Add air quality monitoring to your project and with an Adafruit CCS811 Air Quality Sensor Breakout.

This sensor from AMS is a gas sensor that can detect a wide range of Volatile Organic Compounds (VOCs) and is intended for indoor air quality monitoring. When connected to your microcontroller (running our library code) it will return a Total Volatile Organic Compound (TVOC) reading and an equivalent carbon dioxide reading (eCO2) over I2C.

The CCS811 has a 'standard' hot-plate MOX sensor, as well as a small microcontroller that controls power to the plate, reads the analog voltage, and provides an I2C interface to read from.

This part will measure eCO2 (equivalent calculated carbon-dioxide) concentration within a range of 400 to 8192 parts per million (ppm), and TVOC (Total Volatile Organic Compound) concentration within a range of 0 to 1187 parts per billion (ppb). According to the fact sheet it can detect Alcohols, Aldehydes, Ketones, Organic Acids, Amines, Aliphatic and Aromatic Hydrocarbons.

Please note, this sensor, like all VOC/gas sensors, has variability and to get precise measurements you will want to calibrate it against known sources! That said, for general environmental sensors, it will give you a good idea of trends and comparisons. Also, AMS recommends that you run this sensor for 48 hours when you first receive it to "burn it in", and then 20 minutes in the desired mode every time the sensor is in use. This is because the sensitivity levels of the sensor will change during early use. Finally, this chip uses I2C clock stretching, and some microcontrollers/computers don't support that (e.g. Raspberry Pi)

The CCS811 has a configurable interrupt pin that can fire when a conversion is ready and/or when a reading crosses a user-settable threshold. The CCS811 supports multiple drive modes to take a measurement every 1 second, every 10 seconds, every 60 seconds, or every 250 milliseconds.

Nice sensor right? So Adafruit made it easy for you to get right into your next project. The surface-mount sensor is soldered onto a custom made PCB in the STEMMA QT form factor, making them easy to interface with. The STEMMA QT connectors on either side are compatible with the SparkFun Qwiic I2C connectors. This allows you to make solderless connections between your development board and the CCS811 or to chain it with a wide range of other sensors and accessories using a compatible cable. QT Cable is not included, but we have a variety in the shop

For your convenience Adafruit have pick-and-placed the sensor on a PCB with a 3.3V regulator and some level shifting so it can be easily used with your favorite 3.3V or 5V microcontroller.

Please note, an earlier version of this chip supported an on-board thermistor. The sensor has been revised (the chip itself!) to no longer support the thermistor temperature readings. Please use an external temperature sensor and keep to using this one for gas sensing.

Adafruit have also prepared software libraries to get you up and running in Arduino IDE or CircuitPython with just a few lines of code! Check out this tutorial for more information!

Technical Details

• Software libraries, hookup guide, datasheets, schematic, EagleCAD PCB files, and Fritzing available in the product tutorial!
• Uses I2C address 0x5A

Revision History:

• As of Jan 7, 2021 - We've updated this sensor to our 0.7" x 1.0" STEMMA QT standard for sensors. There are now four mounting holes and two STEMMA QT connectors for plug-and-play connectivity! The pinout has changed slightly to be standardized. Functionality is the same otherwise.

CCS881 Datasheet