nmea_topic_serial_reader.py

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"""Defines the main method for the nmea_topic_serial_reader executable."""

import serial

from nmea_msgs.msg import Sentence
import rospy

from libnmea_navsat_driver.driver import RosNMEADriver


def main():
    """Create and run the nmea_topic_serial_reader ROS node.

    Opens a serial device and publishes data from the device as nmea_msgs.msg.Sentence messages.

    ROS parameters:
        ~port (str): Path of the serial device to open.
        ~baud (int): Baud rate to configure the serial device.

    ROS publishers:
        nmea_sentence (nmea_msgs.msg.Sentence): Publishes each line from the open serial device as a new
            message. The header's stamp is set to the rostime when the data is read from the serial device.
    """
    rospy.init_node('nmea_topic_serial_reader')

    nmea_pub = rospy.Publisher("nmea_sentence", Sentence)

    serial_port = rospy.get_param('~port', '/dev/ttyUSB0')
    serial_baud = rospy.get_param('~baud', 4800)

    # Get the frame_id
    frame_id = RosNMEADriver.get_frame_id()

    try:
        GPS = serial.Serial(port=serial_port, baudrate=serial_baud, timeout=2)
        while not rospy.is_shutdown():
            data = GPS.readline().strip()

            sentence = Sentence()
            sentence.header.stamp = rospy.get_rostime()
            sentence.header.frame_id = frame_id
            sentence.sentence = data

            nmea_pub.publish(sentence)

    except rospy.ROSInterruptException:
        GPS.close()  # Close GPS serial port