Adding new Luftdaten example

diff --git a/examples/luftdaten.py b/examples/luftdaten.py
new file mode 100755 (executable)
index 0000000..2177a56
--- /dev/null
+++ b/examples/luftdaten.py
@@ -0,0 +1,161 @@
+#!/usr/bin/env python
+
+import time
+import json
+import requests
+import ST7735
+from bme280 import BME280
+from pms5003 import PMS5003
+from subprocess import PIPE, Popen, check_output
+from PIL import Image, ImageDraw, ImageFont
+
+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 PMS5003 instance
+pms5003 = PMS5003()
+
+# Create LCD instance
+disp = ST7735.ST7735(
+    port=0,
+    cs=1,
+    dc=9,
+    backlight=12,
+    rotation=270,
+    spi_speed_hz=10000000
+)
+
+# Initialize display
+disp.begin()
+
+# 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())
+    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)
+    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 = 1.2
+
+# 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("fonts/Asap/Asap-Bold.ttf", 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"))
+
+# Main loop to read data, display, and send to Luftdaten
+while True:
+    try:
+        values = read_values()
+        print(values)
+        resp = send_to_luftdaten(values, id)
+        print("Response: {}\n".format("ok" if resp else "failed"))
+        display_status()
+    except Exception as e:
+        print(e)