYSCALL_INTERRUPT_PRIORITY;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init (&NVIC_InitStructure);
/* Enable DMA request after last transfer (Single-ADC mode) */
DMA_ITConfig (DMA1_Stream7, DMA_IT_TC, ENABLE);
NVIC_EnableIRQ (DMA1_Stream7_IRQn);

} ~~~

DMA Irq ~~~ void DMA1Stream7IRQHandler () { BaseType_t xHigherPriorityTaskWoken; xHigherPriorityTaskWoken = pdFALSE;

if (DMA_GetITStatus (DMA1_Stream7,DMA_IT_TCIF7) != RESET)
{
	DMA_ClearITPendingBit (DMA1_Stream7, DMA_IT_TCIF7);
   /* and after that kernel hangs in vPortValidateInterruptPriority( void ) */
    xSemaphoreGiveFromISR (xSemaphoreTC, &xHigherPriorityTaskWoken);
	wait = 0;
}
portYIELD_FROM_ISR (xHigherPriorityTaskWoken);

} ~~~

and code fired transmission

~~~ if (buffready) { DMA1Stream7->NDTR = bufflen; DMA1Stream7->M0AR = (uint32t) buff; DMA1Stream7->CR |= DMASxCREN; buff_nr ^= 1;

			while (xSemaphoreTake (xSemaphoreTC, (TickType_t) 20) == pdFALSE)
			{
				vTaskDelay(1);
			}

~~~

Regards Krzysztof Sroka

I suspect your problem will be with this line:

NVICInitStructure.NVICIRQChannelPreemptionPriority = configMAXSYSCALLINTERRUPT_PRIORITY;

which is using an unshifted priority value (the priority bits are already set in the most significant bits) - whereas you probably need to use an unshifted value (whereas the priority bits are set in the least significant bits). See the following link for more details:

http://www.freertos.org/RTOS-Cortex-M3-M4.html

DMA1Stream7IRQHandler

In this handler it would be more efficient to use a direct to task notification than a semaphore.

So that any use of NVIC_Init () will cause mess up with priorities?

Regards Krzysztof Sroka

I'm not sure what more I can say over what I already mentioned in my last email as I have already pointed out the line in your code that I think is wrong. Perhaps you should grep NVIC_InitTypeDef in the FreeRTOS/demo directory to see examples of how the structure is being used (be careful to see how the FreeRTOS code is actually using it, rather than uses within the ST code itself).

Heh, the most confusing thing is that I have the same mechanism used in my previus project. The diference is is only in peripherials, where data was transferred form ADC to ram buffer.

~~~ void DMA2Stream0IRQHandler (void) { BaseType_t xHigherPriorityTaskWoken;

xHigherPriorityTaskWoken = pdFALSE;

if (DMA_GetITStatus (DMA2_Stream0, DMA_IT_TCIF0))
{
	DMA_ClearITPendingBit (DMA2_Stream0, DMA_IT_TCIF0);
	TIM_Cmd (TIM2, DISABLE);
	xSemaphoreGiveFromISR (xSemaphore, &xHigherPriorityTaskWoken);
	GPIO_ToggleBits( GPIOD, GPIO_Pin_8);
}

if (DMA_GetITStatus(DMA2_Stream0, DMA_IT_TEIF0))
{
	DMA_ClearITPendingBit(DMA2_Stream0, DMA_IT_TEIF0);
	xSemaphoreGiveFromISR (xSemaphore, &xHigherPriorityTaskWoken);
}
portYIELD_FROM_ISR (xHigherPriorityTaskWoken);

} ~~~

and init

~~~ NVICInitStructure.NVICIRQChannel = DMA2Stream0IRQn; NVICInitStructure.NVICIRQChannelPreemptionPriority = 13; NVICInitStructure.NVICIRQChannelSubPriority = 13; NVICInitStructure.NVICIRQChannelCmd = ENABLE; NVICInit (&NVICInitStructure); ~~~

Code above works perfectly. Weird...

Regards Krzysztof Sroka

I have tested now pri and subpri set to 13. Nothing changes.

Regards Krzysztof Sroka

I have tested now pri and subpri set to 13. Nothing changes.

Please read the page I linked to in my first reply, and look at the examples in the download. This is still wrong.

Mea culpa... I had incorrectly defined parameters configKERNELINTERRUPTPRIORITY and configMAXSYSCALLINTERRUPT_PRIORITY in FreeRTOSConfig.h. :/ Thank you very much for help! I'm tired of this and I read without understanding the content... Finally everything work ok.

Regards Krzysztof Sroka