Questions about spi read and write function mapping

RE: Questions about spi read and write function mapping

rayan4444 — Sun, 29 Aug 2021 10:33:10 GMT

I am facing the exact same issues with the exact same sensor. including 0xFF chip ID.
Could you share the solution you found in the end (spi read and write functions)? or a perhaps a link to a repository with a working example?

RE: Questions about spi read and write function mapping

June6 — Tue, 04 Aug 2020 10:29:13 GMT

Hi,

I use Bosch driver, there is no problem at all. Here is my SPI configuration:

#define NRF_DRV_SPI_BMI088_DEFAULT_CONFIG                    \
{                                                            \
    .sck_pin      = NRF_DRV_SPI_PIN_NOT_USED,                \
    .mosi_pin     = NRF_DRV_SPI_PIN_NOT_USED,                \
    .miso_pin     = NRF_DRV_SPI_PIN_NOT_USED,                \
    .ss_pin       = NRF_DRV_SPI_PIN_NOT_USED,                \
    .irq_priority = SPI_DEFAULT_CONFIG_IRQ_PRIORITY,         \
    .orc          = 0xFF,                                    \
    .frequency    = NRF_DRV_SPI_FREQ_8M,                     \
    .mode         = NRF_DRV_SPI_MODE_0,                      \
    .bit_order    = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST,         \
}

#define SPI_INSTANCE_0                  0                                           /**< SPI instance index. */

static const nrf_drv_spi_t spi_0_bmi088 = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE_0);     /**< SPI instance. */


nrf_drv_spi_config_t spi_bmi088_config = NRF_DRV_SPI_BMI088_DEFAULT_CONFIG;

nrf_gpio_cfg_output(MCU_GPIO_BMI088_CSB1);
nrf_gpio_cfg_output(MCU_GPIO_BMI088_CSB2);
nrf_gpio_pin_set(MCU_GPIO_BMI088_CSB1);
nrf_gpio_pin_set(MCU_GPIO_BMI088_CSB2);

spi_bmi088_config.ss_pin   = NRF_DRV_SPI_PIN_NOT_USED;
spi_bmi088_config.miso_pin = SPI_BMI088_MISO_PIN;
spi_bmi088_config.mosi_pin = SPI_BMI088_MOSI_PIN;
spi_bmi088_config.sck_pin  = SPI_BMI088_SCK_PIN;
APP_ERROR_CHECK(nrf_drv_spi_init(&spi_0_bmi088, &spi_bmi088_config, spi_bmi088_event_handler, NULL));

RE: Questions about spi read and write function mapping

pradeepyadav — Tue, 04 Aug 2020 10:07:36 GMT

Hi june6,

i got the same issue , i am trying to interface spi nor flash with nRF52840 but not able to read the device ID?

RE: Questions about spi read and write function mapping

June6 — Thu, 09 Jan 2020 07:30:51 GMT

Although I have solved the problem myself, thank you for replying to me!

RE: Questions about spi read and write function mapping

haakonsh — Mon, 06 Jan 2020 15:20:37 GMT

Sorry for the long wait.

The read function should look like this:

int8_t user_spi_read(uint8_t cs_pin, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
    nrfx_err_t ret_code = NRFX_SUCCESS;
    nrfx_spim_xfer_desc_t my_xfer_desc = NRFX_SPIM_XFER_RX(&data, (len + 1));
    
    uint8_t m_tx_buf[MAX_LENGTH];   // create buffer
    memset(&m_tx_buf, 0, sizeof(m_tx_buf)); //clear buffer
    
    m_tx_buf[0] = (1 << 0) | (reg_addr << 1);
    
    /* Configure the Chip Select pin, SPIM3 supports HW controlled CS pin*/
    NRF_SPIM3->PSEL.CSN = cs_pin;
    
    ret_code = nrfx_spim_xfer(&my_spim_instance, my_xfer_desc, flags);
    APP_ERROR_CHECK(ret_code);
    
    return;
}

RE: Questions about spi read and write function mapping

hmolesworth — Tue, 10 Dec 2019 03:31:42 GMT

The read function shown seems to be doing a write since the LS bit is '0':

int8_t user_spi_read(uint8_t cs_pin, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
    nrf_gpio_pin_clear(cs_pin);
    nrf_delay_us(1);
    if(len<=255)
    {
        uint8_t m_tx_buf[1] = {0};

I would expect setting the LS bit to '1' would perform a read, but that is either MSB first or LS Bit first, not sure which for this part:

int8_t user_spi_read(uint8_t cs_pin, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
    nrf_gpio_pin_clear(cs_pin);
    nrf_delay_us(1);
    if(len<=255)
    {
        uint8_t m_tx_buf[1] = {0x01}; // if MS Bit first
        uint8_t m_tx_buf[1] = {0x80}; // if LS Bit first

It would help if you show both initialisation code (use SPI Mode 0) and detail pin connections as this part is not a simple SPI part (eg accelerometer has to be changed from I2C to SPI).

RE: Questions about spi read and write function mapping

June6 — Tue, 10 Dec 2019 02:23:27 GMT

peripheral\spi

RE: Questions about spi read and write function mapping

haakonsh — Thu, 05 Dec 2019 16:01:04 GMT

Where do you set spi_bmi088_xfer_done after the transfer is complete?

what SDK and driver are you using?

RE: Questions about spi read and write function mapping

June6 — Wed, 04 Dec 2019 09:50:14 GMT

please reply to me quickly！

Thanks！

RE: Questions about spi read and write function mapping

June6 — Wed, 04 Dec 2019 09:49:38 GMT

Are the above function mapping operations normal?

Which engineer can answer me？

RE: Questions about spi read and write function mapping

June6 — Wed, 04 Dec 2019 09:48:16 GMT

At present, in the process of communicating with the BMI088 sensor, I suspect that the spi read and write commands are abnormal. In order to determine that the function mapping I made is not a problem, I will paste a piece of function mapping code below.

/*!
 *  @brief Function for reading the sensor's registers through SPI bus.
 *
 *  @param[in] cs_pin   : Chip selection pin.
 *  @param[in] reg_addr : Register address.
 *  @param[in] data     : Pointer to the data buffer to store the read data.
 *  @param[in] len      : No of bytes to read.
 *
 *  @return Status of execution
 *  @retval 0 -> Success
 *  @retval >0 -> Failure Info
 *
 */
int8_t user_bmi088_spi_write(uint8_t cs_pin, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
    if (cs_pin == MCU_GPIO_BMI088_CSB1)
    {
        nrf_gpio_pin_set(MCU_GPIO_BMI088_CSB2);
        nrf_gpio_pin_clear(MCU_GPIO_BMI088_CSB1);
    }
    else if (cs_pin == MCU_GPIO_BMI088_CSB2)
    {
        nrf_gpio_pin_set(MCU_GPIO_BMI088_CSB1);
        nrf_gpio_pin_clear(MCU_GPIO_BMI088_CSB2);
    }
    else if ((cs_pin != MCU_GPIO_BMI088_CSB1) && (cs_pin != MCU_GPIO_BMI088_CSB2))
    {
        return -2;
    }
    nrf_delay_us(1);
    if (len <= 32)
    {
        uint8_t m_tx_buf[33] = {0};
        m_tx_buf[0] = reg_addr;
        uint8_t m_tx_length = ((uint8_t)len) + 1;
//        const uint8_t m_rx_length = 0;
        memcpy(&m_tx_buf[1], &data, len);

        spi_bmi088_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi_0, m_tx_buf, m_tx_length, NULL, 0));
        while(!spi_bmi088_xfer_done)
        {
            __WFE();
        }
    }
    else
    {
        NRF_LOG_INFO("Spi write over length.");
    }
    nrf_delay_us(1);
    nrf_gpio_pin_set(cs_pin);

    return 0;
}


/*!
 *  @brief Function for writing the sensor's registers through SPI bus.
 *
 *  @param[in] cs_pin   : Chip selection pin.
 *  @param[in] reg_addr : Register address.
 *  @param[out]data     : Pointer to the data buffer whose value is to be written.
 *  @param[in] len      : No of bytes to write.
 *
 *  @return Status of execution
 *  @retval 0 -> Success
 *  @retval >0 -> Failure Info
 *
 */
int8_t user_bmi088_spi_read(uint8_t cs_pin, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
    if (cs_pin == MCU_GPIO_BMI088_CSB1)
    {
        nrf_gpio_pin_set(MCU_GPIO_BMI088_CSB2);
        nrf_gpio_pin_clear(MCU_GPIO_BMI088_CSB1);
    }
    else if (cs_pin == MCU_GPIO_BMI088_CSB2)
    {
        nrf_gpio_pin_set(MCU_GPIO_BMI088_CSB1);
        nrf_gpio_pin_clear(MCU_GPIO_BMI088_CSB2);
    }
    else if ((cs_pin != MCU_GPIO_BMI088_CSB1) && (cs_pin != MCU_GPIO_BMI088_CSB2))
    {
        return -2;
    }
    nrf_delay_us(1);
    if (len <= 32)
    {
        uint8_t m_tx_buf[1] = {reg_addr};
        uint8_t m_tx_length = 1;
        uint8_t m_rx_length = (uint8_t)len;
				
        spi_bmi088_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi_0, m_tx_buf, m_tx_length, data, m_rx_length));
        while(!spi_bmi088_xfer_done)
        {
            __WFE();
        }
    }
    else
    {
        NRF_LOG_INFO("Spi read over length.");
    }
    nrf_delay_us(1);
    nrf_gpio_pin_set(cs_pin);

    return 0;
}

RE: Questions about spi read and write function mapping

June6 — Tue, 03 Dec 2019 01:24:26 GMT

I have solved the above problem.

RE: Questions about spi read and write function mapping

June6 — Mon, 02 Dec 2019 03:07:23 GMT

I try to call bmi08a_init, there is an operation to read the chip ID in this function, but the value read is always 0xFF, (correct 0x1E). Where am I wrong about the mapping of SPI reads and writes?

RE: Questions about spi read and write function mapping

June6 — Mon, 02 Dec 2019 02:59:36 GMT

SPI timing is

RE: Questions about spi read and write function mapping

June6 — Mon, 02 Dec 2019 02:57:56 GMT

My approach is as follows:

int8_t user_spi_read(uint8_t cs_pin, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
    nrf_gpio_pin_clear(cs_pin);
    nrf_delay_us(1);
    if(len<=255)
    {
        uint8_t m_tx_buf[1] = {0};
        uint8_t m_tx_length = 1;
        uint8_t m_rx_length = (uint8_t)len;
        m_tx_buf[0] = reg_addr;

        // Reset rx buffer and transfer done flag
        memset(m_rx_buf, 0, m_rx_length);
        spi_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_tx_length, m_rx_buf, m_rx_length));
        while (!spi_xfer_done)
        {
            __WFE();
        }
        memcpy_fast(data, m_rx_buf, m_rx_length);
    }
    else
    {
        NRF_LOG_DEBUG("Spi read over length.");
    }
    nrf_delay_us(1);
    nrf_gpio_pin_set(cs_pin);
}


int8_t user_spi_write(uint8_t cs_pin, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
    nrf_gpio_pin_clear(cs_pin);
    nrf_delay_us(1);
    if(len<=255)
    {
        uint8_t m_tx_buf[255] = {0};
        uint8_t m_length = (uint8_t)len;
        m_tx_buf[0] = reg_addr;
        memcpy(&m_tx_buf[1], data, strlen(data));
  
        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));
    }
    else
    {
        NRF_LOG_DEBUG("Spi write over length.");
    }
    nrf_delay_us(1);
    nrf_gpio_pin_set(cs_pin);
}