ESP32 Forum

Posted: **Mon Oct 02, 2023 10:25 am**

Hello everyone.

I'm trying to read data from a component via I2C

From the documentation of said component, the address of the device is 0x6B and the register address is 0x30.

The data i want to read is the voltage of a battery but it's spread across two bytes with bit 15,14,13,0 being reserved (see attachment)

Thing is, I can't read the value i want (i get 0 for both the data bytes). I'm not sure what I'm doing wrong. I just want to make sure it's not the PCB that is faulty (i'm working with custom work in progress PCBs.

I'm using esp-idf 4.2 and I can not change to another version...

Here my driver setup :

Code: [Select all] [Expand/Collapse]

i2c_config_t conf;
conf.mode = I2C_MODE_MASTER;
conf.sda_io_num = SDA;
conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
conf.scl_io_num = SCL;
conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
conf.master.clk_speed = 500000;
i2c_param_config(I2C_NUM_0, &conf);
i2c_driver_install(I2C_NUM_0, conf.mode, 0, 0, 0);

GeSHi © Codebox Plus Extension

And here is my reading function :

Code: [Select all] [Expand/Collapse]

void CPowerManagement::BatteryCheckI2C()
{
    uint8_t data1;
    uint8_t data2;
    
    uint8_t reg= 0x30; 
    uint8_t address = 0x6B;
    uint16_t extracted_data;
    
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_WRITE, 1); 
    i2c_master_write_byte(cmd, reg, 1);
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_READ, 1);
    i2c_master_read_byte(cmd, &data1, I2C_MASTER_ACK);
    i2c_master_read_byte(cmd, &data2, I2C_MASTER_LAST_NACK);
    i2c_master_stop(cmd);
    i2c_master_cmd_begin(0, cmd, pdMS_TO_TICKS(3000));
    i2c_cmd_link_delete(cmd);
    
    
    // extracted_data = (data1 << 3) | (data2 >> 1); 
    ESP_LOGI(TAG, "Value read from I2C battery : %d et %d", data1, data2); // i get 0 and 0
}

ESP32 Forum

Read data with I2C communication

Read data with I2C communication