How to use I2C to read/write register with 10-bit register address?

[snowuyl]

Describe the bug
I try to read/write registers of TI LP5861 through I2C interface. But it failed with error code -5. Does Zephyr project provide sample code to read register with 10-bit register address ?
Expected behavior
Can reading/writing registers of TI LP5861 through I2C successfully.

Logs and console output
00> *** Booting Zephyr OS build v3.3.99-ncs1-1 ***
00> Starting button Test example
00> device_is_ready() ok
00> nrfx_gpiote_input_configure() okay for button
00> val=1
00> button released
00> start a timer
00> now-1-11-30 0:0:0
00> 0
00> ledDriverInit
00> tca6424aReadReg(regAddr=0x0)
00> LP5861_REG_ADDR_HIGH(regAddr)=0x0, LP5861_REG_ADDR_LOW(regAddr)=0x0
00> devAddr=0x81, startAddr=0x0
00> [00:00:00.501,129] i2c_nrfx_twim: Error on I2C line occurred for message 0
00> i2c_burst_read(0x0) failed, ret=-5
00> _buttonTimerHandler: 3000
00> now-1-11-30 0:0:0
00> button released

Environment (please complete the following information):

• OS: Windows 11
• Toolchain: Zephyr OS build v3.3.99-ncs1-1

[snowuyl]

[snowuyl]

LP5861.pdf

[Prasanna1717]

Hello,
I wrote a code for reading and writing to a register using Zephyr's i2c API. It's my old sample code, please feel free to use it for a test case and let me know.
Please replace "I2C_1" with the name of your specific I2C controller and 0xABC with the actual 10-bit address of your LP5861 device.I guess, It should solve your bug.

CODE,
#include <zephyr.h>
#include <device.h>
#include <drivers/i2c.h>
#include <stdio.h>

#define I2C_DEV_NAME "I2C_1" // Replace with your I2C controller's name
#define LP5861_10BIT_ADDR 0xABC // Replace with your LP5861's 10-bit address

void main(void) {
struct device *i2c_dev;
uint8_t data_to_write = 0x34; // Data to write to the register
uint8_t read_data; // Data read from the register
uint8_t register_address = 0xAB; // Replace with the actual register address
struct i2c_msg msgs[2];

// Open the I2C device
i2c_dev = device_get_binding(I2C_DEV_NAME);
if (!i2c_dev) {
    printk("I2C device not found\n");
    return;
}

// Prepare the write message
msgs[0].buf = &data_to_write;
msgs[0].len = sizeof(data_to_write);
msgs[0].flags = I2C_MSG_WRITE;

// Prepare the read message
msgs[1].buf = &read_data;
msgs[1].len = sizeof(read_data);
msgs[1].flags = I2C_MSG_READ | I2C_MSG_STOP;

// Start the I2C communication
int ret = i2c_transfer(i2c_dev, &msgs[0], 1, LP5861_10BIT_ADDR);
if (ret) {
    printk("Error writing to register: %d\n", ret);
    return;
}

// Delay (if needed) to ensure the write operation has taken effect

// Start the I2C communication for read
ret = i2c_transfer(i2c_dev, &msgs[1], 1, LP5861_10BIT_ADDR);
if (ret) {
    printk("Error reading from register: %d\n", ret);
    return;
}

// Print the read data
printk("Read data from register: 0x%02X\n", read_data);

}

Regards
Prasanna

[ndrs-pst]

@snowuyl, I hope you've managed to solve your issue.

For anyone working on projects that require 10-bit addressing in I2C, here's some helpful information.

---

To effectively experiment with I2C drivers, make sure to enable CONFIG_I2C_SHELL=y and use i2c command in console.

When dealing with 10-bit register addresses, setting I2C_MSG_ADDR_10_BITS is crucial.
This is accomplished by calling i2c_configure(). The code snippet provided below illustrates the process:

int ret;
uint32_t dev_config = 0;

ret = i2c_get_config(dev, &dev_config);
dev_config |= I2C_MSG_ADDR_10_BITS;          /* Enabling the 10-bit address mode */
ret = i2c_configure(dev, dev_config);        /* Configuring the device with the new setting */

[stichkule]

@snowuyl Not sure if you're issue is resolved, but looking at that I2C spec for LP5861, it doesn't look like 10-bit addressing. For 10-bit addressing, the first byte MUST contain 0b11110XX (XX represents 2 bits from the slave address). Followed by the remaining 8 bits of the slave address in the second byte.

See https://www.totalphase.com/support/articles/200349176-7-bit-8-bit-and-10-bit-i2c-slave-addressing/#10bit