import serial
import struct
import binascii
# import pyb
from binascii import hexlify
import time

ser = serial.Serial(
    port='COM6',
    baudrate=9600,
    parity=serial.PARITY_NONE,
    stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS
)
#11 02 0B 01 E1
while 1:

    buf = bytearray(19)
    mv = memoryview(buf)
    idx = 0
    #polling the sensor
    ser.write(serial.to_bytes([0x11, 0x02, 0x0b, 0x01, 0xE1]))
    while idx < len(buf):
        if ser.read():
            bytes_read = ser.readinto(mv[idx:])
            # print('Got {} bytes of data'.format(bytes_read), hexlify(buf[idx:idx+bytes_read], b':'))
            idx += bytes_read
    # print('Final buffer =', hexlify(buf, ':'))
    headerValid = False
    #((buf[0] == 0x16) and (buf[1] == 0x11) and (buf[2] == 0x0B))
    #Bug if sensor polling is active: Missing first byte "0x16", maybe because of bad hardware.
    if ((buf[0] == 0x11) and (buf[1] == 0x0B)):  headerValid = True
    if (headerValid==True):
        pm25 = buf[4] * 256  + buf[5]   #PM2.5(μg/m³)= DF3*256+DF4
        pm1 = buf[8]*256^1 + buf[9]     #DF7*256^1 + DF8
        pm10 = buf[12]+256^1 + buf[13]  #DF11*256^1 + DF12
        print('=======================================')
        # print('Received PM 1.0 reading: ', pm1, 'μg/m³') #Wrong sensor?!
        print('Received PM 2.5 reading: ', pm25, 'μg/m³')
        # print('Received PM 10 reading:  ', pm10, 'μg/m³') #Wrong sensor?!
    time.sleep(8)