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| # The MIT License (MIT) | ||
| # | ||
| # Copyright (c) 2017 Tony DiCola for Adafruit Industries | ||
| # | ||
| # Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| # of this software and associated documentation files (the "Software"), to deal | ||
| # in the Software without restriction, including without limitation the rights | ||
| # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| # copies of the Software, and to permit persons to whom the Software is | ||
| # furnished to do so, subject to the following conditions: | ||
| # | ||
| # The above copyright notice and this permission notice shall be included in | ||
| # all copies or substantial portions of the Software. | ||
| # | ||
| # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | ||
| # THE SOFTWARE. | ||
| """ | ||
| `adafruit_gps` | ||
| ==================================================== | ||
| GPS parsing module. Can parse simple NMEA data sentences from serial GPS | ||
| modules to read latitude, longitude, and more. | ||
| * Author(s): Tony DiCola, Alexandre Marquet. | ||
| Implementation Notes | ||
| -------------------- | ||
| **Hardware:** | ||
| * Adafruit `Ultimate GPS Breakout <https://www.adafruit.com/product/746>`_ | ||
| * Adafruit `Ultimate GPS FeatherWing <https://www.adafruit.com/product/3133>`_ | ||
| **Software and Dependencies:** | ||
| * MicroPython: | ||
| https://github.com/micropython/micropython | ||
| """ | ||
| __version__ = "0.0.0-auto.0" | ||
| __repo__ = "https://github.com/alexmrqt/Adafruit_CircuitPython_GPS.git" | ||
|
|
||
| # Internal helper parsing functions. | ||
| # These handle input that might be none or null and return none instead of | ||
| # throwing errors. | ||
| def _parse_degrees(nmea_data): | ||
| # Parse a NMEA lat/long data pair 'dddmm.mmmm' into a pure degrees value. | ||
| # Where ddd is the degrees, mm.mmmm is the minutes. | ||
| if nmea_data is None or len(nmea_data) < 3: | ||
| return None | ||
| raw = float(nmea_data.decode()) | ||
| deg = raw // 100 | ||
| minutes = raw % 100 | ||
| return deg + minutes/60 | ||
|
|
||
| def _parse_int(nmea_data): | ||
| if nmea_data is None or nmea_data == b'': | ||
| return None | ||
| return int(nmea_data) | ||
|
|
||
| def _parse_float(nmea_data): | ||
| if nmea_data is None or nmea_data == b'': | ||
| return None | ||
| return float(nmea_data.decode()) | ||
|
|
||
| # lint warning about too many attributes disabled | ||
| #pylint: disable-msg=R0902 | ||
| class GPS: | ||
| """GPS parsing module. Can parse simple NMEA data sentences from serial GPS | ||
| modules to read latitude, longitude, and more. | ||
| :param uart: The `UART` object to use. | ||
| """ | ||
| def __init__(self, uart): | ||
| self._uart = uart | ||
| # Initialize null starting values for GPS attributes. | ||
| self.timestamp_utc = None | ||
| self.latitude = None | ||
| self.longitude = None | ||
| self.fix_quality = None | ||
| self.satellites = None | ||
| self.horizontal_dilution = None | ||
| self.altitude_m = None | ||
| self.height_geoid = None | ||
| self.velocity_knots = None | ||
| self.speed_knots = None | ||
| self.track_angle_deg = None | ||
|
|
||
| def update(self): | ||
| """Check for updated data from the GPS module and process it | ||
| accordingly. Returns True if new data was processed, and False if | ||
| nothing new was received. | ||
| """ | ||
| # Grab a sentence and check its data type to call the appropriate | ||
| # parsing function. | ||
| sentence = self._parse_sentence() | ||
| if sentence is None: | ||
| return False | ||
| data_type, args = sentence | ||
| data_type = data_type.upper() | ||
| if data_type == b'GPGGA': # GGA, 3d location fix | ||
| self._parse_gpgga(args) | ||
| elif data_type == b'GPRMC': # RMC, minimum location info | ||
| self._parse_gprmc(args) | ||
| return True | ||
|
|
||
| def send_command(self, command, add_checksum=True): | ||
| """Send a command string to the GPS. If add_checksum is True (the | ||
| default) a NMEA checksum will automatically be computed and added. | ||
| Note you should NOT add the leading $ and trailing * to the command | ||
| as they will automatically be added! | ||
| """ | ||
| self._uart.write('$') | ||
| self._uart.write(command) | ||
| if add_checksum: | ||
| checksum = 0 | ||
| for char in command: | ||
| checksum ^= ord(char) | ||
| self._uart.write('*') | ||
| self._uart.write('{:02x}'.format(checksum).upper()) | ||
| self._uart.write('\r\n') | ||
|
|
||
| @property | ||
| def has_fix(self): | ||
| """True if a current fix for location information is available.""" | ||
| return self.fix_quality is not None and self.fix_quality >= 1 | ||
|
|
||
| def _parse_sentence(self): | ||
| # Parse any NMEA sentence that is available. | ||
| sentence = self._uart.readline() | ||
| if sentence is None or sentence == b'' or len(sentence) < 1: | ||
| return None | ||
| sentence = sentence.strip() | ||
| # Look for a checksum and validate it if present. | ||
| if len(sentence) > 7 and sentence[-3] == ord('*'): | ||
| # Get included checksum, then calculate it and compare. | ||
| expected = int(sentence[-2:], 16) | ||
| actual = 0 | ||
| for i in range(1, len(sentence)-3): | ||
| actual ^= sentence[i] | ||
| if actual != expected: | ||
| return None # Failed to validate checksum. | ||
| # Remove checksum once validated. | ||
| sentence = sentence[:-3] | ||
| # Parse out the type of sentence (first string after $ up to comma) | ||
| # and then grab the rest as data within the sentence. | ||
| delineator = sentence.find(b',') | ||
| if delineator == -1: | ||
| return None # Invalid sentence, no comma after data type. | ||
| data_type = sentence[1:delineator] | ||
| return (data_type, sentence[delineator+1:]) | ||
|
|
||
| def _parse_gpgga(self, args): | ||
| # Parse the arguments (everything after data type) for NMEA GPGGA | ||
| # 3D location fix sentence. | ||
| data = args.split(b',') | ||
| if data is None or len(data) != 14: | ||
| return # Unexpected number of params. | ||
| # Parse fix time. | ||
| time_utc = int(_parse_float(data[0])) | ||
| if time_utc is not None: | ||
| hours = time_utc // 10000 | ||
| mins = (time_utc // 100) % 100 | ||
| secs = time_utc % 100 | ||
| # Set or update time to a friendly python time struct. | ||
| if self.timestamp_utc is not None: | ||
| self.timestamp_utc = ( | ||
| self.timestamp_utc[0], self.timestamp_utc[1], | ||
| self.timestamp_utc[2], hours, mins, secs, 0, 0) | ||
| else: | ||
| self.timestamp_utc = (0, 0, 0, hours, mins, secs, 0, 0) | ||
| # Parse latitude and longitude. | ||
| self.latitude = _parse_degrees(data[1]) | ||
| if self.latitude is not None and \ | ||
| data[2] is not None and data[2].lower() == b's': | ||
| self.latitude *= -1.0 | ||
| self.longitude = _parse_degrees(data[3]) | ||
| if self.longitude is not None and \ | ||
| data[4] is not None and data[4].lower() == b'w': | ||
| self.longitude *= -1.0 | ||
| # Parse out fix quality and other simple numeric values. | ||
| self.fix_quality = _parse_int(data[5]) | ||
| self.satellites = _parse_int(data[6]) | ||
| self.horizontal_dilution = _parse_float(data[7]) | ||
| self.altitude_m = _parse_float(data[8]) | ||
| self.height_geoid = _parse_float(data[10]) | ||
|
|
||
| def _parse_gprmc(self, args): | ||
| # Parse the arguments (everything after data type) for NMEA GPRMC | ||
| # minimum location fix sentence. | ||
| data = args.split(b',') | ||
| if data is None or len(data) < 11 or data[0] is None: | ||
| return # Unexpected number of params. | ||
| # Parse fix time. | ||
| time_utc = int(_parse_float(data[0])) | ||
| if time_utc is not None: | ||
| hours = time_utc // 10000 | ||
| mins = (time_utc // 100) % 100 | ||
| secs = time_utc % 100 | ||
| # Set or update time to a friendly python time struct. | ||
| if self.timestamp_utc is not None: | ||
| self.timestamp_utc = ( | ||
| self.timestamp_utc[0], self.timestamp_utc[1], | ||
| self.timestamp_utc[2], hours, mins, secs, 0, 0) | ||
| else: | ||
| self.timestamp_utc = (0, 0, 0, hours, mins, secs, 0, 0) | ||
| # Parse status (active/fixed or void). | ||
| status = data[1] | ||
| self.fix_quality = 0 | ||
| if status is not None and status.lower() == b'a': | ||
| self.fix_quality = 1 | ||
| # Parse latitude and longitude. | ||
| self.latitude = _parse_degrees(data[2]) | ||
| if self.latitude is not None and \ | ||
| data[3] is not None and data[3].lower() == b's': | ||
| self.latitude *= -1.0 | ||
| self.longitude = _parse_degrees(data[4]) | ||
| if self.longitude is not None and \ | ||
| data[5] is not None and data[5].lower() == b'w': | ||
| self.longitude *= -1.0 | ||
| # Parse out speed and other simple numeric values. | ||
| self.speed_knots = _parse_float(data[6]) | ||
| self.track_angle_deg = _parse_float(data[7]) | ||
| # Parse date. | ||
| if data[8] is not None and len(data[8]) == 6: | ||
| day = int(data[8][0:2]) | ||
| month = int(data[8][2:4]) | ||
| year = 2000 + int(data[8][4:6]) # Y2k bug, 2 digit date assumption. | ||
| # This is a problem with the NMEA | ||
| # spec and not this code. | ||
| if self.timestamp_utc is not None: | ||
| # Replace the timestamp with an updated one. | ||
| self.timestamp_utc = (year, month, day, | ||
| self.timestamp_utc[3], | ||
| self.timestamp_utc[4], | ||
| self.timestamp_utc[5], | ||
| 0, | ||
| 0) | ||
| else: | ||
| # Time hasn't been set so create it. | ||
| self.timestamp_utc = (year, month, day, 0, 0, 0, 0, 0) |
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