146 lines
5.2 KiB
Python
146 lines
5.2 KiB
Python
import threading
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import time
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from platypush.backend import Backend
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from platypush.message.event.gps import GPSVersionEvent, GPSDeviceEvent, GPSUpdateEvent
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class GpsBackend(Backend):
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"""
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This backend can interact with a GPS device and listen for events.
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Once installed gpsd you need to run it and associate it to your device. Example if your GPS device communicates
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over USB and is available on /dev/ttyUSB0::
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[sudo] gpsd /dev/ttyUSB0 -F /var/run/gpsd.sock
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The best option is probably to run gpsd at startup as a systemd service.
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"""
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_fail_sleep_time = 5.0
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_lat_lng_tolerance = 1e-5
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_alt_tolerance = 0.5
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def __init__(self, gpsd_server='localhost', gpsd_port=2947, **kwargs):
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"""
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:param gpsd_server: gpsd daemon server name/address (default: localhost)
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:type gpsd_server: str
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:param gpsd_port: Port of the gpsd daemon (default: 2947)
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:type gpsd_port: int or str
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"""
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super().__init__(**kwargs)
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self.gpsd_server = gpsd_server
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self.gpsd_port = gpsd_port
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self._session = None
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self._session_lock = threading.RLock()
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self._devices = {}
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def _get_session(self):
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import gps
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with self._session_lock:
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if not self._session:
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self._session = gps.gps(
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host=self.gpsd_server, port=self.gpsd_port, reconnect=True
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)
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self._session.stream(gps.WATCH_ENABLE | gps.WATCH_NEWSTYLE)
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return self._session
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def _gps_report_to_event(self, report):
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if report.get('class').lower() == 'version':
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return GPSVersionEvent(
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release=report.get('release'),
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rev=report.get('rev'),
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proto_major=report.get('proto_major'),
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proto_minor=report.get('proto_minor'),
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)
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if report.get('class').lower() == 'devices':
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for device in report.get('devices', []):
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if device.get(
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'path'
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) not in self._devices or device != self._devices.get('path'):
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# noinspection DuplicatedCode
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self._devices[device.get('path')] = device
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return GPSDeviceEvent(
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path=device.get('path'),
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activated=device.get('activated'),
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native=device.get('native'),
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bps=device.get('bps'),
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parity=device.get('parity'),
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stopbits=device.get('stopbits'),
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cycle=device.get('cycle'),
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driver=device.get('driver'),
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)
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if report.get('class').lower() == 'device':
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# noinspection DuplicatedCode
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self._devices[report.get('path')] = report
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return GPSDeviceEvent(
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path=report.get('path'),
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activated=report.get('activated'),
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native=report.get('native'),
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bps=report.get('bps'),
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parity=report.get('parity'),
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stopbits=report.get('stopbits'),
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cycle=report.get('cycle'),
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driver=report.get('driver'),
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)
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if report.get('class').lower() == 'tpv':
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return GPSUpdateEvent(
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device=report.get('device'),
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latitude=report.get('lat'),
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longitude=report.get('lon'),
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altitude=report.get('alt'),
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mode=report.get('mode'),
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epv=report.get('epv'),
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eph=report.get('eph'),
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sep=report.get('sep'),
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)
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def run(self):
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super().run()
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self.logger.info(
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'Initialized GPS backend on {}:{}'.format(self.gpsd_server, self.gpsd_port)
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)
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last_event = None
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while not self.should_stop():
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try:
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session = self._get_session()
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report = session.next()
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event = self._gps_report_to_event(report)
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if event and (
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last_event is None
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or abs(
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(last_event.args.get('latitude') or 0)
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- (event.args.get('latitude') or 0)
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)
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>= self._lat_lng_tolerance
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or abs(
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(last_event.args.get('longitude') or 0)
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- (event.args.get('longitude') or 0)
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)
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>= self._lat_lng_tolerance
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or abs(
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(last_event.args.get('altitude') or 0)
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- (event.args.get('altitude') or 0)
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)
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>= self._alt_tolerance
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):
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self.bus.post(event)
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last_event = event
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except Exception as e:
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if isinstance(e, StopIteration):
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self.logger.warning(
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'GPS service connection lost, check that gpsd is running'
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)
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else:
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self.logger.exception(e)
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self._session = None
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time.sleep(self._fail_sleep_time)
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# vim:sw=4:ts=4:et:
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