#define I2C_ACCELEROMETER_ADDRESS 0xD0 //( 0x68 + one bit)
      #define I2C_OWN_ADDRESS 0x72

//Init I2C communication to accelerometer
    // enable I2C0 clock
    rcu_periph_clock_enable(RCU_I2C0);
    // connect PB8 to I2C0_SCL
    gpio_af_set(GPIOB, GPIO_AF_1, GPIO_PIN_8);
    // connect PB9 to I2C0_SDA
    gpio_af_set(GPIOB, GPIO_AF_1, GPIO_PIN_9);
    gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_PULLUP,GPIO_PIN_8);
    gpio_output_options_set(GPIOB, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ,GPIO_PIN_8);
    gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_PULLUP,GPIO_PIN_9);
    gpio_output_options_set(GPIOB, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ,GPIO_PIN_9);

void I2C_Accelerometer_init(void){
        // configure I2C0 clock
        i2c_clock_config(I2C0, 100000, I2C_DTCY_2);
        // configure I2C0 address
        i2c_mode_addr_config(I2C0, I2C_I2CMODE_ENABLE, I2C_ADDFORMAT_7BITS, I2C_OWN_ADDRESS);
        // enable I2C0
        i2c_enable(I2C0);
        // enable acknowledge
        i2c_ack_config(I2C0, I2C_ACK_ENABLE);
    }

extern uint8_t Accelerometer_X_High;

    //periodically called by timers in it.c
    void GetAccelerometerData(void){
        uint8_t bytesToReadIndex=0;

        //WAKE UP ACCELEROMETER (6B 00)

        // wait until I2C bus is idle
      while(i2c_flag_get(I2C0, I2C_FLAG_I2CBSY));
      // send a start condition to I2C bus
      i2c_start_on_bus(I2C0);

        // wait until SBSEND bit is set
      while(!i2c_flag_get(I2C0, I2C_FLAG_SBSEND));

        // send slave address to I2C bus
      i2c_master_addressing(I2C0, I2C_ACCELEROMETER_ADDRESS, I2C_TRANSMITTER);

        // wait until ADDSEND bit is set
      while(!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND));

      // clear ADDSEND bit
      i2c_flag_clear(I2C0, I2C_FLAG_ADDSEND);

    // send a data byte
      i2c_data_transmit(I2C0,0x6B);  //PWR MANAGEMENT
      // wait until the transmission data register is empty
      while(!i2c_flag_get(I2C0, I2C_FLAG_TBE));
        // send a data byte
      i2c_data_transmit(I2C0,0x00);  //WAKE UP
        // wait until the transmission data register is empty
      while(!i2c_flag_get(I2C0, I2C_FLAG_TBE));

    // send a stop condition to I2C bus
      i2c_stop_on_bus(I2C0);


      while(I2C_CTL0(I2C0)&0x0200);


        //REQUEST ACELEROMETER DATA (3B )

        // wait until I2C bus is idle
      while(i2c_flag_get(I2C0, I2C_FLAG_I2CBSY));
      // send a start condition to I2C bus
      i2c_start_on_bus(I2C0);

        // wait until SBSEND bit is set
      while(!i2c_flag_get(I2C0, I2C_FLAG_SBSEND));

        // send slave address to I2C bus
      i2c_master_addressing(I2C0, I2C_ACCELEROMETER_ADDRESS, I2C_TRANSMITTER);

        // wait until ADDSEND bit is set
      while(!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND));
      // clear ADDSEND bit
      i2c_flag_clear(I2C0, I2C_FLAG_ADDSEND);

    // send a data byte
      i2c_data_transmit(I2C0,0x3B);  //ACCELEROMETER REGISTER
      // wait until the transmission data register is empty
      while(!i2c_flag_get(I2C0, I2C_FLAG_TBE));


    // send a stop condition to I2C bus
      i2c_stop_on_bus(I2C0);


      while(I2C_CTL0(I2C0)&0x0200);




        //now reopen the bus to receive the reply



        // wait until I2C bus is idle
      while(i2c_flag_get(I2C0, I2C_FLAG_I2CBSY));
      // send a start condition to I2C bus
      i2c_start_on_bus(I2C0);
      // wait until SBSEND bit is set
      while(!i2c_flag_get(I2C0, I2C_FLAG_SBSEND));
      // send slave address to I2C bus
      i2c_master_addressing(I2C0, I2C_ACCELEROMETER_ADDRESS, I2C_RECEIVER);
        // wait until ADDSEND bit is set
      while(!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND));

        // if we receive only one byte: reset ACKEN bit
      i2c_ack_config(I2C0, I2C_ACK_DISABLE);

      //clear ADDSEND bit
      i2c_flag_clear(I2C0, I2C_FLAG_ADDSEND);

      // if we receive only one byte: send stop condition
      i2c_stop_on_bus(I2C0);


      /* wait until the RBNE bit is set */
      while(!i2c_flag_get(I2C0, I2C_FLAG_RBNE));
      //read a data from I2C_DATA
      Accelerometer_X_High = i2c_data_receive(I2C0);

      // if we receive more bytes: send a stop condition to I2C bus
      //i2c_stop_on_bus(I2C0);
      while(I2C_CTL0(I2C0)&0x0200);
      // enable acknowledge
      i2c_ack_config(I2C0, I2C_ACK_ENABLE);

    }