Imported from GitHub: Jerzeek/room-pcb · commit 418d232

Description

Room Sensor

README

Room Sensor

An open-source, mains-powered room sensor PCB based on the ESP32-C6. Measures CO2, temperature, humidity, illuminance, and presence, with a WS2812B LED status indicator. Supports both ESPHome (Wi-Fi / Home Assistant) and Zigbee firmware out of the box.

---

WARNING — MAINS AC VOLTAGE

This board connects directly to mains AC (100–240 V). Incorrect wiring or handling can cause electric shock, fire, or death. This project is intended for experienced makers who are comfortable working with mains-voltage electronics. Always work with the power disconnected. Comply with all local electrical codes. The authors accept no liability for any damage or injury.

---

Features

• Direct mains AC input via onboard HLK-5M05 AC-DC converter (no external power brick needed)
• CO2, temperature, and humidity via CozIR sensor (NDIR CO2, UART)
• Ambient light via BH1750 (I2C, lux)
• Secondary temperature + humidity via AHT20 (I2C)
• Presence/occupancy detection via LD2410 mmWave radar (UART)
• Visual CO2 status indicator: 2× WS2812B addressable LEDs
• Polyfuse (F1) overcurrent protection
• Reset/factory-reset button (BOOT pin)
• ESP32-C6 SuperMini module — supports both Wi-Fi 6 and native Zigbee
• Two equal-priority firmware options: ESPHome and Zigbee (Arduino)

Sensors

Sensor	Part	Interface	Measures
CO2 (NDIR)	CozIR	UART (9600 baud)	CO2 (ppm), temperature, humidity
Ambient light	BH1750FVI-TR	I2C (0x23)	Illuminance (lux)
Temperature + humidity	AHT20	I2C	Temperature (°C), humidity (%RH)
Presence / occupancy	LD2410	UART (256000 baud)	Presence, moving/stationary targets
Status LEDs	WS2812B-2020 × 2	GPIO (RMT)	CO2 level indicator

Hardware

Main components

Ref	Part	Description
U5	ESP32-C6 SuperMini	Main MCU — Wi-Fi 6 + Zigbee
PS1	HLK-5M05	AC-DC converter, 100–240 V AC → 5 V DC
U1	CozIR	NDIR CO2 / temp / humidity sensor
U2	BH1750FVI-TR	Ambient light sensor
U3	AHT20	Temperature + humidity sensor
J4	5-pin header (1.27 mm)	LD2410 radar connection
D1, D2	WS2812B-2020	Addressable RGB LEDs
F1	Polyfuse	Overcurrent protection

Versions

Version	Notes
v4.1	Current release — improved silkscreen
v4	Production-ready layout
v3.1	Earlier revision (3D model reference)
v3	Initial working prototype

Building / Ordering

All files needed to order and assemble the PCB are in pcb/production/:

File	Purpose
room-pcb.zip	Gerber + drill files — upload directly to your PCB fab (JLCPCB, PCBWay, etc.)
bom.csv	Bill of materials for component sourcing
positions.csv	Pick-and-place / component placement file
designators.csv	Designator reference
netlist.ipc	IPC-D-356 netlist for electrical testing

KiCad source files are in pcb/.

Firmware

ESPHome (Wi-Fi / Home Assistant)

Configuration is in code/esphome/room_sensor.yaml. A custom ESPHome component for the CozIR sensor is included under code/esphome/components/cozir/.

1. Copy room_sensor.yaml and the components/ directory to your ESPHome config folder.
2. Create a secrets.yaml with your wifi_ssid and wifi_password.
3. Flash via esphome run room_sensor.yaml.

The LED indicates CO2 level:

Color	CO2
Green	< 800 ppm (good)
Yellow	800–1200 ppm (moderate)
Red	> 1200 ppm (poor)

Calibration buttons are exposed to Home Assistant:

• Calibrate Fresh Air (400 ppm) — use outdoors in clean air
• Calibrate Nitrogen (0 ppm) — use with pure N2

Zigbee (Arduino / esp32-arduino)

Sketch is in code/combined_working_zigbee/combined_working_zigbee.ino. Requires the Arduino ESP32 core (≥ 3.x) with Zigbee support.

Before flashing:

• In Arduino IDE → Tools → Zigbee Mode → select Zigbee ED (End Device)
• Select a partition scheme that includes Zigbee (e.g., Zigbee 4MB with spiffs)

The sketch exposes four Zigbee endpoints:

Endpoint	Cluster	Data
10	CO2 (CarbonDioxide)	CO2 ppm
11	Temp + Humidity	Temperature °C, humidity %RH
13	Illuminance	Lux
14	Occupancy	Presence (boolean)

Hold the BOOT button for 3 seconds to perform a Zigbee factory reset.

Repository layout

room-pcb/
├── pcb/                  KiCad project files
│   └── production/       Gerbers, BOM, placement — ready to order
├── code/
│   ├── esphome/          ESPHome YAML + custom CozIR component
│   └── combined_working_zigbee/  Arduino Zigbee sketch
├── 3Dmodels/             STEP model of the enclosure / board
├── CHANGELOG.md
├── CONTRIBUTING.md
└── LICENSE

License

Hardware (PCB and schematics) is licensed under the CERN Open Hardware Licence Version 2 — Strongly Reciprocal (CERN OHL-S v2). See LICENSE for the full text.

Firmware is licensed under the same CERN OHL-S v2 unless a file header states otherwise.