hardware CS not working when using BLE with nRF5340DK

[Nicolas Brunner]

Hello,

I'm using NCS 1.4.99 with a nRF5340DK and want to use the hardware CS of the SPI and also use BLE.

Here is a simple code that work on a nRF5340PDK but only work on a nRF5340DK when CONFIG_BT is not defined.

Fullscreen 0777.main.c Download

/* Includes ------------------------------------------------------------------*/

#include <assert.h>
#include <stdint.h>

#include <nrfx_spim.h>

/* Private define ------------------------------------------------------------*/

#define SPI_TRANSFER_SIZE 2
#define TX_DATA 0x1234

#define SCLK_PIN NRF_GPIO_PIN_MAP(1, 5)
#define MOSI_PIN NRF_GPIO_PIN_MAP(1, 4)
#define MISO_PIN NRF_GPIO_PIN_MAP(1, 6)
#define CSN_PIN  NRF_GPIO_PIN_MAP(1, 1)

/* Private variables ---------------------------------------------------------*/

static uint8_t rx_buffer[SPI_TRANSFER_SIZE];
static uint8_t tx_buffer[SPI_TRANSFER_SIZE];

static const nrfx_spim_t spi = NRFX_SPIM_INSTANCE(4);
static const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TRX(tx_buffer, SPI_TRANSFER_SIZE, rx_buffer, SPI_TRANSFER_SIZE);

/* Public functions ----------------------------------------------------------*/

void main(void)
{
    nrfx_err_t err_code;

    nrfx_spim_config_t spi_config = NRFX_SPIM_DEFAULT_CONFIG(
            SCLK_PIN,
            MOSI_PIN,
            MISO_PIN,
            NRFX_SPIM_PIN_NOT_USED);
    spi_config.frequency = NRF_SPIM_FREQ_8M;
    spi_config.mode = NRF_SPIM_MODE_0;

    err_code = nrfx_spim_init(&spi, &spi_config, NULL, NULL);
    assert(err_code == NRFX_SUCCESS);
    spi.p_reg->PSEL.CSN = CSN_PIN; // workaround, if set in spi_config, the CS pin is set/clear by software

    tx_buffer[0] = (TX_DATA >> 8) & 0xFF;
    tx_buffer[1] = TX_DATA & 0xFF;

    while(1) {
        nrfx_spim_xfer(&spi, &xfer, NRFX_SPIM_FLAG_NO_XFER_EVT_HANDLER);
    }
}

7077.prj.conf.

[Einar Thorsrud]

Hi,

I tested your code and I see that the CS pin toggles as expected when CONFIG_BT is set to n but not when set to y. I am not able to explain this right now though so I need to get back to you tomorrow.

Edit: I just noticed that this issue only occurs when building for secure mode (nrf5340dk_nrf5340_cpuapp). Building for non-secure (nrf5340dk_nrf5340_cpuappns) CS works as expected.

[Nicolas Brunner]

Thanks for this information but what do I need to do to run it in non-secure ?

I have tried with SES to build it for non-secure but it crash when calling nrfx_spim_init().

After that, I saw that SPM was not listing SPIM4 to the console, so i use SPIM3 because it was listed. Now my code get stuck in nrfx_spim_xfer() waiting for NRF_SPIM_EVENT_END that never come.

[Einar Thorsrud]

Hi,

To build for non-secure mode you select nrf5340dk_nrf5340_cpuappns as the board instead of nrf5340dk_nrf5340_cpuapp. But for this issue in general I do not yet understand what causes this nor do I have any other proposed fix at this point. I will look more into it, though.

[Nicolas Brunner]

Thanks, it's what I did but I got the problems described in my previous message.

[Einar Thorsrud]

Hi,

The actual issue here is that P1.1 (33) is used by the network core. So the fix is to use another pin. I have tested with P1.3, and with that it works as expected with both secure and non-secure, using both west on the command line and SES.