NMEА0183 sentence parser

nmea0183.py

import re
from functools import reduce


def nmea0183_create(arguments, proprietary='P', manufacturer_identifier='UWV'):
    """
    Create NMEА0183 sentence

    Parameters
    ----------
    arguments: array
        List of arguments where the first element is sentence identifier

    Returns
    -------
    sentence: bytearray
        Sentence ready to be transmitted through e.g. serial port
    """
    arguments = [ str(x) for x in arguments ]
    pmi = '{}{}'.format(proprietary, manufacturer_identifier)

    data = '{}{}'.format(pmi, ','.join(arguments))

    # Generate checksum
    checksum = reduce(lambda acc, byte: ord(byte) ^ acc, data, 0)
    checksum_hex = hex(checksum).lstrip('0x').upper()

    # Generate sentence
    sentence = '${}*{}\r\n'.format(data, checksum_hex)
    return sentence.encode()


def nmea0183_parse(sentence, proprietary='P', manufacturer_identifier='UWV', ignore_checksum=False):
    """
    Parse NMEА0183 sentence

    Parameters
    ----------
    sentence: bytearray
        Sentence received from e.g. serial port

    Returns
    -------
    arguments: array
        List of arguments where the first element is sentence identifier
    """
    sentence = sentence.decode()
    pmi = '{}{}'.format(proprietary, manufacturer_identifier)

    rexp = re.compile(r'\$(' + pmi + r'.*)\*([0-9A-F]{2})')
    data, checksum = re.findall(rexp, sentence).pop()

    # Verify checksum
    checksum_ref = reduce(lambda acc, byte: ord(byte) ^ acc, data, 0)
    checksum_ref_hex = hex(checksum_ref).lstrip('0x')
    assert(ignore_checksum or checksum == checksum_ref_hex)

    # Export arguments
    arguments = data.replace(pmi, '').split(',')
    return arguments