SPI AND SPIM READING ISSUES

[NANDHU]

hi all i am trying to read data from a sensor in burst mode i can"t able to read all datas from the register .I tried to read the data in both spi and spim(with easydma) . spim is more better it reads data from 2 register(i am trying to read data of 3 register using burst mode).how can i solve this issues.

[hmolesworth]

I assume you control NCS correctly, setting low before the first of two transfers and only high after the second with the 4 uSec delay between the two transfers. However your code shows that you are also telling the nRF SPI code to take control of NCS. Here is the default setting for NCS and the handler for init:

// Starts by assuming NCS is not required

/**
 * @brief SPI master instance default configuration.
 */
#define NRF_DRV_SPI_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_4M,                     \
    .mode         = NRF_DRV_SPI_MODE_0,                      \
    .bit_order    = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST,         \
}

// Tests if NCS is not required

    // - Slave Select (optional) - output with initial value 1 (inactive).
    if (p_config->ss_pin != NRF_DRV_SPI_PIN_NOT_USED)
    {
        nrf_gpio_pin_set(p_config->ss_pin);
        nrf_gpio_cfg_output(p_config->ss_pin);
    }
    m_cb[p_instance->drv_inst_idx].ss_pin = p_config->ss_pin;

However your code shows that you are requesting the nRF SPI driver to take over NCS:

spi_config.ss_pin = SPI_MOUSE_CSN_PIN;

The nRF handler will now drive NCS low before and high after every transaction, including between the two transactions you require, for example sww nrf_drv_spi.c

static void finish_transfer(spi_control_block_t * p_cb)
{
    // If Slave Select signal is used, this is the time to deactivate it.
    if (p_cb->ss_pin != NRF_DRV_SPI_PIN_NOT_USED)
    {
        nrf_gpio_pin_set(p_cb->ss_pin);
    }

[NANDHU]

so i want to remove this  "spi_config.ss_pin = SPI_MOUSE_CSN_PIN;" portion from the code  then only i get correct data from burst mode read.

[NANDHU]

pls reply sir

[hmolesworth]

Yes, I thought I made that clear. You require the following if you are manually driving NCS before and after the two transfers:

spi_config.sck_pin = NRF_DRV_SPI_PIN_NOT_USED;

This is the default, as I posted above, so you can also just remove .sck_pin in initialisation

[NANDHU]

thanks for your clarification i will try it

[NANDHU]

SIR I CHANGED "spi_config.ss_pin = SPI_MOUSE_CSN_PIN;" TO "spi_config.sck_pin = NRF_DRV_SPI_PIN_NOT_USED;

BUT I CAN"T ABLE TO READ DATA FROM ALL 3 REGISTERS

[NANDHU]

CONFIGURATION OF SPI

nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
spi_config.ss_pin = NRF_DRV_SPI_PIN_NOT_USED;
spi_config.miso_pin = SPI_MOUSE_MISO_PIN;
spi_config.mosi_pin = SPI_MOUSE_MOSI_PIN;
spi_config.sck_pin = SPI_MOUSE_SCK_PIN;
spi_config.frequency = NRF_SPI_FREQ_1M;
spi_config.bit_order = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST;
spi_config.irq_priority = SPI_DEFAULT_CONFIG_IRQ_PRIORITY;
spi_config.mode = NRF_DRV_SPI_MODE_0;
spi_config.orc = 0xFF;

err_code = nrf_drv_spi_init(&spi, &spi_config,NULL, NULL);
if(err_code != NRF_SUCCESS)
return NRF_ERROR_SPI;

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

FUNCTION FOR READING DATA IN BURST MODE

uint32_t adns_motion_burst_read(const nrf_drv_spi_t * i_spi_address , uint8_t * motion , uint8_t * deltaY , uint8_t * deltaX)
{

     uint32_t err_code;

     if (i_spi_address == NULL )
     {
         return NRF_ERROR_INVALID_PARAM;
     }

     uint8_t tx_bm_data;
     uint8_t rx_bm_dummy; //receive buffer for dummy
     uint8_t i_reg;

    // Reset serial port
     adns_ncs_assert(i_spi_address,1); //disable ncs
     adns_ncs_assert(i_spi_address,0); //enable nc

     i_reg = ADNS_REG_MOTION_BURST;
    // Format for register in burstmode read
     tx_bm_data = i_reg & 0x7f; // The MSB to "0" to indicate a read operation

   // Write to Motion_Burst register.
     APP_ERROR_CHECK(nrf_drv_spi_transfer(i_spi_address,(const uint8_t  *)&tx_bm_data,1,&rx_bm_dummy,1));
   *motion = rx_bm_dummy; // Execute dummy read to clear RX buffer for motion


     nrf_delay_us(4); //tSRAD

   //Read motion datas by Writing out a dummy data byte which will be ignored 
     APP_ERROR_CHECK(nrf_drv_spi_transfer(i_spi_address,(const uint8_t  *)&tx_bm_dummy[0],3,&rx_bm_data[0],3));

    adns_ncs_assert(i_spi_address,1); //disable ncs


    *motion = rx_bm_data[0];
    *deltaY = rx_bm_data[1];
    *deltaX = rx_bm_data[2];

     nrf_delay_us(1); //tBEXIT

     return NRF_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

sdk_config.h

#ifndef SPI0_ENABLED
#define SPI0_ENABLED 1
#endif
// <q> SPI0_USE_EASY_DMA - Use EasyDMA

#ifndef SPI0_USE_EASY_DMA
#define SPI0_USE_EASY_DMA 0
#endif

[NANDHU]

when i debugged it shows the value of all three register once then no value is reading

[NANDHU]

          

look the screen short i can get the value only once in the intial then it well not get

[NANDHU]

              

THIS IS HOW WE WANT TO READ

[Jørgen Holmefjord]

Try changing tx_bm_dummy to NULL in second call to nrf_drv_spi_transfer, and set the tx_length parameter to 0. In your current code you will write three bytes from whatever you have initialized tx_bm_dummy to (or garbage data from RAM if not initialized), to the SPI slave. The peripheral will automatically clock out dummy bytes when you do a read operation.

You say that you can only receive the data once, how do you start the transfer? Have you tried debugging the application, to see if any error codes are reported?