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