# Air Sensor Project

by johnb1003 | | 147 views | 3 comments | 24 Oct 19:26

Disclaimer: This project is still a work in progress! I adopted the project from a group of undergrad students that previously attended UMass Amherst and have since graduated. The function of this particular air sensor is to take measurements of air temperature, humidity, and dust particulate (in parts-per million). Here is a link for the sensor I was handed last year:

https://b-z-l.github.io/Bottle-Sensor/SOP

Originally, the sensor would take these measurements and write the data to a SD card. What I am attempting to add to this project is to give it the ability to transmit real time data to a website, as well as visualizing the data through plotting it on a graph. To do this, I am reassembling the sensor using an ESP8266 wifi shield instead of the Arduino Pro Micro so that it can connect to wifi. In addition, I have set up a Thingspeak.com account which receives the data transmitted from the sensor and plots it automatically.

So far, I have run into a few problems. The first being that the ESP8266 has digital input pins that only allow an input of 0-1V which differs from the Arduino input pins. To overcome this I had to add a resistor into the circuit between the 5V and the output of the DHT22 temperature and humidity sensor. Now, I am approaching a similar problem with the dust sensor. I am having trouble deciding the magnitude of the resistor I need to place between the 5V and output pin of the Shinyei PPD42NJ Dust Sensor.

Ooh, i love the very succinct bill of materials with links and prices! Great documentation! Did you write that documentation? Copying it in here for ease of reading:

## Bill of Materials

Item Cost (USD) Source
Shinyei PPD42NJ Dust Sensor $10 Aliexpress or Ebay DHT22 Temperature Humidity Sensor$3 Aliexpress
Arduino Pro Micro, ATMega32U4-5V 16Mhz $4 Ebay Mini Datalogger with microSD card reader and RTC$4 Ebay
MicroSD Card $5 Ebay Datalogger/Screw Terminal Adapter$6
Plastic Chassis, 3D printed $6 USB Charger$6 Digikey or Sparkfun
#4-40 3/8" Self-Tapping Screws $1 Link USB Battery$30 Ebay
Total $75 Total w/o battery or USB charger$39

Note: The Shinyei PPD42 is sensitive to small fluctuations in voltage. Because the quality of USB chargers vary widely it is recommended to use a USB battery or charger from a major manufacturer. See here for more information on USB charger quality.

https://github.com/b-z-l/Bottle-Sensor/blob/master/docs/SOP.md

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