SPI RX problem (Only receive 0x00)

[Malo]

Hello,

I try to make my NRF52832 communicates with a memory (MX25R1635FZUIL0) in SPI.

When I try to read the memory ID, the RX buffer is fill with 0x00. But when I observe the MISO pin on the oscilloscope, I see the memory send some data.

I configure the SPI with the default configuration then change :

• MSB first
• mode : 3
• frequency : 8M
• miso : 9
• mosi : 15
• sck : 14
• cs : 7

I read that the pin 9 can also be used as NFC antenna (as you can see here). Is that why I can't receive anything ?

Thanks in advance for your answer.

Best regards,

Malo

[Tai]

I don't think reading in PIN 9 makes you not to receive anything. You can try other pins to check it, btw. Can you post your SPI code to read the memory ID?

[Malo]

I can't change the SPI pins on my board (it is very integrated). But I have tested exactly the same code except the SPI and memory Reset and WP pins with the DWM1001 development board connected the same memory model in a different package and it worked well with the following pins :

• miso : 7
• mosi : 6
• slk : 4
• cs : 3
• RST : 8
• WP : 15

My code is inserted below :

void Initial_Spi()
{
    nrf_gpio_pin_write(MX25_WP, 1);
    nrf_gpio_pin_write(MX25_CS, 1);

    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 = MX25_SO;
    spi_config.mosi_pin = MX25_SI;
    spi_config.sck_pin  = MX25_SCLK;
    spi_config.bit_order = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST;

    spi_config.mode = NRF_DRV_SPI_MODE_3;
    spi_config.frequency = NRF_SPI_FREQ_8M;
    
    APP_ERROR_CHECK(nrf_drv_spi_init(&MXspi, &spi_config, spi_event_handler, NULL));

    // Wait flash warm-up
    Wait_Flash_WarmUp();

    // Release the chip from powerdown mode
    CS_Low();
    SendByte( FLASH_CMD_RES, SIO );
    CS_High();

    nrf_delay_us(30000);
}

void CS_Low()
{
    nrf_gpio_pin_write(MX25_CS, 0);
}

void CS_High()
{
    nrf_gpio_pin_write(MX25_CS, 1);
    nrf_gpio_pin_write(MX25_WP, 1);
}

void SendByte( uint8_t byte_value)
{
    spi_xfer_done = false;
    APP_ERROR_CHECK(nrf_drv_spi_transfer(&MXspi, &byte_value, 1, NULL, 0));
    while(spi_xfer_done == false)
    {
      __WFE();
    }
}

uint8_t GetByte( void )
{
    uint8_t data_buf = 0;

    spi_xfer_done = false;
    APP_ERROR_CHECK(nrf_drv_spi_transfer(&MXspi, NULL, 0, &data_buf, 1));
    while(spi_xfer_done == false)
    {
      __WFE();
    }
    return data_buf;
}

ReturnMsg CMD_RDID( uint32_t *Identification )
{
    uint32_t temp;
    uint8_t  gDataBuffer[3];

    // Chip select go low to start a flash command
    CS_Low();

    // Send command
    SendByte( FLASH_CMD_RDID);

    //nrf_delay_us(10);
    // Get manufacturer identification, device identification
    gDataBuffer[0] = GetByte();
    gDataBuffer[1] = GetByte();
    gDataBuffer[2] = GetByte();
    
    // Chip select go high to end a command
    CS_High();

    // Store identification
    temp =  gDataBuffer[0];
    temp =  (temp << 8) | gDataBuffer[1];
    *Identification =  (temp << 8) | gDataBuffer[2];

    return FlashOperationSuccess;
}

Thanks,

Malo

[Malo]

I found the solution of my problem !

When you want to use a NFC pin as GPIO you have to add in the project prepocessor definitions "CONFIG_NFCT_PINS_AS_GPIOS" as explain here. This also applies to SPI pins and other protocols I imagine.

Thanks,

Malo