static void initMPU(void)
{
    uint8_t error, c;
    
    Wire.begin();
    c = mpu.readWho(&error);
    Serial.print("WHO_AM_I : ");
    Serial.print(c,HEX);
    Serial.print(", error = ");
    Serial.println(error,DEC);

    c = mpu.readSleepBit(&error);
    Serial.print("PWR_MGMT_1 : ");
    Serial.print(c,HEX);
    Serial.print(", error = ");
    Serial.println(error,DEC);
    
    mpu.writeAccelFullScaleRange(16, NULL);

    mpu.writeSleepBit(0, &error);
    Serial.print("PWR_MGMT_1 write : error = ");
    Serial.println(error,DEC);
}