No MISO Responce

[JIYEON]

Hello, support team:)

Currently I am working on SPI communication with LSM6DSOXTR.

CLK, MOSI, SS is working as expected. But there is no MISO signal.

0) All SPI PIN is configured as NRF_PIN_DISCON_NOPULL

1) SPI Read function

static int32_t lsm_read(void *handle, uint8_t reg, uint8_t *bufp, uint16_t len)
{
ret_code_t err_code;
uint8_t s_tx_buf;

s_tx_buf = (reg | 0x80); // MSB 1 --> Read

spi1_xfer_done = false;

err_code = nrf_drv_spi_transfer(&m_spi_lsm, &s_tx_buf, 1, bufp, len);
RETURN_IF_ERROR(err_code);

while (!spi1_xfer_done)
{
__WFE();
}

return DRV_ACC_STATUS_CODE_SUCCESS;
}

2) WHO AM I register is 0x0FU. 

It becomes 0x8F(MSB to 1: read). And It sent to MOSI.

And 16 bit clock is created correctly.

But there is no MISO signal.

[JIYEON]

Hello,

Read function is updated. Now WHO_AM_I is read correctly.

But It seems like write function doesn't work correctly.

I wonder why delay should be done between each 8 bit in read function?

And how could I fix write function?

static int32_t lsm_write(void *handle, uint8_t reg, uint8_t *bufp, uint16_t len)
{
    ret_code_t err_code;
    uint8_t s_tx_buf[I2C_TX_LEN_MAX];
    uint8_t i;

    // Data to send: Register address + contents.
    s_tx_buf[0] = (reg ^ 0x80);
    memcpy(&s_tx_buf[1], bufp, len);
    
    nrf_gpio_pin_write(PIN_LSM_SPI_SS, 0);

    //spi1_xfer_done = false;

    //err_code = nrf_drv_spi_transfer(&m_spi_lsm, s_tx_buf, len + 1, &no_use, 1);
    //RETURN_IF_ERROR(err_code);

    //while (!spi1_xfer_done)
    //{
    //    __WFE();
    //}
    
    nrf_delay_us(5);

    for(i = 0; i < len + 1; i ++)
    {
        spi1_xfer_done = false;

        err_code = nrf_drv_spi_transfer(&m_spi_lsm, &(s_tx_buf[i]), 1, NULL, 0);
        RETURN_IF_ERROR(err_code);

        while (!spi1_xfer_done)
        {
            __WFE();
        }
    
        nrf_delay_us(1);
    }
    
    nrf_delay_us(5);

    nrf_gpio_pin_write(PIN_LSM_SPI_SS, 1);

    return DRV_ACC_STATUS_CODE_SUCCESS;   
}

static int32_t lsm_read(void *handle, uint8_t reg, uint8_t *bufp, uint16_t len)
{
    ret_code_t err_code;
    uint8_t s_tx_buf;
    uint8_t read_temp[I2C_TX_LEN_MAX] ;
    uint8_t i;

    s_tx_buf = (reg | 0x80);
    
    nrf_gpio_pin_write(PIN_LSM_SPI_SS, 0);

    nrf_delay_us(5);
    
    //spi1_xfer_done = false; 

    //err_code = nrf_drv_spi_transfer(&m_spi_lsm, &s_tx_buf, 1, read_temp, len+1);
    //RETURN_IF_ERROR(err_code);

    //while (!spi1_xfer_done)
    //{
    //    __WFE();
    //}

    //for(i = 1 ; i < len + 1 ; i ++ )
    //{
    //    bufp[i-1] = read_temp[i] ;
    //}  
    
    spi1_xfer_done = false; 

    err_code = nrf_drv_spi_transfer(&m_spi_lsm, &s_tx_buf, 1, NULL, 0);
    RETURN_IF_ERROR(err_code);

    while (!spi1_xfer_done)
    {
        __WFE();
    }
    
    nrf_delay_us(10);
    
    for(i = 0; i < len ; i ++ )
    {   
        spi1_xfer_done = false; 

        err_code = nrf_drv_spi_transfer(&m_spi_lsm, NULL, 0, &bufp[i], 1);
        RETURN_IF_ERROR(err_code);

        while (!spi1_xfer_done)
        {
            __WFE();
        }
    
        nrf_delay_us(1);
    }
    
    nrf_delay_us(5);

    nrf_gpio_pin_write(PIN_LSM_SPI_SS, 1);
    
    return DRV_ACC_STATUS_CODE_SUCCESS;
}

[Susheel Nuguru]

What is the context in which you are calling lsm_read? probably the answer to that question might give some hints as to why replacing __WFE with busy delay helps in your case. I have not seen into the timing requirement of your sensor.

5us delay does not look bad in a lower priority threads, so if it works, keep it.