A fully featured 4-rotor drone with attitude stabilization, altitude hold, RC control, telemetry and safety features—all running on an Arduino Mega 2560.

1. Flight Controller: Arduino Mega 2560
2. Sensors:
   • MPU-6050 (6-axis IMU via I²C/DMP) → roll, pitch, yaw rates & angles
   • BMP280 (barometric pressure via I²C) → altitude
   • Optional HMC5883L magnetometer → heading
3. Actuators:
   • 4 × ESC-driven brushless motors (CW/CCW propellers)
4. RC Receiver: PWM input channels (roll, pitch, yaw, throttle)
5. Telemetry: UART → XBee or Bluetooth MOD
6. Power:
   • LiPo 3S (11.1 V)
   • 5 V BEC to Arduino & sensors

  Arduino Mega        MPU-6050           BMP280            RC Receiver
  ┌─────────────────┐ ┌───────┐         ┌───────┐         ┌─────────────────────┐
  │ 5 V    ──► VIN  │ │ VCC   │         │ VIN   │         │ Ch1 OUT ──► D44     │
  │ GND    ──► GND  │ │ GND   │         │ GND   │         │ Ch2 OUT ──► D45     │
  │ SDA    ──► 20   │ │ SDA   │◄────────│ SDA   │         │ Ch3 OUT ──► D46     │
  │ SCL    ──► 21   │ │ SCL   │◄────────│ SCL   │         │ Ch4 OUT ──► D47     │
  │ INT    ──► 2    │ └───────┘         └───────┘         └─────────────────────┘
  └─────────────────┘

  Arduino Mega        ESC Outputs         Motors (CW/CCW)
  ┌─────────────────┐ ┌─────────────────┐ ┌───────────────────────────┐
  │ D6      ──► ESC1│─►│ PWM Out 1 ──►  │ M1 CW   │ Front-Left        │
  │ D7      ──► ESC2├─►│ PWM Out 2 ──►  │ M2 CCW  │ Front-Right       │
  │ D8      ──► ESC3│─►│ PWM Out 3 ──►  │ M3 CW   │ Rear-Right        │
  │ D9      ──► ESC4│─►│ PWM Out 4 ──►  │ M4 CCW  │ Rear-Left         │
  └─────────────────┘ └─────────────────┘ └───────────────────────────┘

• ESC PWM: standard 400 Hz PWM (0–2000 µs pulse) on D6–D9.
• RC Inputs: pulseIn on D44–D47 (roll, pitch, throttle, yaw).
• I²C Bus: SDA on 20, SCL on 21, pull-ups already on Mega.

1. Initialization

   • Wake up MPU-6050 DMP for angle estimation
   • Calibrate zero-offsets for gyro & barometer

2. RC Channel Mapping

   • Read raw PWM from receiver (1000–2000 µs)
   • Map to desired setpoints:
     • RollSet = (rollPWM − 1500) / 500 → ±1.0
     • PitchSet = …
     • YawSet = (yawPWM − 1500) / 500 → ±1.0
     • Throttle = (thPWM − 1000) / 1000 → [0…1]

3. Sensor Feedback

   • Get pitchAngle & rollAngle from DMP
   • Get yawRate from gyro (for heading control)
   • Get altitude from BMP280 → altitude error

4. PID Controllers

   • PID_roll on (RollSet, rollAngle) → corrRoll
   • PID_pitch on (PitchSet, pitchAngle) → corrPitch
   • PID_yaw on (YawSet, gyroYawRate) → corrYaw
   • PID_alt on (ThrottleSet, altitude) → corrAlt

5. Motor Mixing

   Motor mixing equations
   M1 = baseThr + corrPitch + corrRoll - corrYaw;
   M2 = baseThr + corrPitch - corrRoll + corrYaw;
   M3 = baseThr - corrPitch - corrRoll - corrYaw;
   M4 = baseThr - corrPitch + corrRoll + corrYaw;
   

6. Safety

• Cut motors if tilt > 60° or RC signal lost
• Failsafe throttle drop

1. Arduino IDE Libraries

• Wire (built-in)
• MPU6050 & I2Cdev (Jeff Rowberg)
• Adafruit_BMP280 (Adafruit)
• PID_v1 (Brett Beauregard)

2. Create folder QuadPro/ with:

• README.md (this file)
• QuadPro.ino (sketch below)

3. Open QuadPro.ino in IDE, select Arduino Mega 2560, set COM port

1. Idle Setup

• Propellers off; power on and let it sit to zero sensors
• Check RC failsafe & arm sequence (e.g. throttle low + yaw right)

2. PID Tuning (one axis at a time):

• Increase Kp until small oscillations on axis
• Add Ki to correct drift
• Add Kd to damp overshoot

3. Hover Test at low altitude (1 m indoors)
4. Altitude Hold tuning with barometer
5. Flight Tests: gentle
6. Failsafe Tests: signal loss, tilt shutdown

Refine gains and mixes incrementally. Enjoy your professional drone!