Measuring air quality includes the necessity to determine the amount of dust or particulate matter (PM) in the air. Dust is not so bad but really small particles, 2.5µm and 10µm in diameter, can penetrate the lungs causing all sorts of health problems. The measurement of these particles are often called 2.5PM and 10PM and they are measured in micro-grams per cubic meter of air (µg/m3).
The SDS021 sensor uses laser based light scattering to detect both 2.5µm and 10µm sized particles. It has an integrated fan to maintain constant airflow across the sensing chamber. The sensor does all the internal processing and temperature compensation and outputs both measurements over an easy to use serial interface every second.
A four pin interface cable is included with the sensor. One end of the cable is a 1.25mm pitch connector that connects to the sensor. The opposite connector is a 0.1" pitch polarized connector. We found inserting male jumper wires works best (shown in the photo) but will also work with male headers.
Once power is applied the sensor will start reporting readings every second. Only three connections (5V, GND, RX) are required but if you want to send commands to the module you’ll need a fourth wire (TX). We’ve written a handful of example sketches to demonstrate how to read the 2.5PM and 10PM measurements as well as graph the output and sleeping/waking the module via software to conserve power.
The sensor requires 5V to operate so we recommend using this with a RedBoard, Teensy, or other platform that can provide a good 5V at 60mA. The serial interface is 3.3V so use a logic level converter where needed.
Walking and/or movement of the sensor will cause airflow variations across the sensing chamber but the variance is not estimated to have significant impact on the measurements.
We do not plan to regularly carry SparkX products so get them while they’re hot!
Features:
- Voltage: 5V
- Current: 60mA (laser/fan on), less than 4mA during sleep (laser/fan off)
- Precision: 0.0 to 999.9 µg/m3
- Accuracy: +/- 10µg/m3, +/-15% at upper threshold of 999µg/m3
- Outputs 2.5PM and 10PM readings every second
- Software controlled sleep and wake
Documents:
- SDA021 Datasheet
- Serial Interface Specification
- Example sketches to get your started
- Good Wikipedia article on particulates
