Communication with a sensor not in the driver database with I2C on nRF52840 DK Zephyr.

Question

Hi everyone,

I started to develop an application on the nRF52840 DK in Visual Studio Code and I have trouble to communicate with my sensor via I2C.

The major issue is that i'm a newbie in Zephyr and the sensor i selected isn't quite popular so there isn't a lot of documentation online and no drivers available in the Zephyr driver database.

I use the LSM6DSV16X by STm, I've at first tested the sensor on arduino with the example provided by STm and it worked.

I tried to communicate via the sensor directly without drivers but I have trouble understanding the i2c_write and i2c_read function on Zephyr. If i understand well i don't need to change anything in the devicetree since i'm not using drivers. Is that correct ?

Here is my main :

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/kernel.h>
#include <zephyr/drivers/i2c.h>
#include <zephyr/drivers/gpio.h>


/* 1000 msec = 1 sec */
#define SLEEP_TIME_MS   1000

#define LSM16_I2C_ADD 0x6B // I2c adress according to datasheet
#define LSM16_ACC_L_X 0x28 // 8-bit register that store the Low part of the acceleration following X axe.
#define LSM16_ACC_H_X 0x29 // 8-bit register that store the High part of the acceleration following X axe.



#define I2C_NODE DT_NODELABEL(i2c0)

static const struct device *i2c_Mydevice = DEVICE_DT_GET(I2C_NODE);

static uint8_t i2c_buffer[2] = {};

// function to combine the High and low register of my sensor

uint16_t combineRegister(uint8_t upperBytes, uint8_t lowerBytes); 


void main(void)
{
	
	int error;
	uint16_t accx = 10;
	if(!device_is_ready(i2c_Mydevice))
	{
		printk("I2C_device not ready\n");
		return;
	}
	 

	while (1) {
		i2c_buffer[0] =	LSM16_ACC_L_X  ; 
		
		i2c_buffer[1] =	LSM16_ACC_H_X  ;
		
		do
		{
			
			// Test de d'écriture du bus I2C
			error = i2c_write(i2c_Mydevice, i2c_buffer, 1, LSM16_I2C_ADD);			
			if (error<0)
				{printk("LSM16 write failure : %d\n", error); break;}
			

			// Test de lecture du bus I2C
			error = i2c_read(i2c_Mydevice, i2c_buffer , 1 , LSM16_I2C_ADD);
			if (error<0)
				{printk("LSM16 read failure : %d\n", error); break;}

			accx = combineRegister(i2c_buffer[0], i2c_buffer[1]);
			
			printk("Value of Accx = %d\n", accx);

					

		} while (false);
			
		k_msleep(SLEEP_TIME_MS);
	}

}

// function to combine the High and low register of my sensor

uint16_t combineRegister(uint8_t upperBytes, uint8_t lowerBytes)
{
	uint16_t accX_combined = 0;
    printk(" valeur de upper %d valeur de lower %d \n", upperBytes, lowerBytes);
	accX_combined = upperBytes << 8 | lowerBytes; 
	
	return accX_combined;
}

I've enable the I2C in the prj.conf file and included the driver for I2C in my main code but I'm stuck. I think I managed to communicate with my sensor since this :

error = i2c_write(i2c_Mydevice, i2c_buffer, 1, LSM16_I2C_ADD);

if (error<0)

{printk("LSM16 write failure : %d\n", error); break;}

doesn't provide me error when my sensor is connected.

prj.conf code :

CONFIG_GPIO=y
CONFIG_I2C=y
CONFIG_CBPRINTF_FP_SUPPORT=y

So I have the following questions :

- Do I need to use the standard 'C' driver library provided by STm avaible here https://github.com/STMicroelectronics/STMems_Standard_C_drivers/tree/master/lsm6dsv16x_STdC in order to simply get data from the registers of my sensor. Or can I get those data via the standard function in Zephyr

- If I need to use drivers how do I add them to zephyr ?

Hope my issue isn't to trivial but I'm really stuck and I can't find anything on the web :(.

Thanks in advance

Best regards.

Communication with a sensor not in the driver database with I2C on nRF52840 DK Zephyr.

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