RE: Getting zeros from ISM330DHCX accelerometers

ahmed almaghasilah — Thu, 29 Aug 2024 02:28:10 GMT

Hello Kazi,

Thank you so much for bring this to my attention. I was not aware there was a driver for sensors from ST. I was under the impression that Zephyr/nRF drivers is capable by itself in handling it.

At first when I added CONFIG_ISM330DHCX=y in project configuration file (prj.conf), an error popped up and I was not sure. The moment I built/flashed the kit, there was no error. I finally made it work. Thank you so much Kazi!

Here is my final code for others who might run into same issue or first time in nRF and ST sensors:

main.c

#include <zephyr/device.h>
#include <zephyr/drivers/i2c.h>
#include <zephyr/drivers/sensor.h>
#include <zephyr/sys/printk.h>
#include <zephyr/kernel.h>

#define ISM330DHCX_I2C_ADDR 0x6A

void main(void)
{
    const struct device *sensor = DEVICE_DT_GET_ONE(st_ism330dhcx);
    int ret;

    if (!device_is_ready(sensor)) {
        printk("Sensor device not found\n");
        return;
    }

    // Example setup for 104 Hz ODR, ±4g full scale
    uint8_t config1[] = {0x10, 0x88}; // CTRL1_XL: ODR=104 Hz, FS=±4g
    struct i2c_dt_spec i2c_dev = I2C_DT_SPEC_GET(DT_NODELABEL(mysensor));
    ret = i2c_write_dt(&i2c_dev, config1, sizeof(config1));
    if (ret != 0) {
        printk("Failed to configure ISM330DHCX CTRL1_XL (error: %d)\n", ret);
        return;
    } else {
        printk("ISM330DHCX configured successfully\n");
    }

    uint8_t raw_data[6];
    struct sensor_value accel[3];

    while (1) {
        ret = sensor_sample_fetch(sensor);
        if (ret) {
            printk("Sensor sample update error: %d\n", ret);
            continue;
        }

        // Read raw accelerometer data registers directly
        ret = i2c_burst_read(i2c_dev.bus, ISM330DHCX_I2C_ADDR, 0x28, raw_data, sizeof(raw_data));
        if (ret == 0) {
            // printk("Raw data: X_L=%02x X_H=%02x Y_L=%02x Y_H=%02x Z_L=%02x Z_H=%02x\n",
            //     raw_data[0], raw_data[1],
            //     raw_data[2], raw_data[3],
            //     raw_data[4], raw_data[5]);

            // Interpret the raw data into signed 16-bit integers
            int16_t raw_x = (int16_t)(raw_data[1] << 8 | raw_data[0]);
            int16_t raw_y = (int16_t)(raw_data[3] << 8 | raw_data[2]);
            int16_t raw_z = (int16_t)(raw_data[5] << 8 | raw_data[4]);

            // printk("Raw interpreted data: X=%d, Y=%d, Z=%d\n", raw_x, raw_y, raw_z);

            // Convert raw values to m/s^2 ( 1g = 9.80665 m/s^2)
            // const double scale = 9.80665 / 2050.0; // Convert from raw to m/s^2 - 16g
            const double scale = 9.80665 / 8197; // Convert from raw to m/s^2 - 4g
            double accel_x = raw_x * scale;
            double accel_y = raw_y * scale;
            double accel_z = raw_z * scale;

            printk("Acceleration (m/s^2): X=%.6f, Y=%.6f, Z=%.6f\n", accel_x, accel_y, accel_z);
        } else {
            printk("Failed to read raw data\n");
        }

        k_sleep(K_MSEC(300)); // Sleep for 500 milliseconds before reading again
    }
}

nrf52dk_nrf522832.overlay

&i2c0 {
    status = "okay";
    mysensor: ism330dhcx@6a {
        compatible = "st,ism330dhcx";
        reg = <0x6a>;
        label = "ISM330DHCX";
    };
};

prj.conf (I do not believe you need all in the list)

CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048

CONFIG_BT=y
CONFIG_LOG=y
CONFIG_BT_SMP=y
CONFIG_BT_SIGNING=y
CONFIG_BT_PERIPHERAL=y
CONFIG_BT_DIS=y
CONFIG_BT_ATT_PREPARE_COUNT=5
CONFIG_BT_BAS=y
CONFIG_BT_HRS=y
CONFIG_BT_IAS=y
CONFIG_BT_PRIVACY=n
CONFIG_BT_DEVICE_NAME="My_nRF52_Device"
CONFIG_BT_DEVICE_APPEARANCE=833
CONFIG_BT_DEVICE_NAME_DYNAMIC=y
CONFIG_BT_DEVICE_NAME_MAX=65

CONFIG_BT_KEYS_OVERWRITE_OLDEST=y
CONFIG_BT_SETTINGS=y
CONFIG_FLASH=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_FLASH_MAP=y
CONFIG_NVS=y
CONFIG_SETTINGS=y

CONFIG_BT_PERIPHERAL_PREF_MIN_INT=96
CONFIG_BT_PERIPHERAL_PREF_MAX_INT=96

CONFIG_GPIO=y  # Add this line for GPIO support

CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048

CONFIG_I2C=y
CONFIG_I2C_NRFX=y
CONFIG_SENSOR=y

CONFIG_ISM330DHCX=y

CONFIG_LOG=y
CONFIG_PRINTK=y
CONFIG_CBPRINTF_FP_SUPPORT=y

RE: Getting zeros from ISM330DHCX accelerometers

Kazi Afroza Sultana — Mon, 26 Aug 2024 15:20:57 GMT

Hello,

The default pin for i2C0 is SDA(26) and SCL (27) on nRf52832. Have you checked the pin set up?

There is an existing a driver for this sensor

https://github.com/nrfconnect/sdk-zephyr/tree/main/drivers/sensor/st/ism330dhcx; Is the sensor is correctly configured in your project's configuration file. The ISM330DHCX sensor should be enabled with CONFIG_ISM330DHCX=y.