Thingy91 SPI basic communication with ADXL362

[krupis]

Hello everyone. I have been having nightmares trying to set up basic communication between nRF9160 on the thingy 91 and the ADXL362 sensor.
I ticket on the nordic devzone has already been created here:
https://devzone.nordicsemi.com/f/nordic-q-a/105665/thingy-91-spi-driver-for-adxl362

I have tried 2 different methods:
method1:

#include <stdio.h>
#include <stdlib.h>
#include <zephyr/kernel.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/device.h>

#define LOG_LEVEL CONFIG_LOG_DEFAULT_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(main);

#define ADXL362_WRITE_REG 0x0A
#define ADXL362_READ_REG 0x0B
#define ADXL362_READ_FIFO 0x0D

#define ADXL362_REG_DEVID_AD 0x00

static int readRegister(uint8_t reg, uint8_t *values, uint8_t size);

#define MY_SPI_MASTER DT_ALIAS(adxl362)
struct spi_dt_spec spec = SPI_DT_SPEC_GET(DT_NODELABEL(adxl362), SPI_WORD_SET(8) | SPI_MODE_GET(0), 1);

int main(void)
{
	int err;
	printk("Program started \n");
	if (spi_is_ready(&spec) == true)
	{
		printk("SPI is ready \n");
	}
	else
	{
		printk("SPI is not ready \n");
	}

	uint8_t values[1];
	while (1)
	{
		int ret = readRegister(ADXL362_REG_DEVID_AD, values, 1);
		if (ret == 0)
		{
			printk("Read chip ID failed \n");
			k_msleep(1000);
		}
		else
		{
			printk("Register chip ID:%.2x\n", values[0]);
			k_msleep(1000);
		}
	}
	return 0;
}






// According to the ADXL362 datasheet (https://www.analog.com/media/en/technical-documentation/data-sheets/adxl362.pdf)
// Figure 36, we follow multi byte structure where first byte is ADXL362_READ_REG and second byte is the register address
static int readRegister(uint8_t reg, uint8_t *values, uint8_t size)
{
	int err;
	uint8_t tx_buffer[2];
	tx_buffer[0] = ADXL362_READ_REG;
	tx_buffer[1] = reg;

	struct spi_buf tx_spi_buf = {
		.buf = tx_buffer,
		.len = sizeof(tx_buffer)};

	struct spi_buf_set spi_tx_buffer_set = {
		.buffers = &tx_spi_buf,
		.count = 1};

	struct spi_buf rx_spi_buf = {
		.buf = values,
		.len = size};

	struct spi_buf_set spi_rx_buffer_set = {
		.buffers = &rx_spi_buf,
		.count = 1};

	err = spi_transceive_dt(&spec, &spi_tx_buffer_set, &spi_rx_buffer_set);

	if (err)
	{
		printk("SPI error: %d\n", err);
		return 0;
	}
	return 1;
}

Serial logs result:

Method2:

#include <stdio.h>
#include <stdlib.h>
#include <zephyr/kernel.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/device.h>
#include <zephyr/drivers/gpio.h>

#define LOG_LEVEL CONFIG_LOG_DEFAULT_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(main);

#define ADXL362_WRITE_REG 0x0A
#define ADXL362_READ_REG 0x0B
#define ADXL362_READ_FIFO 0x0D

#define ADXL362_REG_DEVID_AD 0x00

static int readRegister(uint8_t reg, uint8_t *values, uint8_t size);

#define DEFAULT_ADXL362_NODE DT_ALIAS(adxl362)
BUILD_ASSERT(DT_NODE_HAS_STATUS(DEFAULT_ADXL362_NODE, okay),
			 "ADXL362 not specified in DT");

// DEVICE TREE STRUCTURE
const struct device *adxl1362_sens = DEVICE_DT_GET(DEFAULT_ADXL362_NODE);

// CS CONTROL
struct spi_cs_control ctrl = {
	.gpio = SPI_CS_GPIOS_DT_SPEC_GET(DT_NODELABEL(adxl362)),
	.delay = 2,
};

// SPI CONFIG
static const struct spi_config spi_cfg = {
	.operation = SPI_WORD_SET(8) | SPI_TRANSFER_MSB,
	.frequency = 1000000, // 1 mhz
	.slave = 0,
	.cs = &ctrl,
};

int main(void)
{
	int err;
	printk("Program started \n");
	if (!device_is_ready(adxl1362_sens))
	{
		printk("sensor: device %s not ready.\n", adxl1362_sens->name);
		return 0;
	}
	uint8_t values[1];
	while (1)
	{
		int ret = readRegister(ADXL362_REG_DEVID_AD, values, 1);
		if (ret == 0)
		{
			printk("Read chip ID failed \n");
			k_msleep(1000);
		}
		else
		{
			printk("Register chip ID: %d\n", values[0]);
			k_msleep(1000);
		}
	}
	return 0;
}

// According to the ADXL362 datasheet (https://www.analog.com/media/en/technical-documentation/data-sheets/adxl362.pdf)
// Figure 36, we follow multi byte structure where first byte is ADXL362_READ_REG and second byte is the register address
static int readRegister(uint8_t reg, uint8_t *values, uint8_t size)
{
	int err;
	uint8_t tx_buffer[2];
	tx_buffer[0] = ADXL362_READ_REG;
	tx_buffer[1] = reg;

	struct spi_buf tx_spi_buf = {
		.buf = tx_buffer,
		.len = sizeof(tx_buffer)};

	struct spi_buf_set spi_tx_buffer_set = {
		.buffers = &tx_spi_buf,
		.count = 1};

	struct spi_buf rx_spi_buf = {
		.buf = values,
		.len = size};

	struct spi_buf_set spi_rx_buffer_set = {
		.buffers = &rx_spi_buf,
		.count = 1};

	err = spi_transceive(adxl1362_sens, &spi_cfg, &spi_tx_buffer_set, &spi_rx_buffer_set);
	if (err)
	{
		printk("SPI error: %d\n", err);
		return 0;
	}
	return 1;
}

Serial logs:

As you can see, I cannot properly read the device ID using either of the SPI methods. I believe there might be some issue in the way I setup my SPI in my code but I cannot spot any mistakes myself... I would highly appreciate if someone could look at the code and see if it looks good.

Both projects can be accessed via my repository:

Method 1: https://github.com/krupis/thingy91_spi_test/tree/method1
Method 2: https://github.com/krupis/thingy91_spi_test/tree/method2

You can easily recreate the issue if you have Thingy 91 board by programming either method1 or method2 on the nRF9160 and have the connectivity bridge application running on the nRF52840.