DMA complete ISR -> mailbox post -> SV#8 Topic is solved

[elagil]

I see, that is good to know.

Everything works if the DMA ISR does not send any event but breaks otherwise. The event listener has a stack size of 1024, all other threads (not doing much, really) mostly 256 or 1024.

[Giovanni]

I suggest to selectively disable parts of your application until you find the one that triggers the problem.

Giovanni

[elagil]

Switching off all other threads does not even help! Interesting.

Only tcp_sender is active, which receives the event.

Now, the stack trace is very short. After only 14 steps, it stops. I am bothered by VectorB0, is that an exception?

[Giovanni]

Vector B0 is an ISR.

Giovanni

[elagil]

I am not aware of creating it, is it doing something in particular? I also often see Vector120.

Adrian

[Giovanni]

Vector B0 is associated to an USART if I remember well, the list in on the STM32 Reference Manual.

Giovanni

[elagil]

Ok, thank you. I will have a look.

I have another question, though. I give the DMA a callback function to call on transfer complete. Do I have to treat it just like an ISR?

More specifically, do I need to put

CH_IRQ_PROLOGUE()

and

CH_IRQ_EPILOGUE()

inside the handler? I suppose that this is not an actual ISR but a callback called from the DMA ISR.

Thanks,
Adrian

[Giovanni]

Hi,

Callbacks must not use macros, just plain functions, macros must be placed only in ISR top level function.

Giovanni

[elagil]

Thanks, that seems to be it! It does not run into the exception handler anymore. Events work fine now, too.

One last question: The dmaStreamAllocate expects an IRQ priority MASK. However, there are no macros for DMA priority masks. I just give it the number "3". Is that ok? What range of numbers is allowed? I know that 0 and 1 shall not be used.

Thanks again,
Adrian

Here is the complete code for configuring input capture with DMA. I use this for capturing a parallel 16 bit external ADC input. The input capture unit triggers on the ADC sampling clock and requests the DMA to collect the input data from a chosen port (16 bit parallel input in my case).

First, the ICU configuration structure:
It also enables the request for the DMA in the timer. I use timer 1 channel 2 for DMA 2 stream 2.

Code: Select all

/**
 * Configuration structure for the input capture unit (ICU)
 */
ICUConfig icucfg = {
  ICU_INPUT_ACTIVE_HIGH,
  40000000,    /** 40 MHz ICU clock frequency.   */
  NULL,
  NULL,
  NULL,
  ICU_CHANNEL_2,
  /** DIER Register for enabling CH2 request on DMA */
  STM32_TIM_DIER_UDE | TIM_DIER_CC2DE
};


The following goes in my main() function and starts the ICU and DMA. It also contains the DMA config.
I use a circular DMA with two memory buffers between which the DMA switches each time. They are called mem0 and mem1.
ADC_SAMPLES is #define(d) to 1024 in my case

Code: Select all

/*****************************************************************************
   * Configure ICU and DMA for ADC capturing
   */

  /**
   * Start ICU (input capture unit) for DMA request generation
   *
   * The ADC clock signal is sampled by this ICU.
   */

  icuStart(&ICUD1, &icucfg);
  icuStartCapture(&ICUD1);

  /**
   * Allocate stream, dma_complete_handler is called in case of a complete
   * DMA transaction
   */
  dmaStreamAllocate(STM32_DMA2_STREAM2,
                    3,
                    (stm32_dmaisr_t)dma_complete_handler,
                    (void *)STM32_DMA2_STREAM2);

  /**
   * Set the DMA source address, GPIO port J
   */
  dmaStreamSetPeripheral(STM32_DMA2_STREAM2, &GPIOJ->IDR);

  /**
   * Set the DMA destination addresses. This can be configured as a double
   * buffer DMA, so two buffers are specified
   */
  dmaStreamSetMemory0( STM32_DMA2_STREAM2, mem0);
  dmaStreamSetMemory1( STM32_DMA2_STREAM2, mem1);

  /**
   * Size of one complete DMA transaction in samples of 16 bit
   */
  dmaStreamSetTransactionSize( STM32_DMA2_STREAM2, ADC_SAMPLES );

  /**
   * DMA configuration:
   * - Priority 0 (Very high 3..0 Low)
   * - Half word transfer size (16 bit)
   * - Circular DMA mode
   * - Direction: Peripheral to memory
   * - Increase memory pointer automatically
   * - Enable DMA transfer complete interrupt
   * - Select channel 6 (DMA 2, Stream 2, Tim1Ch2)
   * - Dual buffer mode, switches between two memories
   */
  dmaStreamSetMode( STM32_DMA2_STREAM2,
                    STM32_DMA_CR_PL(0) | STM32_DMA_CR_PSIZE_HWORD |
                    STM32_DMA_CR_MSIZE_HWORD | STM32_DMA_CR_DIR_P2M |
                    STM32_DMA_CR_MINC | STM32_DMA_CR_CIRC |
                    STM32_DMA_CR_CHSEL(6) | STM32_DMA_CR_TCIE |
                    STM32_DMA_CR_DBM );
  /**
   * enable the stream
   */

  dmaStreamEnable(STM32_DMA2_STREAM2);

  /**
   * End configure DMA
   ****************************************************************************/


This is the DMA transfer complete handler that is called on DMA complete interrupt:
It also sends some events to other parts of my application. Be sure to initialize the event source first if you want to use something similar.

Code: Select all

/**
 * Process DMA complete interrupt
 *
 * Detects, which memory was last filled with data. Starts processing and
 * transmission to host PC.
 *
 */
void dma_complete_handler(stm32_dma_stream_t * dmastp, uint32_t flags)
{
  (void) flags;

  /**
   * Current buffer is Memory 0
   */
  if((dmastp->stream->CR & DMA_SxCR_CT) == 0)
  {
    chSysLockFromISR();
    chEvtBroadcastFlagsI(&dma_event_source, DMA_MEM0_READY);
    chSysUnlockFromISR();
  }
  /**
   * Current buffer is Memory 1
   */
  else
  {
    chSysLockFromISR();
    chEvtBroadcastFlagsI(&dma_event_source, DMA_MEM1_READY);
    chSysUnlockFromISR();
  }

  dmaStreamClearInterrupt(dmastp);
}


[Giovanni]

Hi,

That "mask" is a documentation leftover from an old version, valid values are 2..15.

Giovanni