pyqgc 0.1.1

Quectel QGC protocol parser and generator

pyqgc

Current Status | Installation | Message Categories | Reading | Parsing | Generating | Serializing | Examples | Extensibility | Troubleshooting | Author & License

pyqgc is an original Python 3 parser for the QGC © protocol. QGC is a proprietary binary protocol implemented on Quectel ™ GNSS receiver modules. pyqgc can also parse NMEA 0183 © and RTCM3 © protocols via the underlying pynmeagps and pyrtcm packages from the same author - hence it covers all the protocols that Quectel QGC GNSS receivers are capable of outputting.

The pyqgc homepage is located at https://github.com/semuconsulting/pyqgc.

This is an independent project and we have no affiliation whatsoever with Quectel.

Current Status

The current alpha release implements 3 QGC RAW message types defined for the LG580P receiver, but is readily extensible. Refer to QGC_MSGIDS in qgctypes_core.py for the complete dictionary of messages currently supported. QGC protocol information sourced from public domain Quectel LG580P GNSS Protocol Specification © 2025, Quectel.

Sphinx API Documentation in HTML format is available at https://www.semuconsulting.com/pyqgc/.

Contributions welcome - please refer to CONTRIBUTING.MD. Feel free to discuss any proposed changes beforehand in the Discussion Channel.

Bug reports and Feature requests - please use the templates provided. For general queries and advice, post a message to one of the pyqgc Discussions channels.

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Installation

pyqgc is compatible with Python>=3.10. In the following, python3 & pip refer to the Python 3 executables. You may need to substitute python for python3, depending on your particular environment (on Windows it's generally python).

The recommended way to install the latest version of pyqgc is with pip:

python3 -m pip install --upgrade pyqgc

If required, pyqgc can also be installed into a virtual environment, e.g.:

python3 -m venv env
source env/bin/activate # (or env\Scripts\activate on Windows)
python3 -m pip install --upgrade pyqgc

For Conda users, pyqgc is also available from conda forge:

conda install -c conda-forge pyqgc

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QGC Message Categories - GET, SET, POLL

pyqgc divides QGC messages into three categories, signified by the mode or msgmode parameter.

mode	description	defined in
GET (0x00)	output from the receiver (the default)	qgctypes_get.py
SET (0x01)	command input to the receiver	qgctypes_set.py
POLL (0x02)	query input to the receiver	qgctypes_poll.py

If you're simply streaming and/or parsing the output of a QGC receiver, the mode is implicitly GET. If you want to create or parse an input (command or query) message, you must set the mode parameter to SET or POLL. If the parser mode is set to 0x03 (SETPOLL), pyqgc will automatically determine the applicable input mode (SET or POLL) based on the message payload.

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Reading (Streaming)

class pyqgc.qgcreader.QGCReader(stream, *args, **kwargs)

You can create a QGCReader object by calling the constructor with an active stream object. The stream object can be any viable data stream which supports a read(n) -> bytes method (e.g. File or Serial, with or without a buffer wrapper). pyqgc implements an internal SocketWrapper class to allow sockets to be read in the same way as other streams (see example below).

Individual QGC messages can then be read using the QGCReader.read() function, which returns both the raw binary data (as bytes) and the parsed data (as a QGCMessage object, via the parse() method). The function is thread-safe in so far as the incoming data stream object is thread-safe. QGCReader also implements an iterator.

The constructor accepts the following optional keyword arguments:

• protfilter: NMEA_PROTOCOL (1), QGC_PROTOCOL (2), RTCM3_PROTOCOL (4). Can be OR'd; default is NMEA_PROTOCOL | QGC_PROTOCOL | RTCM3_PROTOCOL (7)
• quitonerror: ERR_IGNORE (0) = ignore errors, ERR_LOG (1) = log errors and continue (default), ERR_RAISE (2) = (re)raise errors and terminate
• validate: VALCKSUM (0x01) = validate checksum (default), VALNONE (0x00) = ignore invalid checksum or length
• parsebitfield: 1 = parse bitfields ('X' type properties) as individual bit flags, where defined (default), 0 = leave bitfields as byte sequences
• msgmode: GET (0) (default), SET (1), POLL (2), SETPOLL (3) = automatically determine SET or POLL input mode

Example - Serial input. This example will output both QGC and NMEA messages but not RTCM3:

from serial import Serial
from pyqgc import QGCReader, VALCKSUM, ERR_LOG, NMEA_PROTOCOL, QGC_PROTOCOL
with Serial('/dev/ttyACM0', 115200, timeout=3) as stream:
  qgr = QGCReader(stream, protfilter=QGC_PROTOCOL | NMEA_PROTOCOL, quitonerror=ERR_LOG, validate=VALCKSUM, parsebitfield=1)
  raw_data, parsed_data = qgr.read()
  if parsed_data is not None:
    print(parsed_data)

<QGC(RAW-PPPB2B, msgver=1, reserved1=0, prn=60, pppstatus=0, msgtype=0, reserved2=0, msgdata=b'\x10\x35\xfc\x49\x04\x40\x01\x3f\x77\x04\x00\x11\x00\x04\x40\x01\x10\x00\x44\x00\x11\x00\x05\x80\x00\x5f\x6b\x84\x00\x11\x00\x07\x7d\x63\x10\x00\x78\x17\x0f\xfd\xd1\x02\x57\x10\x00\x44\x00\x11\x00\x04\x40\x01\x10\x00\x58\x7f\x00\x01\x81\x36\xb0')>

Example - File input (using iterator). This will only output QGC data:

from pyqgc import QGCReader, QGC_PROTOCOL
with open('QGCdata.bin', 'rb') as stream:
  qgr = QGCReader(stream, protfilter=QGC_PROTOCOL)
  for raw_data, parsed_data in qg:
    print(parsed_data)

<QGC(RAW-QZSSL6, msgver=1, reserved1=0, prn=195, rsstatus=1, msgtype=1, reserved2=0, msgdata=b'\x1a\xcf\xfc\x1d\xc3\xa9\x7f\x48\xab\x08\x92\x88\xc0\x3a\xa8\x40\x30\x02\x02\x93\xdf\xdf\xf5\xd5\xde\x43\x1c\x00\x00\x02\x04\x80\x04\x70\x00\x00\x00\x00\x82\x40\x7f\x49\xe8\x11\x08\x04\x7f\xed\x40\x0e\x9f\xe2\x01\x8b\x02\xb1\x02\x5c\x00\x5c\x06\x2f\xb1\x9f\xea\xbf\xea\xbf\xf6\x00\x5d\x07\x7b\xf1\x03\xe8\xa7\xf5\x10\x6e\xdf\xd2\x5a\x04\xa2\x3b\xfd\x0d\xfc\x40\x30\x0e\xfc\x5c\x02\x20\x0b\xc8\xbf\x0b\x03\x98\x0d\x60\x5f\x0a\x80\xd4\x03\x98\xbf\x68\xff\xdf\x03\x82\x87\xd5\x4f\xba\x01\x8c\xd7\xf0\x88\x4b\xfe\xd4\x31\xf4\x34\x08\xa0\x3a\x19\xfc\xe7\xf0\x10\x01\x17\x7c\x3a\xfd\xb8\x23\x04\xbf\xb5\x1f\xf2\xff\xe8\x93\xf7\x4c\x01\xc0\x04\x13\xbe\xd9\x00\x2b\xfe\xa2\x77\xde\xd0\x08\x7f\xd8\x4e\xfa\xbd\xff\x70\x03\x09\xdf\x89\xbf\xfa\x00\xca\x5f\xcd\x1f\xb5\xfd\xcd\x2f\xd1\xb0\x0d\xff\x8e\x97\xbf\x17\xf6\x80\x55\xfd\x29\xa0\x4a\x20\x01\xfe\x80\x28\x00\x05\xc0\xa7\xf3\x00\x15\x9c\xcd\xe1\x8b\xc4\xee\x2d\xe8\x5c\xd1\xf1\x28\xf9\xa2\x81\x83\xdf\xeb\x8e\x1b\x5f\xfe\x18\xf7\xd9\x21\x54\x33\x1c\x5c\x10')>
            

Example - Socket input (using iterator). This will output QGC, NMEA and RTCM3 data:

import socket
from pyqgc import QGCReader, NMEA_PROTOCOL, QGC_PROTOCOL, RTCM3_PROTOCOL
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as stream:
  stream.connect(("localhost", 50007))
  qgr = QGCReader(stream, protfilter=NMEA_PROTOCOL | QGC_PROTOCOL | RTCM3_PROTOCOL)
  for raw_data, parsed_data in qgr:
    print(parsed_data)

<QGC(RAW-HASE6, msgver=1, reserved1=0, prn=34, hasmode=1, msgtype=1, reserved2=0, page=2, reserved3=0, msgdata=b'\x38\xb2\x00\xe8\x50\xe9\xa0\x5e\x7f\xc6\x0d\x00\x31\xff\x2e\x00\x00\x5b\xfe\x50\x2c\xc0\xe1\x00\x00\x2f\x77\xe0\x0b\x20\xc6\xe5\x3f\x49\x79\xf0\x10\x50\x11\xf8\xcb\xeb\x7f\x31\x04\x67\xd0\x80\xf2\x05\xc0\x0e\x81\xb2\x00\xe8\x50\xe9\xa0\x5e\x7f\xc6\x0d\x00\x31\xff\x2e\x00\x00\x5b\xfe\x50\x2c\xc0\xe1\x00\x00\x2f\x77\xe0\x0b\x20\xc6\xe5\x3f\x49\x79\xf0\x10\x50\x11\xf8\xcb\xeb\x7f\x31\x04\x67\xd0\x80\xf2\x05\xc0\x0e\x81\xc8')>

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Parsing

You can parse individual QGC messages using the static QGCReader.parse(data) function, which takes a bytes array containing a binary QGC message and returns a QGCMessage object.

NB: Once instantiated, a QGCMessage object is immutable.

The parse() method accepts the following optional keyword arguments:

• validate: VALCKSUM (0x01) = validate checksum (default), VALNONE (0x00) = ignore invalid checksum or length
• parsebitfield: 1 = parse bitfields ('X' type properties) as individual bit flags, where defined (default), 0 = leave bitfields as byte sequences

Example - output message:

from pyqgc import QGCReader
msg = QGCReader.parse(b'QG\n\xb2U\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x105\xfcI\x04@\x01?w\x04\x00\x11\x00\x04@\x01\x10\x00D\x00\x11\x00\x05\x80\x00_k\x84\x00\x11\x00\x07}c\x10\x00x\x17\x0f\xfd\xd1\x02W\x10\x00D\x00\x11\x00\x04@\x01\x10\x00X\x7f\x00\x01\x816\xb0\xee\xb1')
print(msg)

<QGC(RAW-PPPB2B, msgver=0, reserved1=0, prn=0, pppstatus=0, msgtype=0, reserved2=0, msgdata=b'\x10\x35\xfc\x49\x04\x40\x01\x3f\x77\x04\x00\x11\x00\x04\x40\x01\x10\x00\x44\x00\x11\x00\x05\x80\x00\x5f\x6b\x84\x00\x11\x00\x07\x7d\x63\x10\x00\x78\x17\x0f\xfd\xd1\x02\x57\x10\x00\x44\x00\x11\x00\x04\x40\x01\x10\x00\x58\x7f\x00\x01\x81\x36\xb0')>

The QGCMessage object exposes different public attributes depending on its message type or 'identity', e.g. the RAW-PPPB2B message has the following attributes:

print(msg)
print(msg.identity)
print(msg.pppstatus)

<QGC(RAW-PPPB2B, msgver=1, reserved1=0, prn=60, pppstatus=0, msgtype=0, reserved2=0, msgdata=b'\x10\x35\xfc\x49\x04\x40\x01\x3f\x77\x04\x00\x11\x00\x04\x40\x01\x10\x00\x44\x00\x11\x00\x05\x80\x00\x5f\x6b\x84\x00\x11\x00\x07\x7d\x63\x10\x00\x78\x17\x0f\xfd\xd1\x02\x57\x10\x00\x44\x00\x11\x00\x04\x40\x01\x10\x00\x58\x7f\x00\x01\x81\x36\xb0')>
RAW-PPPB2B
0

The payload attribute always contains the raw payload as bytes. Attributes within repeating groups are parsed with a two-digit suffix (svid_01, svid_02, etc.).

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Generating

class pyqgc.qgcmessage.QGCMessage(msggrp, msgid, **kwargs)

You can create a QGCMessage object by calling the constructor with the following parameters:

1. message group (must be a valid group from pyqgc.QGC_MSGIDS)
2. message id (must be a valid id from pqgc.QGC_MSGIDS)
3. (optional) a series of keyword parameters representing the message payload
4. (optional) parsebitfield keyword - 1 = define bitfields as individual bits (default), 0 = define bitfields as byte sequences

The 'message group' and 'message id' parameters must be passed as bytes.

The message payload can be defined via keyword arguments in one of three ways:

1. A single keyword argument of payload containing the full payload as a sequence of bytes (any other keyword arguments will be ignored). NB the payload keyword argument must be used for message types which have a 'variable by size' repeating group.
2. One or more keyword arguments corresponding to individual message attributes. Any attributes not explicitly provided as keyword arguments will be set to a nominal value according to their type.
3. If no keyword arguments are passed, the payload is assumed to be null.

Example - to generate a RAW-PPPB2B command (msggrp 0x0a, msgid 0xb2) from individual keyword arguments:

from pyqgc import QGCMessage
msg = QGCMessage(
    b"\x0a",
    b"\xb2",
    parsebitfield=1,
    msgver=1,
    prn=60,
    pppstatus=0,
    msgtype=0,
    msgdata=b"\x10\x35\xfc\x49\x04\x40\x01\x3f\x77\x04\x00\x11\x00\x04\x40\x01\x10\x00\x44\x00\x11\x00\x05\x80\x00\x5f\x6b\x84\x00\x11\x00\x07\x7d\x63\x10\x00\x78\x17\x0f\xfd\xd1\x02\x57\x10\x00\x44\x00\x11\x00\x04\x40\x01\x10\x00\x58\x7f\x00\x01\x81\x36\xb0",
)
print(msg)

<QGC(RAW-PPPB2B, msgver=1, reserved1=0, prn=60, pppstatus=0, msgtype=0, reserved2=0, msgdata=b'\\x10\\x35\\xfc\\x49\\x04\\x40\\x01\\x3f\\x77\\x04\\x00\\x11\\x00\\x04\\x40\\x01\\x10\\x00\\x44\\x00\\x11\\x00\\x05\\x80\\x00\\x5f\\x6b\\x84\\x00\\x11\\x00\\x07\\x7d\\x63\\x10\\x00\\x78\\x17\\x0f\\xfd\\xd1\\x02\\x57\\x10\\x00\\x44\\x00\\x11\\x00\\x04\\x40\\x01\\x10\\x00\\x58\\x7f\\x00\\x01\\x81\\x36\\xb0')>
        

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Serializing

The QGCMessage class implements a serialize() method to convert a QGCMessage object to a bytes array suitable for writing to an output stream.

e.g. to create and send a RAW-PPPB2B message:

from serial import Serial
from pyqgc import QGCMessage
serialOut = Serial('COM7', 115200, timeout=5)
print(msg)
output = msg.serialize()
print(output)
serialOut.write(output)

<QGC(RAW-PPPB2B, msgver=0, reserved1=0, prn=0, pppstatus=0, msgtype=0, reserved2=0, msgdata=b'\x10\x35\xfc\x49\x04\x40\x01\x3f\x77\x04\x00\x11\x00\x04\x40\x01\x10\x00\x44\x00\x11\x00\x05\x80\x00\x5f\x6b\x84\x00\x11\x00\x07\x7d\x63\x10\x00\x78\x17\x0f\xfd\xd1\x02\x57\x10\x00\x44\x00\x11\x00\x04\x40\x01\x10\x00\x58\x7f\x00\x01\x81\x36\xb0')>
b'QG\n\xb2U\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x105\xfcI\x04@\x01?w\x04\x00\x11\x00\x04@\x01\x10\x00D\x00\x11\x00\x05\x80\x00_k\x84\x00\x11\x00\x07}c\x10\x00x\x17\x0f\xfd\xd1\x02W\x10\x00D\x00\x11\x00\x04@\x01\x10\x00X\x7f\x00\x01\x816\xb0\xee\xb1'

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Examples

The following command line examples can be found in the \examples folder:

1. qgcusage.py illustrates basic usage of the QGCMessage and QGCReader classes.

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Extensibility

The QGC protocol is principally defined in the modules QGCtypes_*.py as a series of dictionaries. Message payload definitions must conform to the following rules:

1. attribute names must be unique within each message class
2. attribute types must be one of the valid types (S1, U2, X4, etc.)
3. if the attribute is scaled, attribute type is list of [attribute type as string (S1, U2, etc.), scaling factor as float] e.g. {"lat": [I4, 1e-7]}
4. repeating or bitfield groups must be defined as a tuple ('numr', {dict}), where:
   'numr' is either:
     a. an integer representing a fixed number of repeats e.g. 32
     b. a string representing the name of a preceding attribute containing the number of repeats e.g. 'numCh'
     c. an 'X' attribute type ('X1', 'X2', 'X4', etc) representing a group of individual bit flags
     d. 'None' for a 'variable by size' repeating group. Only one such group is permitted per payload and it must be at the end.
   {dict} is the nested dictionary of repeating items or bitfield group

Repeating attribute names are parsed with a two-digit suffix (svid_01, svid_02, etc.). Nested repeating groups are supported.

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Troubleshooting

1. UnicodeDecode errors.

• If reading QGC data from a log file, check that the file.open() procedure is using the rb (read binary) setting e.g. stream = open('QGCdata.log', 'rb').

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Author & License Information

[e-mail]

pyqgc is maintained entirely by unpaid volunteers. It receives no funding from advertising or corporate sponsorship. If you find the utility useful, please consider sponsoring the project with the price of a coffee...