Serial Parser

This repository provides a ROS 2 node to interact with serial ports. It is designed to read data from a serial port, parse it, and publish structured messages in ROS 2. Additionally, it can listen to a specific ROS topic and write the data to the same serial port.

It contains a single ROS2 node: serial_parser. It takes the following ROS params:

• port: The serial port to read from (e.g., /dev/ttyUSB0).
• baudrate: The baud rate for the serial communication (default is 115200).
• listen_to_topic: The ROS topic to listen to. When receiving a message on this topic, the node will write the data to the serial port.
• publish_topic: The ROS topic to publish the parsed data received from the serial port.
• poll_rate: The rate at which the node polls the serial port for new data (default is 10 Hz).

Dependencies

The driver has been tested with the following set up:

• ROS 2 Humble
• Ubuntu 22.04 LTS
• Python 3.10.12
• pyserial

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Installation

Clone the repository into your ROS 2 workspace and build the packages:

cd ~/ros2_ws/src
git clone https://github.com/smarc-project/serial_parser.git
colcon build && source install/setup.bash

Usage

1. Launch file

The easiest option to run the driver is using the launch file in serial_parser package:

ros2 launch serial_parser test.launch

2. Run the node manually

ros2 run serial_parser serial_parser --ros-args \
  -p port:="/dev/pts/4" \
  -p baudrate:=115200 \
  -p listen_to_topic:="serial_input" \
  -p publish_topic:="serial_output"

Testing

The serial_parser node can be tested by simulating a virtual serial connection:

1. Start a virtual serial port using socat:

socat -d -d pty,raw,echo=0 pty,raw,echo=0

Note the output, which will show two virtual serial ports (e.g., /dev/pts/3 and /dev/pts/4).

2. In another terminal, start the serial_parser node, listen to the second virtual port:

ros2 run serial_parser serial_parser --ros-args \
  -p port:="/dev/pts/4" \
  -p baudrate:=115200 \
  -p listen_to_topic:="serial_input" \
  -p publish_topic:="serial_output"

3. In another terminal, run test/test_virtual_serial_connection.py to send data to the first virtual port:

python3 test/test_virtual_serial_connection.py --port="/dev/pts/3" --baudrate=115200

4. You can send messages to the listen_to_topic by running:

ros2 topic pub /listen_to_topic std_msgs/msg/String "data: 'Hello, Serial!'"

5. You can check the messages published on the publish_to_topic by running:

ros2 topic echo /publish_to_topic