SPI Communication Problems Concerning nRF52840

RE: SPI Communication Problems Concerning nRF52840

Edvin — Tue, 08 Oct 2019 14:01:48 GMT

I assume that this is the same issue/question as in your other ticket?
https://devzone.nordicsemi.com/f/nordic-q-a/52719/spis-of-nrf52-could-not-read-the-data-accuracy

RE: SPI Communication Problems Concerning nRF52840

hzhuxin — Tue, 08 Oct 2019 10:39:41 GMT

Any solution avaliable?

RE: SPI Communication Problems Concerning nRF52840

hzhuxin — Mon, 23 Sep 2019 07:37:39 GMT

I am the colleague of June6, give more information for the problem.

We are using the SPIS sample in examples\peripheral\spis of15.3 SDK.
As show in the above Oscilloscope, the second bytes had sent after a long time after the first bytes(maybe 4.34 ms), and i read the rx_amount of nrf_drv_spis_event_t event in callback spis_event_handler, the value always is 1.
In this period, there are two bytes clk cycles(that mean clk has the 16 high low in turn) & two bytes appear there, and at the same time, the cs is low, so according the spi protocol, i should received two bytes, am i right?

After this period, the cs cycle changed to 500us, and in one cycle, there is a clk cycle(8 high low in turn), the interval is very short(maybe 30us), these data received perfect.

Please give us some suggestion on how to get the second bytes? how to modify the program?

RE: SPI Communication Problems Concerning nRF52840

June6 — Mon, 23 Sep 2019 06:44:57 GMT

The above engineering path is corrected to sdk15.3 examples\peripheral\spis\pca10040 (52832)

RE: SPI Communication Problems Concerning nRF52840

June6 — Sun, 22 Sep 2019 07:49:30 GMT

The normal chip selection cycle is 500us. However, the first chip selection cycle is 4.34ms.

RE: SPI Communication Problems Concerning nRF52840

June6 — Sun, 22 Sep 2019 07:22:31 GMT

The above is the waveform of data pin and chip selection pin.（The yellow waveform is the data pin waveform. The blue waveform is the chip selection pin waveform. And chip selection is pin low level effective）

Through the analysis of chip selection waveform and data, it is found that chip selection pin is always valid after the data transmission of the first byte, and invalid only after the data transmission of the second byte.Therefore, the data of the second byte is lost due to this problem.

RE: SPI Communication Problems Concerning nRF52840

Nguyen Hoan Hoang — Sat, 21 Sep 2019 16:34:45 GMT

Try this driver instead. it is much better and easier to use. it has been used in many projects and hundreds of devices, sensors, flash memory, sd card...

https://github.com/IOsonata/IOsonata/blob/master/ARM/Nordic/src/spi_nrf5x.cpp

usage example

https://github.com/IOsonata/IOsonata/blob/master/exemples/spi/spi_master_slave.cpp

RE: SPI Communication Problems Concerning nRF52840

June6 — Sat, 21 Sep 2019 14:40:14 GMT

#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);
    }
}

RE: SPI Communication Problems Concerning nRF52840

June6 — Sat, 21 Sep 2019 08:26:52 GMT

Can you test whether you will lose data when receiving data with SPI? The data received by SPI in my program is only 16 bytes, but the data transferred is actually 17 bytes. I lost the second byte data.

RE: SPI Communication Problems Concerning nRF52840

June6 — Sat, 21 Sep 2019 08:21:10 GMT

HI Edvin,Now it turns out that the second byte data is missing when receiving data.

RE: SPI Communication Problems Concerning nRF52840

June6 — Fri, 20 Sep 2019 17:09:12 GMT

All right. That's what I'm going to do. The day after tomorrow, I will connect the data source directly to the oscilloscope to monitor the data waveform, so that I can know where the problem is. Thank you for your reply.

RE: SPI Communication Problems Concerning nRF52840

Edvin — Fri, 20 Sep 2019 13:37:39 GMT

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

RE: SPI Communication Problems Concerning nRF52840

June6 — Fri, 20 Sep 2019 03:06:58 GMT

Hope to be helped.

Best wishes

June6