pyubx2

Current Status | Installation | Message Categories | Reading | Parsing | Generating | Serializing | Configuration Interface | Examples | Extensibility | Command Line Utility | Graphical Client | Author & License

pyubx2 is an original Python 3 library for the UBX © protocol. UBX is a proprietary binary protocol implemented on u-blox ™ GNSS/GPS receiver modules.

The pyubx2 homepage is located at https://github.com/semuconsulting/pyubx2.

This is an independent project and we have no affiliation whatsoever with u-blox.

FYI There is a companion library pynmeagps, which handles standard NMEA 0183 © GNSS/GPS messages.

Current Status

At time of writing the library implements a comprehensive set of inbound (SET/POLL) and outbound (GET) messages for u-blox GPS/GNSS devices from generation 6 through generation 10 (NEO-M6*, NEO-M7*, NEO-M8*, NEO-M9*, NEO-D9*, RCB-F9*, ZED-F9*, MAX-M10S, etc.), but is readily extensible. Refer to UBX_MSGIDS in ubxtypes_core.py for the complete dictionary of messages currently supported. UBX protocol information sourced from u-blox Interface Specifications © 2013-2021, u-blox AG.

Sphinx API Documentation in HTML format is available at https://www.semuconsulting.com/pyubx2.

Contributions welcome - please refer to CONTRIBUTING.MD.

Bug reports and Feature requests - please use the templates provided.

New in v1.2.5

1. pyubx2.UBXReader can now accommodate any RTCM3 data in the input stream, alongside UBX and/or NMEA data. See release notes for details.

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Installation

pyubx2 is compatible with Python 3.6+ and has no third-party library dependencies.

In the following, python & pip refer to the Python 3 executables. You may need to type python3 or pip3, depending on your particular environment.

The recommended way to install the latest version of pyubx2 is with pip:

python -m pip install --upgrade pyubx2

If required, pyubx2 can also be installed into a virtual environment, e.g.:

python -m pip install --user --upgrade virtualenv
python -m virtualenv env
source env/bin/activate (or env\Scripts\activate on Windows)
(env) python -m pip install --upgrade pyubx2
...
deactivate

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UBX Message Categories - GET, SET, POLL

pyubx2 divides UBX messages into three categories, signified by the mode or msgmode parameter.

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

If you're simply streaming and/or parsing the output of a UBX 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.

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Reading (Streaming)

class pyubx2.ubxreader.UBXReader(stream, *args, **kwargs)

You can create a UBXReader object by calling the constructor with an active stream object. The stream object can be any data stream which supports a read(n) -> bytes method (e.g. File or Serial, with or without a buffer wrapper).

Individual input UBX and/or NMEA messages can then be read using the UBXReader.read() function, which returns both the raw binary data (as bytes) and the parsed data (as a UBXMessage or NMEAMessage object, via the parse() method). UBXReader.read() can also return (but not decode) any RTCM3 data in the stream as a RTCMMessage object. The function is thread-safe in so far as the incoming data stream object is thread-safe. UBXReader also implements an iterator.

The constructor accepts the following optional keyword arguments:

• protfilter: 1 = NMEA, 2 = UBX, 4 = RTCM3 (can be OR'd. default is 3 - NMEA & UBX)
• quitonerror: 0 = ignore errors, 1 = log errors and continue (default), 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: 0 = GET (default), 1 = SET, 2 = POLL

Example - Serial input. This example will output both UBX and NMEA messages:

>>> from serial import Serial
>>> from pyubx2 import UBXReader
>>> stream = Serial('/dev/tty.usbmodem14101', 9600, timeout=3)
>>> ubr = UBXReader(stream)
>>> (raw_data, parsed_data) = ubr.read()
>>> print(parsed_data)

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

>>> from pyubx2 import UBXReader
>>> stream = open('ubxdata.bin', 'rb')
>>> ubr = UBXReader(stream, protfilter=2)
>>> for (raw_data, parsed_data) in ubr: print(parsed_data)
...

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Parsing

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

NB: Once instantiated, a UBXMessage 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 as individual bit flags, where defined (default), 0 = leave bitfields as byte sequences
• msgmode: 0 = GET (default), 1 = SET, 2 = POLL

Example - output (GET) message:

>>> from pyubx2 import UBXReader
>>> msg = UBXReader.parse(b'\xb5b\x05\x01\x02\x00\x06\x01\x0f\x38')
>>> print(msg)
<UBX(ACK-ACK, clsID=CFG, msgID=CFG-MSG)>
>>> msg = UBXReader.parse(b'\xb5b\x01\x12$\x000D\n\x18\xfd\xff\xff\xff\xf1\xff\xff\xff\xfc\xff\xff\xff\x10\x00\x00\x00\x0f\x00\x00\x00\x83\xf5\x01\x00A\x00\x00\x00\xf0\xdfz\x00\xd0\xa6')
>>> print(msg)
<UBX(NAV-VELNED, iTOW=16:01:48, velN=-3, velE=-15, velD=-4, speed=16, gSpeed=15, heading=1.28387, sAcc=65, cAcc=80.5272)>

Example - input (SET) message:

>>> from pyubx2 import UBXReader, SET
>>> msg = UBXReader.parse(b"\xb5b\x13\x40\x14\x00\x01\x00\x01\x02\x01\x02\x03\x04\x01\x02\x03\x04\x01\x02\x03\x04\x01\x02\x03\x04\x93\xc8", msgmode=SET)
>>> print(msg)
<UBX(MGA-INI-POS-LLH, type=1, version=0, reserved0=513, lat=6.7305985, lon=6.7305985, alt=67305985, posAcc=67305985)>

The UBXMessage object exposes different public attributes depending on its message type or 'identity', e.g. the NAV-POSLLH message has the following attributes:

>>> print(msg)
<UBX(NAV-POSLLH, iTOW=16:01:54, lon=-2.1601284, lat=52.6206345, height=86327, hMSL=37844, hAcc=38885, vAcc=16557)>
>>> msg.identity
'NAV-POSLLH'
>>> msg.lat, msg.lon
(52.6206345, -2.1601284)
>>> msg.hMSL/10**3
37.844

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

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Generating

(see below for special methods relating to the UBX configuration interface)

class pyubx2.ubxmessage.UBXMessage(ubxClass, ubxID, mode: int, **kwargs)

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

1. message class (must be a valid class from pyubx2.UBX_CLASSES)
2. message id (must be a valid id from pyubx2.UBX_MSGIDS)
3. mode (0=GET, 1=SET, 2=POLL)
4. (optional) a series of keyword parameters representing the message payload
5. (optional) parsebitfield keyword - 1 = define bitfields as individual bits (default), 0 = define bitfields as byte sequences

The 'message class' and 'message id' parameters may be passed as lookup strings, integers or 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 CFG-MSG command (msgClass 0x06, msgID 0x01) which sets the NAV-STATUS (msgClass 0x01, msgID 0x03) outbound message rate to 1 on the UART1 port, any of the following constructor formats will work:

A. Pass entire payload as bytes:

>>> from pyubx2 import UBXMessage, SET
>>> msg1 = UBXMessage(b'\x06', b'\x01', SET, payload=b'\x01\x03\x00\x01\x00\x00\x00\x00')
>>> print(msg1)
<UBX(CFG-MSG, msgClass=NAV, msgID=NAV-STATUS, rateDDC=0, rateUART1=1, rateUART2=0, rateUSB=0, rateSPI=0, reserved=0)>

B. Pass individual attributes as keyword arguments:

>>> from pyubx2 import UBXMessage, SET
>>> msg2 = UBXMessage(0x06, 0x01, SET, msgClass=0x01, msgID=0x03, rateDDC=0, rateUART1=1, rateUART2=0, rateUSB=0, rateSPI=0)
>>> print(msg2)
<UBX(CFG-MSG, msgClass=NAV, msgID=NAV-STATUS, rateDDC=0, rateUART1=1, rateUART2=0, rateUSB=0, rateSPI=0, reserved=0)>

C. Pass selected attribute as keyword argument; the rest will be set to nominal values (in this case 0):

>>> from pyubx2 import UBXMessage, SET
>>> msg3 = UBXMessage('CFG','CFG-MSG', SET, msgClass=0x01, msgID=0x03, rateUART1=1)
>>> print(msg3)
<UBX(CFG-MSG, msgClass=NAV, msgID=NAV-STATUS, rateDDC=0, rateUART1=1, rateUART2=0, rateUSB=0, rateSPI=0, reserved=0)>

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Serializing

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

e.g. to create and send a CFG-MSG command which sets the NMEA GLL (msgClass 0xf0, msgID 0x01) message rate to 1 on the receiver's UART1 and USB ports:

>>> from serial import Serial
>>> serialOut = Serial('COM7', 38400, timeout=5)
>>> from pyubx2 import UBXMessage, SET
>>> msg = UBXMessage('CFG','CFG-MSG', SET, msgClass=0xf0, msgID=0x01, rateUART1=1, rateUSB=1)
>>> print(msg)
<UBX(CFG-MSG, msgClass=NMEA-Standard, msgID=GLL, rateDDC=0, rateUART1=1, rateUART2=0, rateUSB=1, rateSPI=0, reserved=0)>
>>> output = msg.serialize()
>>> output
b'\xb5b\x06\x01\x08\x00\xf0\x01\x00\x01\x00\x01\x00\x00\x022'
>>> serialOut.write(output)

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Configuration Interface

CFG-VALSET, CFG-VALDEL and CFG-VALGET message types

Generation 9 of the UBX protocol (23.01 or greater, e.g. NEO-M9N, ZED-F9P) introduced the concept of a device configuration interface with configurable parameters being set or unset (del) in the designated memory layer(s) via the CFG-VALSET and CFG-VALDEL message types, or queried via the CFG-VALGET message type. Legacy CFG configuration message types continue to be supported but are now deprecated on Generation 9+ devices.

Optionally, batches of CFG-VALSET and CFG-VALDEL messages can be applied transactionally, with the combined configuration only being committed at the end of the transaction.

Individual configuration parameters are designated by keys, which may be in string (keyname) or hexadecimal integer (keyID) format. Keynames and their corresponding hexadecimal keyIDs and data types are defined in ubxtypes_configdb.py as UBX_CONFIG_DATABASE. Two helper methods are available to convert keyname to keyID and vice versa - cfgname2key() and cfgkey2name().

Dedicated static methods are provided to create these message types - UBXMessage.config_set(), UBXMessage.config_del() and UBXMessage.config_poll(). The following examples assume an output serial stream has been created as serialOut.

UBXMessage.config_set() (CFG-VALSET)

Sets up to 64 parameters in the designated memory layer(s).

Parameters:

1. layers - 1 = Volatile RAM, 2 = Battery-Backed RAM (BBR), 4 = External Flash (may be OR'd)
2. transaction - 0 = None, 1 = Start, 2 = Ongoing, 3 = Commit
3. cfgData - an array of up to 64 (key, value) tuples. Keys can be in either keyID (int) or keyname (str) format

>>> from pyubx2 import UBXMessage
>>> layers = 1
>>> transaction = 0
>>> cfgData = [("CFG_UART1_BAUDRATE", 9600), (0x40530001, 115200)]
>>> msg = UBXMessage.config_set(layers, transaction, cfgData)
>>> print(msg)
<UBX(CFG-VALSET, version=0, ram=1, bbr=0, flash=0, action=0, reserved0=0, cfgData_01=1, cfgData_02=0 ...)>
>>> serialOut.write(msg.serialize())

UBXMessage.config_del() (CFG-VALDEL)

Unsets (deletes) up to 64 parameter settings in the designated non-volatile memory layer(s).

Parameters:

1. layers - 2 = Battery-Backed RAM (BBR), 4 = External Flash
2. transaction - 0 = None, 1 = Start, 2 = Ongoing, 3 = Commit
3. keys - an array of up to 64 keys in either keyID (int) or keyname (str) format

>>> from pyubx2 import UBXMessage
>>> layers = 4
>>> transaction = 0
>>> keys = ["CFG_UART1_BAUDRATE", 0x40530001]
>>> msg = UBXMessage.config_del(layers, transaction, keys)
>>> print(msg)
<UBX(CFG-VALDEL, version=0, bbr=0, flash=1, action=0, reserved0=0, keys_01=1079115777, keys_02=1079181313)>
>>> serialOut.write(msg.serialize())

UBXMessage.config_poll() (CFG-VALGET)

Polls up to 64 parameters from the designated memory layer.

Parameters:

1. layer - 0 = Volatile RAM, 1 = Battery-Backed RAM (BBR), 2 = External Flash, 7 = Default (readonly)
2. position - unsigned integer representing number of items to be skipped before returning result (used when number of matches for an individual query exceeds 64)
3. keys - an array of up to 64 keys in either keyID (int) or keyname (str) format. keyIDs can use wildcards - see example below and UBX device interface specification for details.

>>> from pyubx2 import UBXMessage
>>> layer = 1
>>> position = 0
>>> keys = ["CFG_UART1_BAUDRATE", 0x40530001]
>>> msg = UBXMessage.config_poll(layer, position, keys)
>>> print(msg)
<UBX(CFG-VALGET, version=0, layer=1, position=0, keys_01=1079115777, keys_02=1079181313)>
>>> serialOut.write(msg.serialize())

Wild card queries can be performed by setting bits 0..15 of the keyID to 0xffff e.g. to retrieve all CFG_MSGOUT parameters (keyID 0x2091*) :

>>> from pyubx2 import UBXMessage
>>> layer = 1
>>> position = 0 # retrieve first 64 results
>>> keys = [0x2091ffff]
>>> msg1of3 = UBXMessage.config_poll(layer, position, keys)
>>> print(msg1of3)
<UBX(CFG-VALGET, version=0, layer=1, position=0, keys_01=546439167)>
>>> serialOut.write(msg1of3.serialize())
>>> position = 64 # retrieve next 64 results
>>> msg2of3 = UBXMessage.config_poll(layer, position, keys)
>>> print(msg2of3)
<UBX(CFG-VALGET, version=0, layer=1, position=64, keys_01=546439167)>
>>> serialOut.write(msg2of3.serialize())
>>> position = 128 # retrieve next 64 results
>>> msg3of3 = UBXMessage.config_poll(layer, position, keys)
>>> print(msg3of3)
<UBX(CFG-VALGET, version=0, layer=1, position=128, keys_01=546439167)>
>>> serialOut.write(msg3of3.serialize())

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Examples

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

1. ubxoptions.py illustrates the various options available for parsing and constructing UBX messages.
2. ubxpoller.py illustrates how to implement a simple threaded configuration polling utility for UBX messages.
3. ubxsetrates.py illustrates how to use legacy configuration messages (CFG-MSG) to set navigation message rates.
4. ubxconfigdb.py illustrates how to invoke the Generation 9 configuration database interface via CFG-VALSET, CF-VALDEL and CFG-VALGET messages.
5. ubxfactoryreset.py illustrates how to send a factory reset (CFG-CFG) command.
6. ubxfile.py illustrates how to implement a binary file reader for UBX messages using UBXReader iterator functionality.
7. gpxtracker.py illustrates a simple tool to convert a binary UBX data dump to a *.gpx track file.
8. ubxserver.py in the \examples\webserver folder illustrates a simple HTTP web server wrapper around pyubx2.UBXreader; it presents data from selected UBX messages as a web page http://localhost:8080 or a RESTful API http://localhost:8080/gps.
9. benchmark.py provides a simple performance benchmarking tool for the pyubx2 parser.

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Extensibility

The UBX protocol is principally defined in the modules ubxtypes_*.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 (I1, U2, X4, etc.)
3. if the attribute is scaled, attribute type is list of [attribute type as string (I1, 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. See CFG-VALGET, MON-SPAN, NAV-PVT, NAV-SAT and RXM-RLM by way of examples.

In most cases, a UBX message's content (payload) is uniquely defined by its class, id and mode; accommodating the message simply requires the addition of an appropriate dictionary entry to the relevant ubxtypes_*.py module(s).

However, there are a handful of message types which have multiple possible payload definitions for the same class, id and mode. These exceptional message types require dedicated routines in ubxmessage.py which examine elements of the payload itself in order to determine the appropriate dictionary definition. This currently applies to the following message types: CFG-NMEA, NAV-RELPOSNED, RXM-PMP, RXM-PMREQ, RXM-RLM, TIM-VCOCAL.

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Command Line Utility

If pyubx2 is installed using pip, a command line utility gnssdump is automatically installed into the Python 3 scripts (bin) directory. This utility is capable of streaming and parsing both NMEA and UBX data from any data stream (including Serial and File) to the terminal or to designed NMEA and/or UBX protocol handlers. It utilises the pynmeapgs library for NMEA data and pyubx2 for UBX data. gnssdump can also return (but not decode) any RTCM3 data in the stream.

The utility can output data in a variety of formats; parsed (1), raw binary (2), hexadecimal string (4), tabulated hexadecimal (8) or any combination thereof.

Any one of the following data stream specifiers must be provided:

• stream: any instance of a stream class which implements a read(n) -> bytes method
• filename: name of binary input file e.g. logfile.bin
• port: serial port e.g. COM3 or /dev/ttyACM1

For help and full list of optional arguments, type:

> gnssdump -h

Assuming the Python 3 scripts (bin) directory is in your PATH, the CLI utility may be invoked from the shell thus:

Serial input example (with simple external UBX protocol handler):

> gnssdump port=/dev/ttyACM1 baud=9600 timeout=5 quitonerror=1 protfilter=2 msgfilter=NAV-PVT ubxhandler="lambda msg: print(f'lat: {msg.lat}, lon: {msg.lon}')"

Parsing GNSS data stream from serial: Serial<id=0x10fe8f100, open=True>(port='/dev/ttyACM1', baudrate=9600, bytesize=8, parity='N', stopbits=1, timeout=5, xonxoff=False, rtscts=False, dsrdtr=False)...

lat: 51.352179, lon: -2.130762
lat: 51.352155, lon: -2.130751

File input example (in tabulated hexadecimal format):

> gnssdump filename=pygpsdata.log quitonerror=2 format=8 protfilter=1 msgfilter=GPGGA,GPGSA

Parsing GNSS data stream from file: <_io.BufferedReader name='pygpsdata.log'>...

000: 2447 5047 4741 2c30 3830 3234 372e 3030  | b'$GPGGA,080247.00' |
016: 2c35 3332 372e 3034 3330 302c 4e2c 3030  | b',5327.04300,N,00' |
032: 3231 342e 3431 3338 352c 572c 312c 3037  | b'214.41385,W,1,07' |
048: 2c31 2e36 332c 3336 2e37 2c4d 2c34 382e  | b',1.63,36.7,M,48.' |
064: 352c 4d2c 2c2a 3737 0d0a                 | b'5,M,,*77\r\n' |

000: 2447 5047 5341 2c41 2c33 2c30 322c 3133  | b'$GPGSA,A,3,02,13' |
016: 2c32 302c 3037 2c30 352c 3330 2c30 392c  | b',20,07,05,30,09,' |
032: 2c2c 2c2c 2c32 2e34 342c 312e 3633 2c31  | b',,,,,2.44,1.63,1' |
048: 2e38 322a 3035 0d0a                      | b'.82*05\r\n' |

The gnssdump utility implements a new GNSSStreamer class which may be used directly within Python application code via:

>>> from pyubx2cli import GNSSStreamer

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Graphical Client

A python/tkinter graphical GPS client which supports both NMEA and UBX protocols (via pynmeagps and pyubx2 respectively) is available at:

https://github.com/semuconsulting/PyGPSClient

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Author & License Information

semuadmin@semuconsulting.com

pyubx2 is maintained entirely by volunteers. If you find it useful, a small donation would be greatly appreciated!