text: #!/usr/bin/env python3
  
  import requests
  import ST7735
  import time
  from bme280 import BME280
  from pms5003 import PMS5003, ReadTimeoutError
  from subprocess import PIPE, Popen, check_output
  from PIL import Image, ImageDraw, ImageFont
  from fonts.ttf import RobotoMedium as UserFont
  
  try:
      from smbus2 import SMBus
  except ImportError:
      from smbus import SMBus
  
  print("""luftdaten.py - Reads temperature, pressure, humidity,
  PM2.5, and PM10 from Enviro plus and sends data to Luftdaten,
  the citizen science air quality project.
  
  Note: you'll need to register with Luftdaten at:
  https://meine.luftdaten.info/ and enter your Raspberry Pi
  serial number that's displayed on the Enviro plus LCD along
  with the other details before the data appears on the
  Luftdaten map.
  
  Press Ctrl+C to exit!
  
  """)
  
  bus = SMBus(1)
  
  # Create BME280 instance
  bme280 = BME280(i2c_dev=bus)
  
  # Create LCD instance
  disp = ST7735.ST7735(
      port=0,
      cs=1,
      dc=9,
      backlight=12,
      rotation=270,
      spi_speed_hz=10000000
  )
  
  # Initialize display
  disp.begin()
  
  # Create PMS5003 instance
  pms5003 = PMS5003()
  
  
  # Read values from BME280 and PMS5003 and return as dict
  def read_values():
      values = {}
      cpu_temp = get_cpu_temperature()
      raw_temp = bme280.get_temperature()
      comp_temp = raw_temp - ((cpu_temp - raw_temp) / comp_factor)
      values["temperature"] = "{:.2f}".format(comp_temp)
      values["pressure"] = "{:.2f}".format(bme280.get_pressure() * 100)
      values["humidity"] = "{:.2f}".format(bme280.get_humidity())
      try:
          pm_values = pms5003.read()
          values["P2"] = str(pm_values.pm_ug_per_m3(2.5))
          values["P1"] = str(pm_values.pm_ug_per_m3(10))
      except ReadTimeoutError:
          pms5003.reset()
          pm_values = pms5003.read()
          values["P2"] = str(pm_values.pm_ug_per_m3(2.5))
          values["P1"] = str(pm_values.pm_ug_per_m3(10))
      return values
  
  
  # Get CPU temperature to use for compensation
  def get_cpu_temperature():
      process = Popen(['vcgencmd', 'measure_temp'], stdout=PIPE, universal_newlines=True)
      output, _error = process.communicate()
      return float(output[output.index('=') + 1:output.rindex("'")])
  
  
  # Get Raspberry Pi serial number to use as ID
  def get_serial_number():
      with open('/proc/cpuinfo', 'r') as f:
          for line in f:
              if line[0:6] == 'Serial':
                  return line.split(":")[1].strip()
  
  
  # Check for Wi-Fi connection
  def check_wifi():
      if check_output(['hostname', '-I']):
          return True
      else:
          return False
  
  
  # Display Raspberry Pi serial and Wi-Fi status on LCD
  def display_status():
      wifi_status = "connected" if check_wifi() else "disconnected"
      text_colour = (255, 255, 255)
      back_colour = (0, 170, 170) if check_wifi() else (85, 15, 15)
      id = get_serial_number()
      message = "{}\nWi-Fi: {}".format(id, wifi_status)
      img = Image.new('RGB', (WIDTH, HEIGHT), color=(0, 0, 0))
      draw = ImageDraw.Draw(img)
      size_x, size_y = draw.textsize(message, font)
      x = (WIDTH - size_x) / 2
      y = (HEIGHT / 2) - (size_y / 2)
      draw.rectangle((0, 0, 160, 80), back_colour)
      draw.text((x, y), message, font=font, fill=text_colour)
      disp.display(img)
  
  
  def send_to_luftdaten(values, id):
      pm_values = dict(i for i in values.items() if i[0].startswith("P"))
      temp_values = dict(i for i in values.items() if not i[0].startswith("P"))
  
      resp_1 = requests.post("https://api.luftdaten.info/v1/push-sensor-data/",
               json={
                   "software_version": "enviro-plus 0.0.1",
                   "sensordatavalues": [{"value_type": key, "value": val} for
                                        key, val in pm_values.items()]
               },
               headers={
                   "X-PIN":    "1",
                   "X-Sensor": id,
                   "Content-Type": "application/json",
                   "cache-control": "no-cache"
               }
      )
  
      resp_2 = requests.post("https://api.luftdaten.info/v1/push-sensor-data/",
               json={
                   "software_version": "enviro-plus 0.0.1",
                   "sensordatavalues": [{"value_type": key, "value": val} for
                                        key, val in temp_values.items()]
               },
               headers={
                   "X-PIN":    "11",
                   "X-Sensor": id,
                   "Content-Type": "application/json",
                   "cache-control": "no-cache"
               }
      )
  
      if resp_1.ok and resp_2.ok:
          return True
      else:
          return False
  
  
  # Compensation factor for temperature
  comp_factor = 2.25
  
  # Raspberry Pi ID to send to Luftdaten
  id = "raspi-" + get_serial_number()
  
  # Width and height to calculate text position
  WIDTH = disp.width
  HEIGHT = disp.height
  
  # Text settings
  font_size = 16
  font = ImageFont.truetype(UserFont, font_size)
  
  # Display Raspberry Pi serial and Wi-Fi status
  print("Raspberry Pi serial: {}".format(get_serial_number()))
  print("Wi-Fi: {}\n".format("connected" if check_wifi() else "disconnected"))
  
  time_since_update = 0
  update_time = time.time()
  
  # Main loop to read data, display, and send to Luftdaten
  while True:
      try:
          time_since_update = time.time() - update_time
          values = read_values()
          print(values)
          if time_since_update > 145:
              resp = send_to_luftdaten(values, id)
              update_time = time.time()
              print("Response: {}\n".format("ok" if resp else "failed"))
          display_status()
      except Exception as e:
          print(e)
  