SPI Communication Problems Concerning nRF52840

[June6]

Now there is a project, nrf52840 uses SPI to communicate with other microcontrollers. Data is currently available, but it is suspected that each packet lacks a second byte. The corresponding modification of SPI mode eliminates the problem of SPI mode. Are there any other parameters that affect the results of the data?

SPI Communication Program Reference Sample Program （sdk15.0    examples\peripheral\spi\pca10040）

[Edvin]

Can you try to analyze the SPI MOSI and MISO lines to see if you are actually missing any data?

[June6]

#define TEST_STRING "Nordic 1234567890123"
static uint8_t       m_tx_buf[] = TEST_STRING;           /**< TX buffer. */
static uint8_t       m_rx_buf[sizeof(TEST_STRING) + 1];    /**< RX buffer. */
static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */

static volatile bool spis_xfer_done; /**< Flag used to indicate that SPIS instance completed the transfer. */

void spis_event_handler(nrf_drv_spis_event_t event)
{
    static uint8_t MyString[DATA_BUFFER_SIZE];
    static uint8_t MyStringIndex = 0;
    int i, j;
    uint8_t *StartPointer, *NextPointer;
    if (event.evt_type == NRF_DRV_SPIS_XFER_DONE)
    {
        spis_xfer_done = true;
        if (MyStringIndex == DATA_BUFFER_SIZE)
         {
//            NRF_LOG_INFO(" Transfer completed. Received: %d\n", MyStringIndex);

            //Find the first Data
            for (i = 0; i < DATA_BUFFER_SIZE; i ++)
              if (MyString[i] == 0x80 || MyString[i] == 0x90 || MyString[i] == 0xa0)
              break;

            if (i < DATA_BUFFER_SIZE)
            {
              StartPointer = &MyString[i]; 

            while ((StartPointer != NULL) && (StartPointer < (&MyString[DATA_BUFFER_SIZE - 1])) && (StartPointer + 16 < (&MyString[DATA_BUFFER_SIZE - 1])) )
            {
              NextPointer = StartPointer + 1;
              //Find the ending of the data
              for (j = 1; j < 16; j ++, NextPointer ++)
              {
                if (*NextPointer == 0x80 || *NextPointer == 0x90 || *NextPointer == 0xa0)
                break;
              }

              //Show the data to RTT or UART
              NRF_LOG_HEXDUMP_INFO(StartPointer, j);
              StartPointer += j;
            }

            memset(MyString, 0, 100);
            MyStringIndex = 0;
          }
         }
         MyString[MyStringIndex] = m_rx_buf[0];
         MyStringIndex ++;
  }
}

int main(void)
{
    // Enable the constant latency sub power mode to minimize the time it takes
    // for the SPIS peripheral to become active after the CSN line is asserted
    // (when the CPU is in sleep mode).
    NRF_POWER->TASKS_CONSTLAT = 1;

    bsp_board_init(BSP_INIT_LEDS);
 
    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_DEFAULT_BACKENDS_INIT();

    NRF_LOG_INFO("SPIS example");

    nrf_drv_spis_config_t spis_config = NRF_DRV_SPIS_DEFAULT_CONFIG;
    spis_config.mode = NRF_SPIS_MODE_1;
    spis_config.csn_pin               = APP_SPIS_CS_PIN;
    spis_config.miso_pin              = APP_SPIS_MISO_PIN;
    spis_config.mosi_pin              = APP_SPIS_MOSI_PIN;
    spis_config.sck_pin               = APP_SPIS_SCK_PIN;


    APP_ERROR_CHECK(nrf_drv_spis_init(&spis, &spis_config, spis_event_handler));

    while (1)
    {
        spis_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spis_buffers_set(&spis, m_tx_buf, 0, m_rx_buf, 20));

        while (!spis_xfer_done)
        {
            __WFE();
        }

        NRF_LOG_FLUSH();

//        bsp_board_led_invert(BSP_BOARD_LED_0);
    }
}