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Using nrf52832 as SPI master to get data from sensor

Hi All,

I'm trying to use the nrf52832 as the SPI master to get sensor reading through spi from another sensor. I want to base my firmware on the spi_pca10040 example but I don't know what the change except the pin number for CS, MISO, MOSI, and SCLK and the length of the tx and rx buffer. (since the sensor send 32 bits data)

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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"

#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[4];           /**< TX buffer. */
static uint8_t       m_rx_buf[4];    /**< RX buffer. */
static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */

/**
 * @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.");
    if (m_rx_buf[0] != 0)
    {
        NRF_LOG_INFO(" Received:");
        NRF_LOG_HEXDUMP_INFO(m_rx_buf, strlen((const char *)m_rx_buf));
    }
}

int main(void)
{
    bsp_board_init(BSP_INIT_LEDS);

    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_DEFAULT_BACKENDS_INIT();

    nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
    spi_config.ss_pin   = 29; //SPI_SS_PIN;
    spi_config.miso_pin = 28; //SPI_MISO_PIN;
    spi_config.mosi_pin = 4; //SPI_MOSI_PIN;
    spi_config.sck_pin  = 3; //SPI_SCK_PIN;
    APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));

    NRF_LOG_INFO("SPI example started.");

    while (1)
    {
        // Reset rx buffer and transfer done flag
        memset(m_rx_buf, 0, m_length);
        spi_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));

        while (!spi_xfer_done)
        {
            __WFE();
        }

        NRF_LOG_FLUSH();

        bsp_board_led_invert(BSP_BOARD_LED_0);
        nrf_delay_ms(200);
    }
}
 

This is what I have so far. Any advice?

Thanks,

Vincent

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  • Hi Vincent,

    It will depend on your sensor, but usually you would need to specify the adress from which you want to read from in the first byte. Could you specify which sensor are you trying to read data from so I can help you more?
    And if you specify from which adress to read from in the first byte you will need an extra byte to read the 4 bytes of data that the sensor send, so the length of both TX and RX buffers should be set to 5 bytes in this case.

    Best Regards,

    Marjeris

Reply
  • Hi Vincent,

    It will depend on your sensor, but usually you would need to specify the adress from which you want to read from in the first byte. Could you specify which sensor are you trying to read data from so I can help you more?
    And if you specify from which adress to read from in the first byte you will need an extra byte to read the 4 bytes of data that the sensor send, so the length of both TX and RX buffers should be set to 5 bytes in this case.

    Best Regards,

    Marjeris

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