MPU6050 not responding on address 0x68 but shows up in I2C Scanned addresses

Question

When i run the I2C scanner on STM32F303, i see both devices connected to the bus. Names a device on address 0x3C (OLED) and address (0x68) MPU6050. Both addresses, specifically agree with what the datasheet says.

However, when i try to read the WHO_AM_I register on address 0x68 using HAL_I2C_IsDeviceReady, i realize that it even times out.

int main(void)
{
    HAL_Init();
    SystemClock_Config();

    MX_GPIO_Init();
    MX_I2C1_Init();
    MX_SPI1_Init();
    MX_TIM6_Init();
    MX_USART1_UART_Init();

    I2C_Scanner();
    SSD1306_Init();

    HAL_Delay (2000);

    MPU6050_Init();

    while (1)
    {

    }
}

Function (MPU6050_Init) to check if the device is ready

static void MPU6050_Init(void)
{
    HAL_Delay(1);
    SSD1306_Clear();
    SSD1306_GotoXY (0, 0);
    char OutputArray[50] = {0};

    if(HAL_I2C_IsDeviceReady(&hi2c1, MPU6050_I2C_ADDR, 10, HAL_MAX_DELAY) != HAL_OK)
    {
        sprintf(OutputArray, "0x%02x : Not ready", MPU6050_I2C_ADDR);
    }
    else
    {
        HAL_GPIO_WritePin(LD3_GPIO_Port, LD3_Pin, GPIO_PIN_SET);

        uint8_t check;

        HAL_I2C_Mem_Read(&hi2c1, MPU6050_I2C_ADDR, WHO_AM_I_REG, 1, &check, 1, HAL_MAX_DELAY);

        sprintf(OutputArray,"0x%02x", (uint16_t)check);
    }
    HAL_Delay(1);
    SSD1306_Puts (OutputArray, &Font_7x10, SSD1306_COLOR_WHITE);
    SSD1306_UpdateScreen();
}

Function (I2C_Scanner) to scan for I2C bus for available devices

static void I2C_Scanner(void)
{
    HAL_StatusTypeDef result;
    uint8_t i;
    for (i = 1; i < 128; i++)
    {
        result = HAL_I2C_IsDeviceReady(&hi2c1, (uint16_t)(i << 1), 1, HAL_MAX_DELAY);
        char* period = ".";
        char OutputArray[5];

        if (result != HAL_OK) // HAL_ERROR or HAL_BUSY or HAL_TIMEOUT
        {
              HAL_UART_Transmit(&huart1, (uint8_t*)period, sizeof(period), HAL_MAX_DELAY);
        }

        if (result == HAL_OK)
        {
            sprintf(OutputArray, "0x%02x", i); // Received an ACK at that address
            HAL_UART_Transmit(&huart1, (uint8_t*)OutputArray, sizeof(OutputArray), HAL_MAX_DELAY);
        }

        HAL_Delay(1);
    }
}

Function (MC_I2C1_Init) to initialize the I2C

static void MX_I2C1_Init(void)
{
    hi2c1.Instance = I2C1;
    hi2c1.Init.Timing = 0x0000020B;
    hi2c1.Init.OwnAddress1 = 0;
    hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
    hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
    hi2c1.Init.OwnAddress2 = 0;
    hi2c1.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
    hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
    hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;

    if (HAL_I2C_Init(&hi2c1) != HAL_OK)
    {
        Error_Handler();
    }

    if (HAL_I2CEx_ConfigAnalogFilter(&hi2c1, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
    {
        Error_Handler();
    }

    if (HAL_I2CEx_ConfigDigitalFilter(&hi2c1, 0) != HAL_OK)
    {
        Error_Handler();
    }
}

The expected results would be to check that the device is available, ready and convey back the contents of the WHO_AM_I register

Hakim Marley Hakim Marley · Accepted Answer · 2019-11-06T16:15:33

Found a solution. The problem was that i had defined the MPU6050 address as follows

#define MPU6050_I2C_ADDR    0x68

The correct definition should have been

#define MPU6050_I2C_ADDR    0x68 << 1

Which resulted in 0xD0

MPU6050 not responding on address 0x68 but shows up in I2C Scanned addresses

1 Answers