pmsa0003.py

#!/usr/bin/env python3
import collections, datetime, json, serial, sys

Sample = collections.namedtuple('Sample', ['t', 'pm1_ug_m3', 'pm2_5_ug_m3', 'pm10_ug_m3', 'pm1atm_ug_m3', 'pm2_5atm_ug_m3', 'pm_atm_ug_m3', 'pd300nm_dl', 'pd500nm_dl', 'pd1um_dl', 'pd2_5um_dl', 'pd5um_dl', 'pd10um_dl', 'data13_reserved', 'checksum'])

def pmsa003_read_passive(uart):
    while not (uart.read(1) == b'B' and uart.read(1) == b'M'):
        pass
    assert 28 == (uart.read(1)[0] << 8) + uart.read(1)[0] # frame length in bytes
    return Sample(datetime.datetime.now(), *[(uart.read(1)[0] << 8) + uart.read(1)[0] for i in range(14)])

if __name__ == '__main__':
    port = serial.Serial(sys.argv[1], baudrate=9600, timeout=5)
    while True:
        print(json.dumps(pmsa003_read_passive(port)._asdict(), default=str), flush=True)