ESP32 Forum

Posted: **Fri Mar 13, 2020 10:42 am**

I want to read/write bno055

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s8 BNO055_I2C_bus_write(u8 dev_addr, u8 reg_addr, u8 *reg_data, u8 cnt)
{
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (dev_addr << 1) | WRITE_BIT, ACK_CHECK_EN);
    i2c_master_write_byte(cmd, reg_addr, ACK_CHECK_EN);
    i2c_master_write_byte(cmd, *reg_data, ACK_CHECK_EN);
 
    i2c_master_stop(cmd);
 
    esp_err_t ret = i2c_master_cmd_begin(I2C_NUM_0, cmd, 1000 / portTICK_RATE_MS); //1000
    i2c_cmd_link_delete(cmd);
 
    ets_delay_us(10000);
 
    return ret;
}
 
s8 BNO055_I2C_bus_read(u8 dev_addr, u8 reg_addr, u8 *reg_data, u8 cnt)
{
    int ret;
    int i;
 
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
 
    //first - write a pointer to a register
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (dev_addr << 1) | WRITE_BIT, ACK_CHECK_EN);
    i2c_master_write_byte(cmd, reg_addr, ACK_CHECK_EN);
    i2c_master_stop(cmd);
 
    //second - read from the pointer
    ret = i2c_master_cmd_begin(I2C_NUM_0, cmd, 1000 / portTICK_RATE_MS);
    i2c_cmd_link_delete(cmd);
 
    //if (ret != ESP_OK)
        //return ret;
 
    cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, dev_addr << 1 | READ_BIT, ACK_CHECK_EN);
 
    if (cnt > 1)
    {
        for (i = 1; i < cnt; i++)
        {
            i2c_master_read_byte(cmd, reg_data, ACK_VAL);
            reg_data++;
        }
        i2c_master_read_byte(cmd, reg_data, NACK_VAL);
    }
    else
        i2c_master_read_byte(cmd, reg_data, NACK_VAL);
 
    i2c_master_stop(cmd);
 
    ret = i2c_master_cmd_begin(I2C_NUM_0, cmd, 1000 / portTICK_RATE_MS);  //1000
 
    i2c_cmd_link_delete(cmd);
 
    return ret;
}

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And I check

Code: [Select all] [Expand/Collapse]

BNO055_I2C_bus_read(BNO055_I2C_ADDR1, BNO055_CHIP_ID_REG, &val, 1);
printf("CHIP ID %X\n", val);

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But I have a wrong reading from the chip. May be I do something wrong in I2C read/write routines?

Posted: **Sat Mar 14, 2020 9:01 am**

The read should be a single command, not two separate ones. This is the code I'm using:

Code: Select all

/**
 * Read a block of data from an I2C device.
 * @param dev_id    I2C address of device
 * @param reg_addr  register number where read starts
 * @param reg_data  pointer to buffer where read data is stored
 * @param len       number of bytes to read
 * @return Zero for success, non-zero for error
 */
int8_t user_i2c_read(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
{
    if (len == 0) {
        return 0;
    }
    esp_err_t rslt = ESP_OK;
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (dev_id << 1) | I2C_MASTER_WRITE, ACK_CHECK_EN);
    i2c_master_write_byte(cmd, reg_addr, ACK_CHECK_EN);
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, (dev_id << 1) | I2C_MASTER_READ, ACK_CHECK_EN);
    if (len > 1) {
        i2c_master_read(cmd, reg_data, len - 1, I2C_MASTER_ACK);
    }
    i2c_master_read_byte(cmd, reg_data + len - 1, I2C_MASTER_NACK);
    i2c_master_stop(cmd);
    rslt = i2c_master_cmd_begin(I2C_NUM_0, cmd, pdMS_TO_TICKS(1000));
    if (rslt != ESP_OK) {
        ESP_LOGE(TAG, "Error on I2C read: (%x) %s ", rslt, esp_err_to_name(rslt));
    }
    i2c_cmd_link_delete(cmd);
    return rslt;
}

Posted: **Sun Mar 15, 2020 2:26 pm**

Thank you!

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