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Adafruit Ultimate GPS Example
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adafruit_gps.py
# 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
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:**
* Adafruit CircuitPython firmware for the ESP8622 and M0-based boards:
https://github.com/adafruit/circuitpython/releases
"""
import time
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/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)
deg = raw // 100
minutes = raw % 100
return deg + minutes/60
def _parse_int(nmea_data):
if nmea_data is None or nmea_data == '':
return None
return int(nmea_data)
def _parse_float(nmea_data):
if nmea_data is None or nmea_data == '':
return None
return float(nmea_data)
def _parse_str(nmea_data):
if nmea_data is None or nmea_data == '':
return None
return str(nmea_data)
# 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.
"""
def __init__(self, uart, debug=False):
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.fix_quality_3d = None
self.satellites = None
self.satellites_prev = None
self.horizontal_dilution = None
self.altitude_m = None
self.height_geoid = None
self.speed_knots = None
self.track_angle_deg = None
self.sats = None
self.isactivedata = None
self.true_track = None
self.mag_track = None
self.sat_prns = None
self.sel_mode = None
self.pdop = None
self.hdop = None
self.vdop = None
self.total_mess_num = None
self.mess_num = None
self.debug = debug
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.
try:
sentence = self._parse_sentence()
except UnicodeError:
return None
if sentence is None:
return False
if self.debug:
print(sentence)
data_type, args = sentence
data_type = bytes(data_type.upper(), "ascii")
# return sentence
if data_type == b'GPGLL': # GLL, Geographic Position – Latitude/Longitude
self._parse_gpgll(args)
elif data_type == b'GPRMC': # RMC, minimum location info
self._parse_gprmc(args)
elif data_type == b'GPGGA': # GGA, 3d location fix
self._parse_gpgga(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(b'$')
self._uart.write(command)
if add_checksum:
checksum = 0
for char in command:
checksum ^= char
self._uart.write(b'*')
self._uart.write(bytes('{:02x}'.format(checksum).upper(), "ascii"))
self._uart.write(b'\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
@property
def has_3d_fix(self):
"""Returns true if there is a 3d fix available.
use has_fix to determine if a 2d fix is available,
passing it the same data"""
return self.fix_quality_3d is not None and self.fix_quality_3d >= 2
@property
def datetime(self):
"""Return struct_time object to feed rtc.set_time_source() function"""
return self.timestamp_utc
def _parse_sentence(self):
# Parse any NMEA sentence that is available.
# pylint: disable=len-as-condition
# This needs to be refactored when it can be tested.
# Only continue if we have at least 32 bytes in the input buffer
if self._uart.in_waiting < 32:
return None
sentence = self._uart.readline()
if sentence is None or sentence == b'' or len(sentence) < 1:
return None
try:
sentence = str(sentence, 'ascii').strip()
except UnicodeError:
return None
# Look for a checksum and validate it if present.
if len(sentence) > 7 and sentence[-3] == '*':
# Get included checksum, then calculate it and compare.
expected = int(sentence[-2:], 16)
actual = 0
for i in range(1, len(sentence)-3):
actual ^= ord(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.
delimiter = sentence.find(',')
if delimiter == -1:
return None # Invalid sentence, no comma after data type.
data_type = sentence[1:delimiter]
return (data_type, sentence[delimiter+1:])
def _parse_gpgll(self, args):
data = args.split(',')
if data is None or data[0] is None:
return # Unexpected number of params.
# Parse latitude and longitude.
self.latitude = _parse_degrees(data[0])
if self.latitude is not None and \
data[1] is not None and data[1].lower() == 's':
self.latitude *= -1.0
self.longitude = _parse_degrees(data[2])
if self.longitude is not None and \
data[3] is not None and data[3].lower() == 'w':
self.longitude *= -1.0
time_utc = int(_parse_int(float(data[4])))
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 = time.struct_time((
0, 0, 0, hours, mins, secs, 0, 0, -1))
else:
self.timestamp_utc = time.struct_time((0, 0, 0, hours, mins,
secs, 0, 0, -1))
# Parse data active or void
self.isactivedata = _parse_str(data[5])
def _parse_gprmc(self, args):
# Parse the arguments (everything after data type) for NMEA GPRMC
# minimum location fix sentence.
data = args.split(',')
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 = time.struct_time((
self.timestamp_utc.tm_year, self.timestamp_utc.tm_mon,
self.timestamp_utc.tm_mday, hours, mins, secs, 0, 0, -1))
else:
self.timestamp_utc = time.struct_time((0, 0, 0, hours, mins,
secs, 0, 0, -1))
# Parse status (active/fixed or void).
status = data[1]
self.fix_quality = 0
if status is not None and status.lower() == '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() == '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() == '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 year 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.
# (struct_time is immutable and can't be changed in place)
self.timestamp_utc = time.struct_time((year, month, day,
self.timestamp_utc.tm_hour,
self.timestamp_utc.tm_min,
self.timestamp_utc.tm_sec,
0,
0,
-1))
else:
# Time hasn't been set so create it.
self.timestamp_utc = time.struct_time((year, month, day, 0, 0,
0, 0, 0, -1))
def _parse_gpgga(self, args):
# Parse the arguments (everything after data type) for NMEA GPGGA
# 3D location fix sentence.
data = args.split(',')
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 = time.struct_time((
self.timestamp_utc.tm_year, self.timestamp_utc.tm_mon,
self.timestamp_utc.tm_mday, hours, mins, secs, 0, 0, -1))
else:
self.timestamp_utc = time.struct_time((0, 0, 0, hours, mins,
secs, 0, 0, -1))
# 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() == '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() == '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_gpgsa(self, args):
data = args.split(',')
if data is None:
return # Unexpected number of params
# Parse selection mode
self.sel_mode = _parse_str(data[0])
# Parse 3d fix
self.fix_quality_3d = _parse_int(data[1])
satlist = list(filter(None, data[2:-4]))
self.sat_prns = {}
for i, sat in enumerate(satlist, 1):
self.sat_prns["gps{}".format(i)] = _parse_int(sat)
# Parse PDOP, dilution of precision
self.pdop = _parse_float(data[-3])
# Parse HDOP, horizontal dilution of precision
self.hdop = _parse_float(data[-2])
# Parse VDOP, vertical dilution of precision
self.vdop = _parse_float(data[-1])
def _parse_gpgsv(self, args):
# Parse the arguments (everything after data type) for NMEA GPGGA
# 3D location fix sentence.
data = args.split(',')
if data is None:
return # Unexpected number of params.
# Parse number of messages
self.total_mess_num = _parse_int(data[0]) # Total number of messages
# Parse message number
self.mess_num = _parse_int(data[1]) # Message number
# Parse number of satellites in view
self.satellites = _parse_int(data[2]) # Number of satellites
if len(data) < 3:
return
sat_tup = data[3:]
satdict = {}
for i in range(len(sat_tup)/4):
j = i*4
key = "gps{}".format(i+(4*(self.mess_num-1)))
satnum = _parse_int(sat_tup[0+j]) # Satellite number
satdeg = _parse_int(sat_tup[1+j]) # Elevation in degrees
satazim = _parse_int(sat_tup[2+j]) # Azimuth in degrees
satsnr = _parse_int(sat_tup[3+j]) # signal-to-noise ratio in dB
value = (satnum, satdeg, satazim, satsnr)
satdict[key] = value
if self.sats is None:
self.sats = {}
for satnum in satdict:
self.sats[satnum] = satdict[satnum]
try:
if self.satellites < self.satellites_prev:
for i in self.sats:
try:
if int(i[-2]) >= self.satellites:
del self.sats[i]
except ValueError:
if int(i[-1]) >= self.satellites:
del self.sats[i]
except TypeError:
pass
self.satellites_prev = self.satellites
Raw
gps.py
#!/usr/bin/env python
import serial
import time
from adafruit_gps import GPS
port = "/dev/serial/by-id/usb-FTDI_FT232R_USB_UART_A506BOT5-if00-port0"
ser = serial.Serial(port, baudrate=9600, timeout=3000)
gps = GPS(ser)
"""
PMTK_A11.pdf pg 12
Data Field：
There are totally 19 data fields that present output frequencies for the 19 supported
NMEA sentences individually.
Supported NMEA Sentences
0 NMEA_SEN_GLL, // GPGLL interval - Geographic Position - Latitude longitude
1 NMEA_SEN_RMC, // GPRMC interval - Recommended Minimum Specific GNSS Sentence
2 NMEA_SEN_VTG, // GPVTG interval - Course over Ground and Ground Speed
3 NMEA_SEN_GGA, // GPGGA interval - GPS Fix Data
4 NMEA_SEN_GSA, // GPGSA interval - GNSS DOPS and Active Satellites
5 NMEA_SEN_GSV, // GPGSV interval - GNSS Satellites in View
6 //Reserved
7 //Reserved
13 //Reserved
14 //Reserved
15 //Reserved
16 //Reserved
17 //Reserved
18 NMEA_SEN_MCHN, // PMTKCHN interval – GPS channel status
Supported Frequency Setting
0 - Disabled or not supported sentence
1 - Output once every one position fix
2 - Output once every two position fixes
3 - Output once every three position fixes
4 - Output once every four position fixes
5 - Output once every five position fixes
Example:
$PMTK314,1,1,1,1,1,5,0,0,0,0,0,0,0,0,0,0,0,0,0*2C<CR><LF>
"""
# gps.send_command(b'PMTK314,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0') # minimum
gps.send_command(b'PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0') # setup typical
# gps.send_command(b'PMTK314,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0') # everything
gps.send_command(b'PMTK220,1000') # 1 Hz
# gps.send_command(b'PMTK220,500') # 2 Hz, 500 msec
for i in range(10):
# data = ser.read(1024)
# print(data, flush=True)
time.sleep(0.5)
ok = gps.update()
if not ok or gps.has_fix is False:
print("no data")
else:
print('=' * 40) # Print a separator line.
print("Fix:", gps.has_fix)
print("Satellites:", gps.satellites)
print("Sats:", gps.sats)
print('Latitude: {0:.6f} degrees'.format(gps.latitude))
print('Longitude: {0:.6f} degrees'.format(gps.longitude))
print("Alititude [m]:", gps.altitude_m)
print("Altitude Geod [m]", gps.height_geoid)
print("Speed [knots]:", gps.speed_knots)
print("Dop: {} {} {}".format(gps.pdop, gps.hdop, gps.vdop))
print("Fix: {} {}".format(gps.fix_quality, gps.fix_quality_3d))
print("PRNs:", gps.sat_prns)
# print("Fix Raw timestamp:", gps.timestamp_utc)
print('Fix timestamp: {:02}/{:02}/{} {:02}:{:02}:{:02}'.format(
gps.timestamp_utc.tm_mon, # Grab parts of the time from the
gps.timestamp_utc.tm_mday, # struct_time object that holds
gps.timestamp_utc.tm_year, # the fix time. Note you might
gps.timestamp_utc.tm_hour, # not get all data like year, day,
gps.timestamp_utc.tm_min, # month!
gps.timestamp_utc.tm_sec))
Raw
output.txt
...========================================
Fix: True
Satellites: 8
Sats: None
Latitude: 38.750747 degrees
Longitude: -77.247683 degrees
Alititude [m]: 80.4
Altitude Geod [m] -33.5
Speed [knots]: 0.05
Dop: None None None
Fix: 1 None
PRNs: None
Fix timestamp: 07/07/2019 16:58:28
========================================
Fix: True
Satellites: 8
Sats: None
Latitude: 38.750742 degrees
Longitude: -77.247682 degrees
Alititude [m]: 80.5
Altitude Geod [m] -33.5
Speed [knots]: 0.05
Dop: None None None
Fix: 1 None
PRNs: None
Fix timestamp: 07/07/2019 16:58:29
========================================
Fix: True
Satellites: 8
Sats: None
Latitude: 38.750742 degrees
Longitude: -77.247682 degrees
Alititude [m]: 80.5
Altitude Geod [m] -33.5
Speed [knots]: 0.14
Dop: None None None
Fix: 1 None
PRNs: None
Fix timestamp: 07/07/2019 16:58:29
...
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