ATGM336H_NMEA_ROS2

ROS2 pkg for ATGM336H GPS Module

This pkg contains gps_node which publishes following NMEA protocol topics;

• /gps/gpgga: Message from GNGGA String

  data type	Data	Description
  float64	utc_seconds	UTC time status of position (hours/minutes/seconds/ decimal seconds)
  float64	lat	Latitude (DDmm.mm)
  float64	lon	Latitude direction (N = North, S = South)
  string	lat_dir	Longitude (DDDmm.mm)
  string	lon_dir	Longitude direction (E = East, W = West)
  uint32	gps_qual	refer to Table: GPS Quality Indicators
  uint32	num_sats	Number of satellites in use. May be different to the number in view
  float32	hdop	Horizontal dilution of precision
  float32	alt	Antenna altitude above/below mean sea level
  string	altitude_units	Units of antenna altitude (M = metres)
  float32	undulation	Undulation - the relationship between the geoid and the WGS84 ellipsoid
  string	undulation_units	Units of undulation (M = metres)
  uint32	diff_age	Age of correction data (in seconds) The maximum age reported here is limited to 99 seconds
  string	station_id	Differential base station ID

• /gpa/gpgsa: Message from GPGSA String

  data type	Data	Description
  string	auto_manual_mode	A = Automatic 2D/3D M = MAnual, forced to operate in 2D or 3D
  uint8	fix_mode	Mode: 1 = Fix not available 2 = 2D 3 = 3D
  uint8[]	sv_ids	PRN numbers of satellites used in solution (null for unused fields), total of 12 fields GPS = 1 to 32 SBAS = 33 to 64 (add 87 for PRN number) GLO = 65 to 96
  float32	pdop	Position dilution of precision
  float32	hdop	Horizontal dilution of precision
  float32	vdop	Vertical dilution of precision

• /gpa/gpgsv: Message from GPGSV String
  

  • Total number of satellites in view and data about satellites
  • Because the NMEA sentence is limited to 4 satellites per message, several of these messages may need to be synthesized to get data about all visible

  data type	Data	Description
  uint8	n_msgs	Total number of messages (1-9)
  uint8	msg_number	Message number (1-9)
  uint8	n_satellites	Total number of satellites in view. May be different than the number of satellites in use (see also the GPGGA log)
  GpgsvSatellite[]	satellites - prn - elev - azimuth - SNR	prn: Satellite PRN number - GPS = 1 to 32 - Galileo = 1 to 36 - BeiDou = 1 to 63 - NavIC = 1 to 14 - QZSS = 1 to 10 - SBAS = 33 to 64 (add 87 for PRN#s) - GLONASS = 65 to 96 elev: Elevation, degrees, 90 maximum azimuth: Azimuth, degrees True, 000 to 359 SNR: SNR (C/No) 00-99 dB, null when not tracking

• /gpg/gprmc: Message from GNRMC String

  data type	Data	Description
  float64	utc_seconds	UTC of position hhmmss.s
  float64	position_status	Position status (A = data valid, V = data invalid)
  float64	lat	Latitude (DDmm.mm)
  float32	lon	Longitude (DDDmm.mm)
  string	lat_dir	Latitude direction: (N = North, S = South)
  string	lon_dir	Longitude direction: (E = East, W = West)
  float32	speed	Speed over ground, knots
  float32	track	Track made good, degrees True
  string	date	Date: dd/mm/yy (xxxxxx)
  float32	mag_var	Magnetic variation, degrees Note that this field is the actual magnetic variation and will always be positive. The direction of the magnetic variation is always positive.
  string	mag_var_direction	Magnetic variation direction E/W Easterly variation (E) subtracts from True course. Westerly variation (W) adds to True course.
  string	mode_indicator	Positioning system mode indicator, see Table: NMEA Positioning System Mode Indicator

• /gpg/sentence: A message representing a single NMEA0183 sentence.

Install dependencies:

• pyserial: pip3 install pyserial
• nmea_msgs: sudo apt-get install ros-foxy-nmea-msgs

Install pkg:

sudo apt-get install ros-$ROS_DISTRO-nmea_msgs

mkdir -p ~/ros2_ws/src
cd ~/ros2_ws/src
git clone https://github.com/NDHANA94/ATGM336H_NMEA_ROS2.git
cd ~/ros2_ws
colcon build

Execute:

cd ~/ros2_ws
source install/setup.bash
ros2 run atgm336h5n3x nmea_node --dev /dev/ttyUSB0