This meter measures dust (pm1, pm2.5, pm10 particles) and, optionally, other environmental conditions like temperature, pressure and humidity. Measurements occurs in configured intervals and the result is an average of multiple recorded samples. It handles 'warming period' necessary by the sensor to force proper air flow.
Current air quality is indicated with different color of RGB led (blue color means that first measurement has not completed yet).
Data is sent via local wifi to one of configured services (currently - ThingSpeak, AWS IoT is coming soon). After booting up for the first time, sensor becomes an access point and enables user to configure wifi access via browser.
Required parts:
ESP32 DevKit Board (other boards should also work after minor modifications). Plantower PMS5003 (or PMS3003 or PMS7003) Any push button
Optional parts:
BMP280 sensor for temperature/airpressure readings RGB Led (common kathode) + 3 resistors (330ohms+)
Here. I draw it myself.
Assembling is rather trivial.
PMSx003 sensor requires 5V power, although it communicates with standard 3V3, so no TTL converter is required. Connect RGB led via resistors to ESP32 and to GND. Connect BMP280 directly to ESP32. Connect button to one of pins to pull up when pressed.
ESP32 chip features GPIO matrix which means (theoretically) that programmatically we can change a function of any I/O pin. That being said, on ESP32 DevKit board some pins are already designated to perform specific function and may not work properly (or cause side effects) when assigned to other interfaces.
Firmware is pre-configured to use following GPIO which were tested with ESP32 DevKit board.
These assignments can be changed via 'make menuconfig'.
PMSx003 TX => 34
PMSx003 SET => 10
BMx280 SDA => 25
BMx280 SCL => 26
LED R => 12
LED G => 27
LED B => 14
BUTTON => 35
Sensor requires 5V+ and consumes ~150mA up to ~170mA. During booting power consumption can be slightly higher (~250mA), but it is still low enough to be powered directly from any decent USB phone charger or from PC.
Despite low voltage, if you are going to use sensor outdoor or in any unfriendly environment (e.g. high humidity), please take it under consideration during build, isolate all connections properly and use appropriate case/enclosure (more on that soon).
Firmware is written in native espressif-sdk v2.1 [http://esp-idf.readthedocs.io/en/v2.1/get-started/index.html] After installing and setting up SDK, connect your ESP32 board to your PC. This may require installing custom USB driver (it depends on uart chipset used on your ESP32 board, for DevKit it should be Silabs chip - [http://www.silabs.com/products/mcu/pages/usbtouartbridgevcpdrivers.aspx]).
To configure and build sources
make -j5
You can always bring up configuration menu via
make menuconfig
During the first run, a menuconfig should appear where you need to configure some parameters of your setup, most notably - UART port (in my case - "/dev/tty.SLAB_USBtoUART").
In components submenu there's a few configuration settings related to OAP hardware setup (e.g. gpio pin assignments), and "OAP Main" menu where you can change various functional parameters.
** ATTENTION. main task stack should be increased to 10K if you're gonna use AWSIoT (via menuconfig) **
All settings are saved in sdkconfig file.
to flash the module and read from the serial output
make flash monitor
That's it.
After booting the sensor for the first time, it will switch into Access Point mode and be visible as
ssid: OpenAirProject-XXXX
pass: cleanair //configurable via menuconfig
After connecting to this network, open following url
http://192.168.1.1
and configure sensor settings using web control panel (most notably - your home wifi ssid/pass). After rebooting sensor will connect to your wifi. Web control panel will still be available, but at IP that was specified or assigned to sensor by your router.
If there's a need to force sensor into Access Point mode again (e.g. when it can't connect to specified wifi), reboot the device with a control button pressed down.
Happy DIY time!
