porter_esp32_bridge

Porter ESP32 Bridge

ROS 2 Jazzy bridge nodes for communicating with ESP32 microcontrollers over USB serial using the Porter binary protocol.

Nodes

esp32_motor_bridge

Bridges ROS 2 /cmd_vel (Twist) to ESP32 #1 motor controller.

• Subscribes: /cmd_vel (geometry_msgs/Twist)
• Publishes: /motor_status (std_msgs/String), /diagnostics
• Converts (linear.x, angular.z) → differential drive (left_speed, right_speed)
• Sends periodic heartbeat to ESP32; ESP32 stops motors if heartbeat lost
• Watchdog: stops motors if no /cmd_vel for cmd_vel_timeout seconds

esp32_sensor_bridge

Bridges ESP32 #2 fused sensor data to ROS 2.

• Publishes: /environment (sensor_msgs/Range), /sensor_status (std_msgs/String), /diagnostics
• Receives fused obstacle distance (ToF + Ultrasonic + Microwave Kalman filter)
• Polls ESP32 for per-sensor health status

Parameters

See config/esp32_bridge_params.yaml for all parameters with descriptions.

Protocol

Uses the Porter binary protocol (esp32_firmware/common/):

• Wire format: [0xAA 0x55][Length][Command][Payload...][CRC16]
• CRC16-CCITT (poly 0x1021, init 0xFFFF)
• Shared C library linked into both the ESP32 firmware and this ROS 2 package

Launch

ros2 launch porter_esp32_bridge esp32_bridge_launch.py
ros2 launch porter_esp32_bridge esp32_bridge_launch.py motor_port:=/dev/ttyUSB0 sensor_port:=/dev/ttyUSB1

Prerequisites

• ESP32 devices connected via USB serial
• udev rules installed for stable device names (see esp32_firmware/udev/)