Open-01-pcb

OPEN-01

OPEN-01 is an open-source, low-cost differential drive robot platform focused on embedded sensing, motion control, and autonomous navigation.

This repository contains the full stack:

• ESP-IDF firmware for the ESP32-S2 robot controller
• ROS2 serial bridge and bringup for Raspberry Pi 3B
• URDF robot description with STL meshes
• RViz2 visualization stack for the dev laptop
• robot_localization EKF for sensor fusion
• Linux setup scripts for both machines

What this repo is

OPEN-01 is designed as a low-cost, replicable alternative to the TurtleBot3. It is built around proven hardware and a clean layered architecture — embedded-first, with ROS2 as the autonomy layer on top.

The platform is structured around two compute nodes:

• ESP32-S2 — handles all real-time firmware: sensors, motors, odometry, and UART telemetry
• Raspberry Pi 3B — runs ROS2 Humble, bridges ESP32 telemetry to ROS2 topics, and relays lidar data
• Laptop — runs EKF, SLAM, Nav2, and RViz2 visualization over WiFi

Current capabilities

Firmware (ESP32-S2)

• Motor control — FIT0441 brushless DC motors, 25kHz PWM, encoder feedback, startup kick
• IMU — MPU6500 (WHO_AM_I=0x70), dedicated I2C bus, accel + gyro
• ToF ranging — 3x VL53L0X (left, right, back), XSHUT-based address assignment
• Odometry — wheel encoder integration, kinematics
• Battery monitoring — 3S Li-Ion voltage via ADC with voltage divider
• UART telemetry — custom binary protocol at 460800 baud with CRC16-CCITT

ROS2 Stack (Raspberry Pi 3B — ROS2 Humble)

• Serial bridge node — parses ESP32 binary protocol, publishes all sensor topics
• Lidar node — LDS-02 lidar via USB2LDS adapter, publishes /scan (in progress)
• robot_state_publisher — broadcasts full TF tree from URDF
• Systemd autostart — open01.service brings up the full stack on boot

ROS2 Stack (Laptop — ROS2 Jazzy)

• RViz2 visualization — CAD model, TF frames, odometry, lidar scan
• robot_localization EKF — fuses /odom + /imu/data → /odometry/filtered at 30Hz
• SLAM Toolbox — (planned)
• Nav2 — (planned)

Published ROS2 Topics

Hardware

Pin Map (ESP32-S2)

Repository structure

open-01/
├── robot_firmware/              # ESP32-S2 firmware (ESP-IDF v5.4)
│   └── main/
│       ├── config/              # GPIO, timing, robot geometry constants
│       ├── common/              # Shared robot state
│       ├── drivers/             # MPU6500, VL53L0X, motor drivers
│       ├── hal/                 # Hardware abstraction layer
│       ├── services/            # PID, kinematics, odometry, comms
│       └── tasks/               # FreeRTOS tasks (IMU, ToF, motor, comms)
├── robot_ros2/
│   └── ros2_ws/
│       └── src/
│           ├── open01_serial_bridge/   # ESP32 <-> ROS2 bridge + lidar node
│           ├── open01_bringup/         # RPi launch files
│           ├── open01_description/     # URDF + STL meshes
│           └── open01_viz/             # Laptop RViz2 launch + EKF config
├── cad/
│   └── URDFs/                   # SolidWorks URDF export (source)
├── scripts/
│   ├── setup_rpi.sh             # One-command RPi setup
│   └── setup_laptop.sh          # One-command laptop setup
├── tools/
│   ├── launcher.py              # ESP-IDF GUI launcher
│   └── setup.sh                 # ESP-IDF toolchain setup
├── LICENSE
└── README.md

Getting started

RPi setup (Ubuntu 22.04 + ROS2 Humble)

git clone https://github.com/RonishNadar/open-01.git
cd open-01
sudo bash scripts/setup_rpi.sh
sudo reboot

Laptop setup (Ubuntu 24.04 + ROS2 Jazzy)

git clone https://github.com/RonishNadar/open-01.git
cd open-01
sudo bash scripts/setup_laptop.sh
source ~/.bashrc

Firmware setup (ESP32-S2)

chmod +x tools/setup.sh
./tools/setup.sh
python3 tools/launcher.py

Running the robot

On RPi (auto-starts on boot via systemd)

sudo systemctl start open01.service
sudo systemctl status open01.service

Manual launch on RPi

cd ~/open-01/robot_ros2/ros2_ws
source install/setup.bash
ros2 launch open01_bringup bringup.launch.py

Visualization + EKF on laptop

cd ~/open-01/robot_ros2/ros2_ws
source install/setup.bash
ros2 launch open01_viz viz.launch.py

Verify topics

ros2 topic list
ros2 topic hz /odometry/filtered   # should be ~30Hz
ros2 topic hz /odom                # should be ~40Hz
ros2 topic hz /scan                # should be ~5Hz

Verify TF tree

ros2 run tf2_tools view_frames

Architecture

ESP32-S2 (firmware)
    |  UART 460800 baud (custom binary protocol, CRC16-CCITT)
    v
Raspberry Pi 3B (ROS2 Humble)
    |-- open01_serial_bridge  ->  /odom /imu/data /battery_state /tof/* /joint_states
    |-- lidar_node            ->  /scan
    |-- robot_state_publisher ->  /tf /tf_static
    |  WiFi (DDS, ROS_DOMAIN_ID=0)
    v
Laptop (ROS2 Jazzy)
    |-- robot_localization EKF  ->  /odometry/filtered
    |-- SLAM Toolbox            ->  /map (planned)
    |-- Nav2                    ->  autonomous navigation (planned)
    |-- RViz2                   ->  visualization

Firmware architecture

config/

Central constants: GPIO assignments, I2C/UART config, task periods, robot geometry, PID defaults.

common/

Shared robot state and data structures accessed across tasks.

drivers/

Low-level device drivers for MPU6500, VL53L0X, and motor control.

hal/

Hardware abstraction layer separating board-specific logic from services.

services/

Reusable robotics logic: PID, kinematics, odometry, motor coordination, UART comms.

tasks/

FreeRTOS task entry points for periodic runtime behavior. All tasks pinned to Core 0 (ESP32-S2 is single-core).

Key implementation notes

• ESP32-S2 ADC is 13-bit — ADC_BITWIDTH_DEFAULT, BATTERY_ADC_MAX = 8191.0f
• FIT0441 motors use inverted PWM (255=stop, 0=full speed), require 25kHz PWM and startup kick
• FG pins need 5kΩ external pull-up to 3.3V (open-collector output)
• VL53L0X requires full Pololu init sequence (SPAD calibration, 60+ tuning registers)
• LDS-02 checksum is (~sum(bytes[0:40])) & 0xFF, INDEX_MAX=0xDB
• Serial port on Ubuntu 22.04 RPi is /dev/ttyS0 (not /dev/ttyAMA0)
• ROS2 QoS — RPi nodes publish BEST_EFFORT, set RViz2 subscriptions to match
• EKF — IMU orientation not fused (MPU6500 has no magnetometer), only vyaw, ax, ay used from IMU

Project status

Firmware

• ESP-IDF firmware scaffold
• Shared robot state
• Motor control task + PID
• IMU task (MPU6500)
• ToF task (3x VL53L0X)
• Odometry + kinematics
• Battery monitoring
• UART comms task (custom binary protocol)
• Linux setup script + GUI launcher

ROS2

• Serial bridge node (ESP32 <-> ROS2)
• [~] LDS-02 lidar node (in progress — lidar bring-up)
• URDF robot description
• TF tree (all frames)
• RViz2 visualization
• Systemd autostart
• Setup scripts (RPi + laptop)
• robot_localization EKF (fusing /odom + /imu/data)
• SLAM Toolbox
• Nav2
• PID gain tuning

Documentation

• Hardware wiring guide
• Full system bring-up docs
• Demo videos

Contributing

Contributions are welcome. Good areas:

• hardware abstraction cleanup
• sensor validation and calibration
• motion control improvements
• Nav2 / SLAM configuration
• documentation and wiring diagrams
• testing utilities

When contributing:

1. keep modules focused
2. avoid hardcoding constants outside config.h
3. preserve the layered firmware structure
4. document any hardware assumptions clearly

License

Licensed under the Apache-2.0 License. See LICENSE for details.