const int ledBluePin = 5;
const int ledRedPin = 6;
const int ledGreenPin = 4;

#include<Wire.h>
const int MPU_addr=0x68;  // I2C address of the MPU-6050
float accx, accy, accz;
uint8_t state = 0;
uint8_t prev_state = 0;

void setup(){
  Wire.begin();
  Wire.beginTransmission(MPU_addr);
  Wire.write(0x6B);  // PWR_MGMT_1 register
  Wire.write(0);     // set to zero (wakes up the MPU-6050)
  Wire.endTransmission(true);
  Serial.begin(9600);
  
  pinMode(ledRedPin, OUTPUT);
  pinMode(ledGreenPin, OUTPUT);
  pinMode(ledBluePin, OUTPUT);

  analogWrite(ledRedPin, 255);
  analogWrite(ledGreenPin, 255);
  analogWrite(ledBluePin, 255);
}

void loop(){
  Wire.beginTransmission(MPU_addr);
  Wire.write(0x3B);  // starting with register 0x3B (ACCEL_XOUT_H)
  Wire.endTransmission(false);
  Wire.requestFrom(MPU_addr,14,true);  // request a total of 14 registers
  accx=(Wire.read()<<8|Wire.read()) / 16384.0;  // 0x3B (ACCEL_XOUT_H) & 0x3C (ACCEL_XOUT_L)    
  accy=(Wire.read()<<8|Wire.read()) / 16384.0;  // 0x3D (ACCEL_YOUT_H) & 0x3E (ACCEL_YOUT_L)
  accz=(Wire.read()<<8|Wire.read()) / 16384.0;  // 0x3F (ACCEL_ZOUT_H) & 0x40 (ACCEL_ZOUT_L)

  if (accx < 1.0 && accy < 1.0) { // red = z axis downwards
    analogWrite(ledRedPin, 0);
    analogWrite(ledGreenPin, 255);
    analogWrite(ledBluePin, 255);
  }
  else if (accz < 1.0 && accy < 1.0) { // green = x axis downwards
    analogWrite(ledRedPin, 255);
    analogWrite(ledGreenPin, 0);
    analogWrite(ledBluePin, 255);
  }
  else if (accx < 1.0 && accz < 1.0) { // blue = y axis downwards
    analogWrite(ledRedPin, 255);
    analogWrite(ledGreenPin, 255);
    analogWrite(ledBluePin, 0);
  }

  Serial.print("AcX = "); Serial.print(accx);
  Serial.print(" | AcY = "); Serial.print(accy);
  Serial.print(" | AcZ = "); Serial.println(accz);
}