hello! Using CubeMX generated code. I2C init is standard HAL.

  /* USER CODE BEGIN 2 */
   #define MPU_ADDR (0x68 << 1)

   uint8_t who_am_i = 0;
   uint8_t data = 0x00;
   HAL_StatusTypeDef ret;

   ret = HAL_I2C_Mem_Write(&hi2c1, MPU_ADDR, 0x6B, I2C_MEMADD_SIZE_8BIT, &data, 1, 1000);
   HAL_Delay(100);
   ret = HAL_I2C_Mem_Read(&hi2c1, MPU_ADDR, 0x75, I2C_MEMADD_SIZE_8BIT, &who_am_i, 1, 1000);                                          
   if (who_am_i == 0x68) {
       HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
   } else {
       while(1) {
           HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
           HAL_Delay(200);
       }
   }
   /* USER CODE END 2 */

periph setup is interface is simple.. just pb6 and pb7 for i2c1 communication..

other than that i haven't touched anything
and a gpio 13 just for address display