Initial (untested) code for a lidar ros node.

Author: bertrik

ros_ws/src/lidar/lidar/lidar_node.py

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+#!/usr/bin/env python3
+# Copyright 2025 Bertrik Sikken <bertrik@sikken.nl>
+import threading
+from enum import Enum
+
+import rclpy
+import serial
+from rclpy.node import Node
+from sensor_msgs.msg import LaserScan
+
+
+class FrameExtractor:
+    class State(Enum):
+        HEADER_1 = 1
+        HEADER_2 = 2
+        COLLECT = 3
+
+    def __init__(self) -> None:
+        self.state = self.State.HEADER_1
+        self.index = 0
+        self.length = 0
+        self.data = bytearray(60)
+
+    def add_data(self, b):
+        self.data[self.index] = b
+        self.index = self.index + 1
+
+    def process(self, b):
+        """ processes one byte, returns True if a full frame was received """
+        match self.state:
+            case self.State.HEADER_1:
+                self.index = 0
+                if b == 0x55:
+                    self.add_data(b)
+                    self.state = self.State.HEADER_2
+
+            case self.State.HEADER_2:
+                if b == 0xAA:
+                    self.add_data(b)
+                    self.length = len(self.data)
+                    self.state = self.State.COLLECT
+                else:
+                    self.state = self.State.HEADER_1
+                    self.process(b)
+
+            case self.State.COLLECT:
+                if self.index < self.length:
+                    self.add_data(b)
+                if self.index == self.length:
+                    # done
+                    self.state = self.State.HEADER_1
+                    return True
+        return False
+
+    def get_data(self):
+        return self.data
+
+
+class MysteryLidar:
+    def __init__(self, device):
+        self.serial = serial.Serial(device, baudrate=230400, timeout=0.1)
+        self.extractor = FrameExtractor()
+
+    def open(self) -> None:
+        self.serial.open()
+
+    def poll(self) -> bytes | None:
+        num = self.serial.in_waiting
+        while num > 0:
+            num = num - 1
+            b = self.serial.read()
+            done = self.extractor.process(b)
+            if done:
+                return self.extractor.get_data()
+        return None
+
+    def close(self) -> None:
+        self.serial.close()
+
+
+class LidarNode(Node):
+
+    def __init__(self):
+        super().__init__('lidar')
+        self.declare_parameter('device', value='/dev/ttyLIDAR')
+
+        device = self.get_parameter('device').get_parameter_value().string_value
+        self.lidar = MysteryLidar(device)
+
+        topic_name = self.get_parameter('topic').get_parameter_value().string_value
+        self.publisher = self.create_publisher(LaserScan, topic_name, 10)
+
+        self.thread = threading.Thread(target=self.node_task())
+        self.thread.start()
+
+    def node_task(self):
+        self.lidar.open()
+        while rclpy.ok():
+            frame = self.lidar.poll()
+            if frame:
+                self.publish_scan(frame)
+        self.lidar.close()
+
+    def publish_scan(self, frame: bytes):
+        msg = LaserScan()
+        # TODO decode frame into msg
+        self.publisher.publish(msg)
+
+
+def main(args=None):
+    rclpy.init(args=args)
+    lidar_node = LidarNode()
+    rclpy.spin(lidar_node)
+    lidar_node.destroy_node()
+    rclpy.shutdown()
+
+
+if __name__ == '__main__':
+    main()

ros_ws/src/lidar/package.xml

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+<?xml version="1.0"?>
+<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+  <name>lidar</name>
+  <version>0.0.0</version>
+  <description>Mystery LIDAR driver</description>
+  <maintainer email="bertrik@sikken.nl">Bertrik Sikken</maintainer>
+  <license>MIT</license>
+
+  <depend>std_msgs</depend>
+  <depend>rclcpp</depend>
+
+  <test_depend>ament_copyright</test_depend>
+  <test_depend>ament_flake8</test_depend>
+  <test_depend>ament_pep257</test_depend>
+  <test_depend>python3-pytest</test_depend>
+
+  <export>
+    <build_type>ament_python</build_type>
+  </export>
+</package>

ros_ws/src/lidar/resource/lidar

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+[develop]
+script_dir=$base/lib/lidar
+[install]
+install_scripts=$base/lib/lidar

ros_ws/src/lidar/setup.cfg

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+from setuptools import find_packages, setup
+
+package_name = 'lidar'
+
+setup(
+    name=package_name,
+    version='0.0.0',
+    packages=find_packages(exclude=['test']),
+    data_files=[
+        ('share/ament_index/resource_index/packages',
+            ['resource/' + package_name]),
+        ('share/' + package_name, ['package.xml']),
+    ],
+    install_requires=['setuptools'],
+    zip_safe=True,
+    maintainer='bertrik',
+    maintainer_email='bertrik@sikken.nl',
+    description='Mystery LIDAR driver',
+    license='MIT',
+    tests_require=['pytest'],
+    entry_points={
+        'console_scripts': [
+        ],
+    },
+)

ros_ws/src/lidar/setup.py

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+# Copyright 2015 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ament_copyright.main import main
+import pytest
+
+
+# Remove the `skip` decorator once the source file(s) have a copyright header
+@pytest.mark.skip(reason='No copyright header has been placed in the generated source file.')
+@pytest.mark.copyright
+@pytest.mark.linter
+def test_copyright():
+    rc = main(argv=['.', 'test'])
+    assert rc == 0, 'Found errors'

ros_ws/src/lidar/test/test_copyright.py

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+# Copyright 2017 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ament_flake8.main import main_with_errors
+import pytest
+
+
+@pytest.mark.flake8
+@pytest.mark.linter
+def test_flake8():
+    rc, errors = main_with_errors(argv=[])
+    assert rc == 0, \
+        'Found %d code style errors / warnings:\n' % len(errors) + \
+        '\n'.join(errors)

ros_ws/src/lidar/test/test_flake8.py

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+# Copyright 2015 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ament_pep257.main import main
+import pytest
+
+
+@pytest.mark.linter
+@pytest.mark.pep257
+def test_pep257():
+    rc = main(argv=['.', 'test'])
+    assert rc == 0, 'Found code style errors / warnings'