Particle

particle: A Particulate Matter Sensor

particle is an ESP32-C6-based particulate matter sensor. It measures PM1.0, PM2.5, and PM10, displays the latest measurements locally via an e-paper display, and can send them to a paired AQM (air quality monitor) over Bluetooth Low Energy (BLE). The AQM is the Matter-connected device. This device acts as its PM sensor peripheral and does not commission itself as a separate Matter device.

Hardware

• MCU: Seeed Studio XIAO ESP32-C6
• Particulate sensor: DFRobot Fermion BMV080, connected over SPI and driven with the SparkFun BMV080 Arduino library
• Display: 2.13", 250 x 122 pixel monochrome e-paper display using the GDEY0213B74 panel/SSD1680 driver, driven with GxEPD2 and Adafruit GFX
• PCB Custom particle PCB, can be found in /KICAD directory

Operating modes

Standalone / Normal Operation

The PM sensor starts collecting data even when no AQM is available. It polls the BMV080 for new output approximately every 500 ms and forms one-minute averages. Measurements that are obstructed or outside the valid range are not included in the average. When all samples in an interval indicate obstruction, the display shows an obstructed status on the screen instead of a numerical reading.

Standalone operation does not require BLE or a network connection. The first boot makes one automatic attempt to pair with an AQM; the attempt ends after 2 minutes have elapsed, then the device runs standalone until pairing is explicitly requested again with the pairing button or a factory reset.

Note! Device takes a full minute from seeing the particle, Pairing Successful, or Pairing Timed Out screen to transition into displaying values on the EPD. This is due to the sensor having an initialization period.

Linked to an AQM

The PM sensor pairs with the companion Matter AQM over BLE. The AQM supplies the measurement schedule and its RTC time; the PM sensor sends its one-minute PM averages to the AQM when a BLE connection and notification subscription are available. The AQM can then use the readings in its air-quality matter cluster data. The PM sensor continues to take and display local readings if the AQM is temporarily disconnected.

Pairing is initiated automatically on the first boot. Put the AQM into its corresponding PM-pairing mode while the PM sensor displays its pairing screen. The pairing window lasts up to 120 seconds. On success, the peer is saved in non-volatile storage and the PM sensor will try to reconnect to that AQM on subsequent boots. If pairing times out, the PM sensor continues in standalone mode; hold the pairing button for one second during a later boot to try again.

Buttons

Both buttons are checked at boot. Hold the pairing button for at least one second to enter AQM pairing mode. Hold the factory reset for at least one second, then release, to factory reset.

Build, upload, and serial output

Install PlatformIO and the Espressif platform dependencies, connect the XIAO ESP32-C6, then run these commands from the project directory:

pio run -e esp32c6
pio run -e esp32c6 -t upload
pio device monitor -b 115200

The PlatformIO environment is defined in platformio.ini. The project uses the Arduino and ESP-IDF frameworks and is configured for the seeed_xiao_esp32c6 board. Serial diagnostics run at 115200 baud. Upload port selection may need to be configured for the host computer.

Project layout

main/                  Firmware source, display assets, and project component config
  font/                Embedded Adafruit GFX fonts
lib/                   Project-local libraries (including modified GxEPD2 and BMV080 libs)
managed_components/    ESP-IDF managed components
KICAD/                 PCB and schematic design files
2D/                    Drawings
3D/                    Board, component, and enclosure models
UI/                    Display/UI mockups and PCB graphics
.vscode/               VS Code project configuration
platformio.ini         PlatformIO build environment
sdkconfig.defaults.*   ESP-IDF default configuration for the target
huge_app.csv           ESP-IDF flash partition table
dependencies.lock      Locked ESP-IDF component dependencies

The primary firmware files are:

• main/main.cpp: boot behavior, button handling, sensor sampling, averaging, and the main loop
• main/sensor.cpp: BMV080 initialization and reading validation
• main/screen.cpp: e-paper initialization, measurement display, and status screens
• main/pm_link.cpp: BLE pairing, reconnection, timing, and PM-reading transfer
• main/pm_protocol.h: BLE data structures shared with the companion AQM project