NRF 5340 spi4 communication, SDK 3.0.1

Question

Hello,

I am trying to send and receive data from an external slave sensor using the NRF5340. For debugging purposes, I have connected the NRF5340 to my PC via UART.

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/drivers/uart.h>
#include <zephyr/drivers/gpio.h> // Include GPIO header file
#include <zephyr/sys/printk.h>
#include <zephyr/sys/byteorder.h> // Include for byte order conversion functions (if necessary)
#include <stdio.h> // printk can be used via stdio.h or zephyr/sys/printk.h

/* Get SPI device from Devicetree */
#define SPI_DEVICE_NODE DT_ALIAS(spi4_basic) // Set to the DT alias of the actual SPI controller being used
static const struct device *spi_dev = DEVICE_DT_GET(SPI_DEVICE_NODE);
// It's just getting it in two steps instead of all at once. Ultimately, it gets spi_dev.

/* Get UART device from Devicetree (uses the same UART as printk) */
static const struct device *uart_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_console));

/* Get Chip Select pin configuration from Devicetree */
static const struct spi_cs_control cs_ctrl = SPI_CS_GPIOS_DT_SPEC_GET(SPI_DEVICE_NODE);

/* RHD2000 SPI Configuration */
// RHD2000 uses SPI Mode 0 (CPOL=0, CPHA=0)
// Data is 16-bit, MSB first
static struct spi_config spi_cfg = {
    .frequency = 560000,      // SPI frequency
    .operation = SPI_OP_MODE_MASTER | SPI_WORD_SET(16) | SPI_TRANSFER_MSB, // Default settings: CPOL=0, CPHA=0
    .slave = 0,
    .cs = cs_ctrl,
};



/* 16-bit SPI Communication Helper Function */
static int rhd_spi_transfer(uint16_t tx_command, uint16_t *rx_data)
{
    uint16_t mosi_word = tx_command;
    uint16_t miso_word = 0;

    struct spi_buf tx_buf = { .buf = &mosi_word, .len = sizeof(mosi_word) };
    const struct spi_buf_set tx_bufs = { .buffers = &tx_buf, .count = 1 }; // count: Information on how many parts it will be divided into

    struct spi_buf rx_buf = { .buf = &miso_word, .len = sizeof(miso_word) };
    const struct spi_buf_set rx_bufs = { .buffers = &rx_buf, .count = 1 };

    int err;

    // spi_dev itself is an address. Others (spi_cfg, etc.) are structs.
    printk("Calling spi_transceive()\n");
    err = spi_transceive(spi_dev, &spi_cfg, &tx_bufs, &rx_bufs);
    printk("spi_transceive() completed\n");
    if (err) {
        printk("spi_transceive() failed with error %d\n", err);
        return err;
    }

    if (rx_data) {
        *rx_data = miso_word;
    }
    return 0;
}

/* RHD2132 Initialization Function */
int main(void)
{
    uint16_t miso_val;
    int err;

    printk("Executing initialization function.\n");
    k_msleep(1000); // Wait for 1000 milliseconds (1 second)

    // According to the RHD2000 datasheet, a dummy SPI transaction may be required for initialization
    rhd_spi_transfer(RHD_CMD_DUMMY_READ, &miso_val); // transfer
    printk("Dummy1.\n");

    return 0;
}

To get to the point, the problem I'm facing is that the spi_transceive() function seems to be stuck in an infinite loop.

The message "Calling spi_transceive()" is printed, but there is no response after that.

I suspect there might be an issue with how the CS pin is being handled, but I'm not sure what the exact problem is.

I have also attached the .conf and .overlay files I am using.

CONFIG_UART_CONSOLE=y


CONFIG_SERIAL=y
CONFIG_PRINTK=y

# Kernel
CONFIG_MAIN_STACK_SIZE=2048

CONFIG_SPI=y
CONFIG_GPIO=y 
CONFIG_GPIO_NRFX=y

/ {
    chosen {
        zephyr,console = &uart0;    
        zephyr,shell-uart = &uart0; 
    };

    aliases {
        spi4-basic = &spi4;         
    };
};


&uart0 {
    status = "okay";             
    current-speed = <1000000>;    
};


&pinctrl {
    spi4_custom_pins: spi4_custom_pins { 
        group1 {
            psels = <NRF_PSEL(SPIM_SCK,  1, 15)>,   
                    <NRF_PSEL(SPIM_MOSI, 1, 14)>,  
                    <NRF_PSEL(SPIM_MISO, 1, 13)>;  
        };
    };


    spi4_custom_pins_sleep: spi4_custom_pins_sleep {
         group1 {
            psels = <NRF_PSEL(SPIM_SCK,  1, 15)>,
                    <NRF_PSEL(SPIM_MOSI, 1, 14)>,
                    <NRF_PSEL(SPIM_MISO, 1, 13)>;
            low-power-enable; 
        };
    };
};


&spi4 {
    compatible = "nordic,nrf-spim";
    status = "okay"; 
    pinctrl-0 = <&spi4_custom_pins>; 
    pinctrl-1 = <&spi4_custom_pins_sleep>; 
    pinctrl-names = "default", "sleep";   
    cs-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>; 
};

Thank you.

Best regards, Minseok Kim