This video is about using three small computers one of which is a microbit computer to measure and display PM2.5 measurements.
A Seeed Studio Grove - Laser PM2.5 Sensor (HM3301) is used to collect the Particular Matter (PM) results not only for PM2.5 but also for PM1 & PM10. This PM2.5 sensor also has its own computer onboard.
The third computer is a Seeeduino Lotus V1.1 and this is Arduino UNO compatible. The Lotus computer is connected to the Grove PM2.5 sensor via a I2C link and it is connected to the microbit via a UART link. The Lotus computer was programmed in C++ using the Arduino IDE and the code was based on Seeed Studio demos with modifications to add a second UART with a softSerial port and adding the coms protocol to identify PM values.
A key part of this project is getting the link between the microbit and the Lotus computer to work and a communications protocol to identify PM values was developed. The microbit displays the PM values onto a two line LCD and give a warning using colour codes if the PM2.5 measurements are too high. Microsoft Makecode was used to program the microbit. A Bitmaker interface baord was used and it connects to both the Lotus computer and the 2 line LCD. The warning colour code is implemented using BitMakers onboard 4 neopixel LEDs.
Future projects using this sensor are also considered including adding LoRaWAN coms to connect and publish PM2.5 measurements to the internet.
