ROSArduinoBridge – Autonomous Mobile Robot Firmware

This repository contains the Low-Level Control Unit firmware developed for differential drive autonomous mobile robots.
Designed to run on the Arduino Mega 2560, this firmware acts as a bridge between the robot hardware and the ROS 2 (Robot Operating System) navigation stack via serial communication.

This project was developed as part of an autonomous vehicle platform that achieved
🥈 2nd Place in Turkey – TEKNOFEST 2025 Industrial Digital Technologies Competition.

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📌 Project Overview

The firmware manages the robot’s actuators (DC motors, servo motors) and sensors (quadrature encoders, battery voltage monitoring, emergency stop).
It communicates with a high-level computer (Raspberry Pi 4) running ROS 2 and provides:

• Real-time PID speed control
• Encoder-based odometry data streaming
• Peripheral and safety management

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✨ Key Features

• ROS 2 Integration
  Optimized serial communication protocol compatible with ros2_control and hardware_interface architectures.

• Advanced PID Control
  Closed-loop speed control customized for 1000 RPM DC motors.

• Modular Driver Architecture
  Isolated driver layers for:

  • BTS7960 high-current motor drivers
  • Quadrature encoders

• Safety Protocols

  • Hardware Emergency Stop (E-Stop)
  • Automatic motor stop on communication loss

• Peripheral Management

  • DFPlayer Mini–based audio feedback
  • Servo motor control
  • Battery voltage and percentage monitoring

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🧩 Hardware Architecture

Component	Description
Microcontroller	Arduino Mega 2560
Host Computer (SBC)	Raspberry Pi 4 (ROS 2 Host)
Motor Driver	BTS7960 High Power Motor Driver
Motors	1000 RPM DC Motors with Quadrature Encoders
Audio System	DFPlayer Mini (UART)
Power Management	Voltage divider for 3S–4S LiPo/Li-ion monitoring

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🔌 Pin Configuration

Default pin assignments defined in ROSArduinoBridge.ino and related headers:

Component	Function	Pin (Mega 2560)	Notes
Left Motor	PWM Fwd (LPWM)	9	BTS7960
	PWM Rev (RPWM)	6	BTS7960
Right Motor	PWM Fwd (LPWM)	11	BTS7960
	PWM Rev (RPWM)	10	BTS7960
Left Encoder	Channel A	2	Interrupt
	Channel B	3	Interrupt
Right Encoder	Channel A	18	Interrupt
	Channel B	19	Interrupt
Audio (DFPlayer)	RX (SoftSerial)	12	To DFPlayer TX
	TX (SoftSerial)	13	To DFPlayer RX
Servo	PWM Signal	4	Mechanism control
Safety	Emergency Stop	14	Pull-up input
Signal	Buzzer	8	Audio warning
Battery	Voltage Read	A0	Voltage divider

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⚙️ Installation & Setup

Prerequisites

• Arduino IDE 1.8.x or newer
• DFRobotDFPlayerMini library
  (Install via Arduino Library Manager)

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Configuration

1. Open ROSArduinoBridge.ino
2. Ensure the BAUDRATE matches your ROS 2 configuration
   • Default: 57600
3. Tune PID coefficients in diff_controller.h:

   Kp, Ki, Kd

according to your mechanical system.

Upload

• Select Arduino Mega 2560 as the target board

• Compile and upload the firmware

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🧪 System Testing & Verification

Before launching ROS 2 nodes, it is strongly recommended to verify hardware and firmware via a direct serial connection.

Step 1: Connection

Connect the Arduino to the Raspberry Pi via USB. Ensure the device is available at:

/dev/ttyACM0 

Step 2: Launch Serial Terminal

python3 -m serial.tools.miniterm /dev/ttyACM0 57600

Step 3: Command Testing

Press Enter after each command.

▶ Motor Test

m 120 120

Expected: Both wheels rotate forward.

⏹ Stop Motors

m 0 0

🔄 Read Encoders

e

Expected Output Example:

1250 1250

🔁 Serial Communication Protocol

A lightweight, single-character command structure is used to minimize communication overhead.

Command	Description
m <L> <R>	Set motor speeds (ticks/loop)
e	Read encoder values
r	Reset encoders and PID state
u <Kp>:<Kd>:<Ki>:<Ko>	Update PID coefficients
`b <1	0>`
s <index>	Play audio file
v <index>	Trigger servo (90° → wait 5s → return)
f	Read battery voltage and percentage

📄 License

This project is licensed under the MIT License.

🏁 Notes

This firmware was developed for TEKNOFEST 2025 and represents ongoing R&D work in autonomous systems and industrial robotics.

Developed and maintained by Adil NAS with Yigido Team