Air Quality Box v0.1

First release of the Air Quality Box. Main features:

• Warm up dust sensor period of 1 minute at the beginning
• Measures every 5 minutes and a buffer of 60 measurements so 5h measurements storage
• Show average for all the buffer on upper side of the screen with color representation
• Touchscreen reactive switching on and off on touch, to save energy
• 2 particle sizes, PM10 and PM25, under measurement, showing their concentration and individual AQI
• Lower part of the screen with the global AQI measured for the last 5 minutes

This sketch is supposed to be used on an Arduino Mega with a DSM501 dust sensor connected to digital pins 30 and 40, and an Adafruit TFT touchScreen with ILI9341 and STMPE610 chips plugged. The DSM501 must be properly placed in it's enclosure isolating it from external light and ensuring it's vertically placed with both air input and output in the lower and upper side of the enclosure. Measurements under 100 ug/m3 are supposed to contain very high error margins (up to 50%) while error in upper dust measurements is much lower (up to 25%). These measurements are not yet adjusted taking into account the altitude of the measurement point.