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Original question:

MSP432P401R: DMA External Trigger by external ADC data ready -> SPI Starts

MSP432P401R: External DMAE0 Trigger SPI

Michael Liesenberg85
Mastermind 7560 points

Part Number: MSP432P401R

Hi,

i am trying to get external DMA trigger to work with an external ADC (ADS131A02).

I am receiving the INT from ADS131A02 but DMA is not getting triggert. 

Is there anything wrong with my code:

#define SAMPLE_LENGTH 512
int32_t data_array1[SAMPLE_LENGTH];
int32_t data_array2[SAMPLE_LENGTH];
uint8_t data_array[4]={0x00,0x00,0x00,0x00};
volatile int switch_data = 0;

void ADS131A02_DMASetup(void)
{

    //Assigning DMA to SPI Channels
    DMA_enableModule();
    DMA_setControlBase(controlTable);


    DMA_assignChannel(DMA_CH0_EUSCIB0TX0);
    DMA_assignChannel(DMA_CH1_EUSCIB0RX0);
    DMA_assignChannel(DMA_CH6_EXTERNALPIN);

    DMA_disableChannelAttribute(DMA_CH6_EXTERNALPIN,UDMA_ATTR_ALTSELECT | UDMA_ATTR_USEBURST |UDMA_ATTR_HIGH_PRIORITY |UDMA_ATTR_REQMASK);

    // Setup the TX transfer characteristics & buffers
    DMA_setChannelControl( DMA_CH6_EXTERNALPIN | UDMA_PRI_SELECT,UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1);
    DMA_setChannelTransfer(DMA_CH6_EXTERNALPIN | UDMA_PRI_SELECT,UDMA_MODE_BASIC, data_array,(void *) MAP_SPI_getTransmitBufferAddressForDMA(EUSCI_B0_BASE), 4);

    DMA_setChannelControl (DMA_CH0_EUSCIB0TX0 | UDMA_PRI_SELECT,UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1);
    DMA_setChannelTransfer(DMA_CH0_EUSCIB0TX0 | UDMA_PRI_SELECT,UDMA_MODE_BASIC, data_array,(void *) MAP_SPI_getTransmitBufferAddressForDMA(EUSCI_B0_BASE),3);

    DMA_setChannelControl (DMA_CH1_EUSCIB0RX0 | UDMA_PRI_SELECT,UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1);
    DMA_setChannelTransfer(DMA_CH1_EUSCIB0RX0 | UDMA_PRI_SELECT,UDMA_MODE_PINGPONG,(void *) MAP_SPI_getReceiveBufferAddressForDMA(EUSCI_B0_BASE),data_array1,SAMPLE_LENGTH);

    DMA_setChannelControl (DMA_CH1_EUSCIB0RX0 | UDMA_PRI_SELECT,UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1);
    DMA_setChannelTransfer(DMA_CH1_EUSCIB0RX0 | UDMA_PRI_SELECT,UDMA_MODE_PINGPONG,(void *) MAP_SPI_getReceiveBufferAddressForDMA(EUSCI_B0_BASE),data_array2,SAMPLE_LENGTH);

    DMA_assignInterrupt(DMA_INT1, 6);
    DMA_clearInterruptFlag(INT_DMA_INT1);
    DMA_clearInterruptFlag(6);

    Interrupt_enableInterrupt(DMA_INT1);
    Interrupt_enableMaster();
    DMA_enableChannel(6);
    DMA_enableChannel(0);
    DMA_enableChannel(1);
}

And here is my DMA INT:

void DMA_INT1_IRQHandler(void)
{
    DMA_clearInterruptFlag(6);
    /* Switch between primary and alternate bufferes with DMA's PingPong mode */
    if (DMA_getChannelAttribute(6) & UDMA_ATTR_ALTSELECT)
    {
        DMA_setChannelControl(UDMA_PRI_SELECT  | DMA_CH1_EUSCIB0RX0,UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1);
        DMA_setChannelTransfer(UDMA_PRI_SELECT | DMA_CH1_EUSCIB0RX0,UDMA_MODE_PINGPONG, (void*)MAP_SPI_getReceiveBufferAddressForDMA(EUSCI_B0_BASE),data_array1, SAMPLE_LENGTH);
        switch_data = 1;
    }
    else
    {
        DMA_setChannelControl(UDMA_ALT_SELECT | DMA_CH1_EUSCIB0RX0,UDMA_SIZE_32 | UDMA_SRC_INC_NONE | UDMA_DST_INC_32 | UDMA_ARB_1);
        DMA_setChannelTransfer(UDMA_ALT_SELECT | DMA_CH1_EUSCIB0RX0,UDMA_MODE_PINGPONG, (void*)MAP_SPI_getReceiveBufferAddressForDMA(EUSCI_B0_BASE),data_array2, SAMPLE_LENGTH);
        switch_data = 0;
    }
}

  • 0
    TI__Mastermind 22580 points
    Hello Michael,

    Looking at the code it seems you want to communicate with the External ADC using SPI and having trouble configuring SPI over DMA. If this understanding is correct, did you refer the example in the SimpleLink MSP432P4 SDK in the folder: ./simplelink_msp432p4_sdk_2_20_00_12/examples/nortos/MSP_EXP432P401R/driverlib?

    There are two example that use SPI with DMA - "dma_eusci_spi_loopback" and "dma_eusci_spi_scatter_gather".

    Thanks,
    Sai
  • 0 in reply to Sai Reddy
    Mastermind 7560 points

    Hi Sai,

    i know this examples and i already have SPI with DMA working with an other project.

    What i am not so sure, is adding the DMAE0 External PIN to trigger DMA.

    Is there any example of this?

  • 0 in reply to Michael Liesenberg85
    Mastermind 7560 points
    Hi Sai,

    i have the BOOSTXL-EDUMKII_MicrophoneFFT_MSP432P401R example that uses the internal 14Bit ADC which triggers with DMA_CH7_ADC14 the DMA directly too. This example works fine, also uses pingpong mode but i am not getting it the interrupt to work.
    Sending SPI stuf with DMA is the second step.
    First i have to make DMA_CH6_EXTERNALPIN to trigger an interrupt at DMA_INT1_IRQHandler.
  • 0 in reply to Michael Liesenberg85
    Guru 95535 points
    I don't see where you set P7.0 to be (alternate function) DMAE0 [ref SLAS826G Table 6-68.]
  • 0 in reply to Bruce McKenney
    Mastermind 7560 points

    Hi Bruce,
    what do you mean about alternate function? DMAE0 should only be an external PIN connectec to ADC INT. Once INT from ADC is fired, it will trigger the external DMAE0 (PIN 7.0) and this should handle the SPI transfer without needing to wake the CPU up.
    If the DMA receive buffer has like 512 values, it should fired the DMA_INT1_IR to wake the CPU after reading 512 values. Once CPU reads from the first buffer, the DMA keeps reading data and saving it to the second buffer. (PINGPONG)
    I have an example that this is working with the internal 14Bit ADC, but here it uses DMA_CH7_ADC14 to trigger the DMA.

    My problem is that DMA_INT1_IR gets never called. I change the buffer size to 1 Byte and hope to get DMA_INT1_IR fired but its not happening. I think DMA_CH6_EXTERNALPIN is not proper set on my code or something.
    Any idea?

  • 0 in reply to Michael Liesenberg85
    Guru 95535 points
    My idea is that you haven't set P7SELx properly to get the DMAE0 alternate function for P7.0. This is described in the MSP432P401R Data Sheet (SLAS826G, link at the top of the Product page) in Table 6-68 (p. 148).
  • 0 in reply to Bruce McKenney
    Mastermind 7560 points

    Hi Bruce,

    my configuration is correct i think:

    GPIO_setAsInputPinWithPullUpResistor(GPIO_PORT_P7, GPIO_PIN0);

GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P7, GPIO_PIN0, GPIO_PRIMARY_MODULE_FUNCTION);

    And here is the table:

    right? DMAE0 should only be an interrupt that trigger the DMA. Once DMA is done it will wake up the MCU and it will swap the arrays. Thats it.

  • 0 in reply to Michael Liesenberg85
    Guru 95535 points
    I didn't use driverlib, but that's how it worked when I did it.
  • 0 in reply to Bruce McKenney
    TI__Guru 57846 points
    Related thread and continued discussion can be found here:

    e2e.ti.com/.../704661

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