WheeCAIR

Cullowhee Clean Air Sensor

Hardware

Table S.1: Bill of Materials for wheeCAIR sensor

Item	PN	Price	Qty	Supplier
Sensor, BME 680	1597-1653-ND	$20.910	1	digikey
Sensor, PM, Honeywell	785-HPMA115SO-XXX	$26.340	1	mouser
Micro SD	SDSDQM-B35A	$4.500	1	Amazon
Teensy 3.5	1568-1443-ND	$26.250	1	digikey
USB Cable	WM25438-ND	$3.710	1	digikey
Case	Lowes	$7.150	1	Lowes
Case Port	Lowes	$1.690	0.5	Lowes
Breadboard	1738-1326-ND	$2.990	1	digikey
Wire, Hookup, Assortment, 10x25'	485-3174	$29.950	0.1	mouser
Pin headers, Breakaway, 36 position, 0.1"	WM50014-36-ND	$0.901	2	digikey
LED, RGB	1830-1014-ND	$0.829	1	digikey
Resistor, 220 ohm	CF12JT220RCT-ND	$0.072	1	digikey
Thermistor	BC2301-ND	$0.660	1	digikey
Resistor, 1k	S1KQTR-ND	$0.004	1	digikey
Capacitor, Electrolytic, 1000uF	P19639TB-ND	$0.310	1	digikey
Relay	TLP222AF-ND	$1.013	1	digikey
Header, 5 Position, 0.1	S6103-ND	$0.443	1	digikey
Header, 24 Position, 0.1	S7022-ND	$1.244	2	digikey
Retainer, Coin Cell, 12 MM, SMD	36-3000CT-ND	$0.767	1	digikey
Terminal, 4 Position, 3.5 mm	WM7860-ND	$1.121	2	digikey
Terminal, 2 Position, 3.5 mm	WM7877-ND	$0.718	1	digikey
Batteries, AA, Duracell Procell, 2900 mAh	PC1500BKD	$0.520	6	Grainger
Batteries, Coin Cell, CR1220	P033-ND	$0.828	1	digikey
Wire, PicoBlade, Pre-crimped, black	0500798000-10-B8-ND	$0.676	1	digikey
Wire, PicoBlade, Pre-crimped, yellow	0500798000-10-Y8-ND	$0.676	1	digikey
Wire, PicoBlade, Pre-crimped, red	0500798000-10-R8-ND	$0.676	1	digikey
Wire, PicoBlade, Pre-crimped, violet	0500798000-10-V8-ND	$0.676	1	digikey
PCB, Custom	WheeCAir v1.0 (custom)	$6.820	1	OSH Park

Prices are accurate as of December 2019.

Firmware

The wheeCAIR sensor is programmed using the Arduino IDE and Teensyduino addon (both freely availble). Place the firmware files in a wheeCAIR folder and open wheeCAIR.ino with the Arduino IDE.

Function Descriptions

The following functions are available for programming your sensors. You will need to use all of them, and you might use some twice. Combine them according to the flow chart provided.

Remember, most functions take the form of function(argument);, where the argument is used in completing the function. Some functions do not require an argument, and others require multiple. The arguments are provided below where needed and should be used verbatim.

• alarm.setRtcTimer(0, 0, 0);: Set the hibernation interval on the Teensy in Hours, Minutes, and Seconds.

• createFileName(year(), month(), day()).toCharArray(dataFileName, 16);: Generate a file name following a standard format of YYYYMMDD.txt; this is used to store the data on the SD card.

• initializeSensors();: Turn the sensors on and go through initialization procedure; no argument necessary.

• initializeSDCard();: Start the SD card reader on the Teensy; no argument necessary.

• Serial.Begin(9600);: Start the serial port at 9600 bits per second (baud).

• Serial.println(dataString);: Print the data to the serial port of the computer; useful for debugging.

• Snooze.hibernate(teensySleep);: Put the Teensy into hibernation mode for the time specified in alarm.setRtcTimer(H, M, S);.

• setSyncProvider(getTeensy3Time);: Update/set the time on the Teensy's real time clock (RTC). Must be done after every hibernation.

• String dataString = makeMeasurement(30);: Create a string called dataString, make measurement for n (e.g. 30) seconds, and store the data in dataString.

• turnOffSensors();: Turn the sensors off before hibernating the Teensy; no argument necessary.

• wakeSensors();: Turn on the sensors after hibernating the Teensy; no argument necessary.

• writeFile(dataFileName, dataString);: Stores the dataString from the sensors to the dataFileName file on the SD card.

Data

Directory Structure

The generalized directory structure is:

./data/location-code/year/YYYYMMDD_sensorCode.txt

Directory Map

WheeCAIR
       |----- data
       |         |----- [location] (see codes below)
       |                       |----- [year] > [date_sensorName].txt
       |                                 |   > [location-year].jmd or .jl - Julia data processing code
       |                                 |   > [location-year].html - HTML formatted lab notebook
       |                                 |----- datasheets > datasheets completed at deployment
       |                                 |----- img > Webcam/weather images (if available)
       |                                 |----- met > meteorology data (if available)
       |                                 |----- plots > PDFs of key figures
       |----- firmware > code used program sensors
       |----- hardware > hardware info
       |----- docs > html to serve (notebooks)

Location Codes:

• grsm-purchase: Great Smoky Mountains National Park - Purchase Knob
• mack: Dillsboro, NC
• wcu-nsb: Western Carolina University - Natural Science Building (co-located with PM10 inlet)