grisu48 · April 10, 2019 09:20 · Jan 24, 2017 · Jan 24, 2017
diff --git a/read_nova_pm_sensor.py b/read_nova_pm_sensor.py
@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+
+"""
+Get reading from Nova PM Sensor SDS011
+(dust sensor, air quality sensor, PM10, PM2,5)
+
+Designed to run from cron and append CSV file.
+
+Script tested using Python3.4 on Ubuntu 14.04.
+
+TODO: choose by dev name using udev, add dev id info, python package pyudev
+    udevadm info -q property --export /dev/ttyUSB0
+"""
+
+import os
+import csv
+import io
+
+import logging
+import datetime
+import argparse
+
+try:
+    import serial
+except ImportError:
+    print('Python serial library required, on Ubuntu/Debian:')
+    print('    apt-get install python-serial python3-serial')
+    raise
+
+
+LOG_FORMAT = '%(asctime)-15s %(levelname)-8s %(message)s'
+
+
+def append_csv(filename, field_names, row_dict):
+    """
+    Create or append one row of data to csv file.
+    """
+    file_exists = os.path.isfile(filename)
+    with io.open(filename, 'a', encoding='utf-8') as csvfile:
+        writer = csv.DictWriter(csvfile,
+                                delimiter=',',
+                                lineterminator='\n',
+                                fieldnames=field_names)
+        if not file_exists:
+            writer.writeheader()
+        writer.writerow(row_dict)
+
+
+def read_nova_dust_sensor(device='/dev/ttyUSB0'):
+    dev = serial.Serial(device, 9600)
+
+    if not dev.isOpen():
+        dev.open()
+
+    msg = dev.read(10)
+    assert msg[0] == ord(b'\xaa')
+    assert msg[1] == ord(b'\xc0')
+    assert msg[9] == ord(b'\xab')
+    pm25 = (msg[3] * 256 + msg[2]) / 10.0
+    pm10 = (msg[5] * 256 + msg[4]) / 10.0
+    checksum = sum(v for v in msg[2:8]) % 256
+    assert checksum == msg[8]
+    return {'PM10': pm10, 'PM2_5': pm25}
+
+
+def main():
+    logging.basicConfig(format=LOG_FORMAT, level=logging.INFO)
+
+    parser = argparse.ArgumentParser(description='Read data from Nova PM sensor.')
+    parser.add_argument('--device', default='/dev/ttyUSB0',
+                        help='Device file of connected by USB RS232 Nova PM sensor')
+    parser.add_argument('--csv', default=None,
+                        help='Append results to csv, you can use year, month, day in format')
+    args = parser.parse_args()
+
+    data = read_nova_dust_sensor(args.device)
+    logging.info('PM10=% 3.1f ug/m^3 PM2.5=% 3.1f ug/m^3', data['PM10'], data['PM2_5'])
+
+    if args.csv:
+        field_list = ['date', 'PM10', 'PM2_5']
+        today = datetime.datetime.today()
+        data['date'] = today.strftime('%Y-%m-%d %H:%M:%S')
+        csv_file = args.csv % {'year': today.year,
+                               'month': '%02d' % today.month,
+                               'day': '%02d' % today.day,
+                               }
+        append_csv(csv_file, field_list, data)
+
+if __name__ == '__main__':
+    main()
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