Initial version.

bin/user/aprs.py

@@ -0,0 +1,123 @@
+from datetime import datetime
+import os
+
+import weeutil.weeutil
+import weewx.engine
+import weewx.units
+
+
+class APRS(weewx.engine.StdService):
+    def __init__(self, engine, config_dict):
+        super(APRS, self).__init__(engine, config_dict)
+        conf = config_dict['APRS']
+        self._output_filename = conf['output_filename']
+        self._output_filename_tmp = self._output_filename + '.tmp'
+        self._include_position = int(conf.get('include_position', 0))
+        self._symbol_table = conf.get('symbol_table', '/')
+        self._symbol_code = conf.get('symbol_code', '_')
+        self._comment = conf.get('comment', '')
+
+        self._message_type = '_'  # Weather report (no position)
+        self._time_format = '%m%d%H%M'
+        self._latitude = None
+        self._longitude = None
+        self._wind_direction_marker = 'c'
+        self._wind_speed_marker = 's'
+        if self._include_position:
+            # Position with timestamp (no APRS messaging)
+            self._message_type = '/'
+            self._time_format = '%d%H%Mz'
+            self._latitude = ''.join(weeutil.weeutil.latlon_string(
+                self.engine.stn_info.latitude_f,
+                ('N', 'S'), 'lat'))
+            self._longitude = ''.join(weeutil.weeutil.latlon_string(
+                self.engine.stn_info.longitude_f,
+                ('E', 'W'), 'lon'))
+            self._wind_direction_marker = ''
+            self._wind_speed_marker = '/'
+
+        self.bind(weewx.NEW_ARCHIVE_RECORD, self._handle_new_archive_record)
+
+    def _handle_new_archive_record(self, event):
+        """Generate a positionless APRS weather report and write it to a file"""
+        record = event.record
+        data = [
+            self._message_type,
+            datetime.strftime(
+                datetime.utcfromtimestamp(record['dateTime']),
+                self._time_format),
+        ]
+        if self._include_position:
+            data.append(self._latitude)
+            data.append(self._symbol_table)
+            data.append(self._longitude)
+            data.append(self._symbol_code)
+
+        if record.get('windDir') is not None:
+            # Wind direction (in degrees)
+            # Wind from North needs to be reported as 360.
+            # Wind from 0 means N/A in the APRS standard.
+            # We need to make sure it does not get to 0, so do not rely on
+            # the format string rouding, but round to no decimals before
+            # comparing with 0
+            wind_dir = int(round(record['windDir'], 0))
+            if wind_dir <= 0:
+                wind_dir = 360
+            data.append('%s%03u' % (self._wind_direction_marker,
+                                    wind_dir))
+        else:
+            data.append('%s...' % self._wind_direction_marker)
+
+        if record.get('wind_average') is not None:
+            # Sustained one-minute wind speed (in mph)
+            data.append('%s%03.f' % (self._wind_speed_marker,
+                                     record['wind_average']))
+        else:
+            data.append('%s...' % self._wind_speed_marker)
+
+        if record.get('windGust') is not None:
+            # Gust (peak wind speed in mph in the last 5 minutes)
+            data.append('g%03.f' % record['wind_average'])
+        else:
+            data.append('g...')
+
+        if record.get('outTemp') is not None:
+            # Temperature (in degrees Fahrenheit)
+            data.append('t%03.f' % record['outTemp'])
+        else:
+            data.append('t...')
+
+        if record.get('rainRate') is not None:
+            # Rainfall (in hundredths of an inch) in the last hour
+            data.append('r%03.f' % (record['rainRate'] * 100))
+
+        if record.get('daily_rain') is not None:
+            # Rainfall (in hundredths of an inch) since midnight
+            data.append('P%03.f' % (record['daily_rain'] * 100))
+
+        if record.get('outHumidity') is not None:
+            # Humidity (in %. 00 = 100%)
+            # We need to make sure it does not get over 99, so do not rely on
+            # the format string rouding, but round to no decimals before
+            # comparing with 100
+            humidity = int(round(record['outHumidity'], 0))
+            if humidity >= 100:
+                humidity = 0
+            data.append('h%02u' % humidity)
+
+        if record.get('barometer') is not None:
+            # Barometric pressure (in tenths of millibars/tenths of hPascal)
+            barometer = weewx.units.convert(
+                (record['barometer'], 'inHg', 'group_pressure'),
+                'mbar')[0] * 10
+            data.append('b%05.f' % barometer)
+
+        if self._comment:
+            data.append(self._comment)
+
+        wxdata = ''.join(data)
+
+        # Atomic update of self._output_filename.
+        with open(self._output_filename_tmp, 'w') as f:
+            f.write(wxdata)
+        os.rename(self._output_filename_tmp, self._output_filename)

install.py

@@ -0,0 +1,27 @@
+from setup import ExtensionInstaller
+
+
+def loader():
+    return APRSInstaller()
+
+
+class APRSInstaller(ExtensionInstaller):
+    def __init__(self):
+        super(APRSInstaller, self).__init__(
+            version='0.1',
+            name='aprs',
+            description='Write archive data in APRS positionless format.',
+            author='Ludovico Cavedon (K6LUD)',
+            author_email='[email protected]',
+            process_services='user.aprs.APRS',
+            config={
+                'APRS': {
+                    'output_filename': '/dev/shm/aprs.pkt',
+                    'include_position': 0,
+                    'symbol_table': '/',
+                    'symbol_code': '_',
+                    'comment': '',
+                },
+            },
+            files=[('bin/user', ['bin/user/aprs.py'])]
+        )

license.txt

@@ -0,0 +1,19 @@
+Copyright (c) 2016 Ludovico Cavedon (K6LUD) <[email protected]>
+
+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.

readme.txt

@@ -0,0 +1,43 @@
+aprs - weewx extension for generating APRS-compliant packets
+
+This weewx[1] extension allows the generation of APRS-compliant packets
+containing weather information collected by weewx.
+This extension was written for the purpose of easy integration with aprx[2].
+When this extension is enabled, weewx will generate a new APRS packet every
+StdArchive.archive_interval seconds.
+
+Installation:
+    wee_extension --install aprs.tar.gz
+
+Configuration:
+    [APRS]
+        # The APRS weather packet payload will be written in output_filename
+        output_filename = /dev/shm/aprs.pkt
+        # include_position:
+        # 0: a positionless weather report will be generated (default)
+        # 1: a weather report with position will be generated
+        include_position = 1
+        # In case of a position packet, symbol_table and symbol_code will
+        # determine what symbol will be used to display the station (e.g. on
+        # aprs.fi). "/_" is the default and will generate a blue WX icon.
+        # A positionless packet does not include a symbol specification and
+        # these two settings will be ignored
+        symbol_table = /
+        symbol_code = _
+        # The string in comment will be appended to the end of the packet.
+        comment = SBARC U2k WX station
+
+Example of integration in the aprx configuration:
+    <beacon>
+    beaconmode both  # Send packet via APRS-IS and radio.
+    cycle-size  5m
+    beacon srccall N0CALL-1 via WIDE2-1 file "/dev/shm/aprs.pkt"
+    </beacon>
+
+Note: this configuration has the problem that aprx and weewx are not
+syncronized, so aprx may send out the same packet twice or miss one from time
+to time.
+
+
+[1] http://www.weewx.com/
+[2] http://thelifeofkenneth.com/aprx/