CC3200 SPI Slave bad receive

Question

Solved: I had to handle CS/NSS pin for slave. Add some delay before and after TX.

void SlaveMain()
{
    MAP_SPIReset(GSPI_BASE);

    MAP_SPIConfigSetExpClk(GSPI_BASE,MAP_PRCMPeripheralClockGet(PRCM_GSPI),
                     SPI_IF_BIT_RATE,SPI_MODE_SLAVE,SPI_SUB_MODE_0,
                     (SPI_SW_CTRL_CS |
                     SPI_4PIN_MODE |
                     SPI_TURBO_OFF |
                     SPI_CS_ACTIVELOW |
                     SPI_WL_8));

    MAP_SPIEnable(GSPI_BASE);
}

while(1)
{
    MAP_SPICSEnable(GSPI_BASE);
    MAP_SPIDataGet(GSPI_BASE, &data);
    Report("Got: %d\n\r", data);
    MAP_SPICSDisable(GSPI_BASE);
}

My problem is that I receive wrong data from STM32F4 board via SPI. My CC3200 board SPI slave config:

#define SPI_IF_BIT_RATE  100000
void SlaveMain()
{
    // Set Tx buffer index
   ucTxBuffNdx = 0;
   ucRxBuffNdx = 0;

   // Reset SPI
   MAP_SPIReset(GSPI_BASE);

   // Configure SPI interface
   MAP_SPIConfigSetExpClk(GSPI_BASE,MAP_PRCMPeripheralClockGet(PRCM_GSPI),
                 SPI_IF_BIT_RATE,SPI_MODE_SLAVE,SPI_SUB_MODE_0,
                 (SPI_SW_CTRL_CS |
                 SPI_4PIN_MODE |
                 SPI_TURBO_OFF |
                 SPI_CS_ACTIVEHIGH |
                 SPI_WL_8));

   // Register Interrupt Handler
   MAP_SPIIntRegister(GSPI_BASE,SlaveIntHandler);

   // Enable Interrupts
   MAP_SPIIntEnable(GSPI_BASE,SPI_INT_RX_FULL|SPI_INT_TX_EMPTY);

   // Enable SPI for communication
   MAP_SPIEnable(GSPI_BASE);

   Message("Enabled SPI Interface in Slave Mode\n\rReceived : ");
}

Interrupt:

static void SlaveIntHandler()
{
    unsigned long ulRecvData;
    unsigned long ulStatus;

    ulStatus = MAP_SPIIntStatus(GSPI_BASE,true);

    MAP_SPIIntClear(SSPI_BASE,SPI_INT_RX_FULL|SPI_INT_TX_EMPTY);

    if(ulStatus & SPI_INT_RX_FULL)
    {
    MAP_SPIDataGetNonBlocking(GSPI_BASE,&ulRecvData);
    Report("Received: %d\n\r",ulRecvData);
    }
}

And my STM32F4 board config for SPI Master:

void MX_SPI2_Init(void)
{
  hspi2.Instance = SPI2;
  hspi2.Init.Mode = SPI_MODE_MASTER;
  hspi2.Init.Direction = SPI_DIRECTION_2LINES;
  hspi2.Init.DataSize = SPI_DATASIZE_8BIT;
  hspi2.Init.CLKPolarity = SPI_POLARITY_LOW;
  hspi2.Init.CLKPhase = SPI_PHASE_1EDGE;
  hspi2.Init.NSS = SPI_NSS_SOFT;
  hspi2.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_16;
  hspi2.Init.FirstBit = SPI_FIRSTBIT_MSB;
  hspi2.Init.TIMode = SPI_TIMODE_DISABLE;
  hspi2.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
  hspi2.Init.CRCPolynomial = 10;
  HAL_SPI_Init(&hspi2);
}

  uint8_t data;

  while (1)
  {
    HAL_Delay(500);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, GPIO_PIN_RESET);
    data = 6;
    HAL_SPI_Transmit(&hspi2, &data, 1, 50);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, GPIO_PIN_SET);
    HAL_Delay(500);
  }

Result I get from CC3200 and it changes after I reset Master device:

Where could be a problem?

Answer 1

I'm assuming HAL_GPIO_WritePin is your chip select line. Since SPI transmits data serially, it is possible that you set the GPIO (and disable SPI communication) before all the bits have been sent (especially since the SPI clock is usually only around ~4MHz). Check/post the code in the HAL_SPI_Transmit function and see if it checks for some kind of SPI ready bit before returning. For debugging purposes, try adding some delay prior to each HAL_GPIO_WritePin call. Also, check the bit length of the SPI register. You may have configured it for 8-bit transmissions, but if the register is actually 16 or 32 bit, then the transmitted data might need to be left-justified before writing (e.g. 0xFF becomes 0xFF00 if transmitting 8-bit data on a 16-bit SPI register).

Answer 2

(Slave is configured to SW controlled CS/NSS pin, and you currently do not handle that). SPI usually uses CS pin to resync, so if one bit is lost in your transmission, or the slave starts up after master has started to transmit), it will currently never recover (SPI has no START/STOP bits).