SPI master problem

[amitash]

Hi,

I am using nrf52833 EVB as an SPI master. The data is sent properly and well-received at the slave, however, I have a problem with the data received.

The problem is that every second transaction I get the wrong data. For example if the slave is sending a growing counter the data received will look like this:

0, 128, 2, 128, 4, 0, 128 .......

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#include "nrf_drv_spi.h"

#include "app_util_platform.h"

#include "nrf_gpio.h"

#include "nrf_delay.h"

#include "boards.h"

#include "app_error.h"

#include <string.h>

#include "nrf_log.h"

#include "nrf_log_ctrl.h"

#include "nrf_log_default_backends.h"

#include "nrf_gpio.h"

#define SPI_INSTANCE 0 /**< SPI instance index. */

static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE); /**< SPI instance. */

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

#define TEST_STRING "Nordic"

static uint8_t m_tx_buf[] = {0xFF}; /**< TX buffer. */

static uint8_t m_rx_buf[1]; /**< RX buffer. */

static const uint8_t m_length = sizeof(m_tx_buf); /**< Transfer length. */

int counter = 0;

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

#include "nrf_drv_spi.h"
#include "app_util_platform.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "boards.h"
#include "app_error.h"
#include <string.h>
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "nrf_gpio.h"

#define SPI_INSTANCE  0 /**< SPI instance index. */
static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE);  /**< SPI instance. */
static volatile bool spi_xfer_done;  /**< Flag used to indicate that SPI instance completed the transfer. */

#define TEST_STRING "Nordic"
static uint8_t       m_tx_buf[] = {0xFF};           /**< TX buffer. */
static uint8_t       m_rx_buf[1];    /**< RX buffer. */
static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */
int counter = 0;
uint8_t commands[] = {0,1,0,2,0,3};
/**
 * @brief SPI user event handler.
 * @param event
 */

void spi_event_handler(nrf_drv_spi_evt_t const * p_event,
                       void *                    p_context)
{
    spi_xfer_done = true;
    NRF_LOG_INFO("Transfer completed.");
    NRF_LOG_INFO(" Received %d", m_rx_buf[0]);
}

int main(void)
{
    bsp_board_init(BSP_INIT_LEDS);

    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_DEFAULT_BACKENDS_INIT();
    nrf_gpio_cfg_output(SPI_SS_PIN);
    nrf_gpio_pin_clear(SPI_SS_PIN);
    nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
    spi_config.ss_pin   = SPI_SS_PIN;
    spi_config.miso_pin = SPI_MISO_PIN;
    spi_config.mosi_pin = SPI_MOSI_PIN;
    spi_config.sck_pin  = SPI_SCK_PIN;
    spi_config.frequency = NRF_SPI_FREQ_125K;
    spi_config.mode = NRF_SPI_MODE_0;
    APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));
    NRF_LOG_INFO("SPI example started.");

    while (1)
    {
        m_tx_buf[0] = commands[counter%sizeof(commands)];
        counter = 1 - counter;
        // Reset rx buffer and transfer done flag
        memset(m_rx_buf, 0, m_length);
        spi_xfer_done = false;
        NRF_LOG_INFO("\n");
        NRF_LOG_INFO("sending %d bytes %d" , m_length, m_tx_buf[0]);
        NRF_LOG_INFO("rec buffer %d bytes %d" , m_length, m_rx_buf[0]);
        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, 1, m_rx_buf, 1));
        NRF_LOG_INFO("2\n");
        while (!spi_xfer_done)
        {
            __WFE();
        }
        NRF_LOG_FLUSH();
        bsp_board_led_invert(BSP_BOARD_LED_0);
        nrf_delay_ms(3000);
    }
}

Can anyone explain

I don't experience this problem when using RPI as SPI master with the same slave.

Anyone?