Gate sensor v2 assembly

Meshtastic Gate & Door Sensor

Carrier board + firmware that bridges a cheap 433 MHz wireless door sensor onto a private Meshtastic LoRa mesh. A trigger on the door raises an event on the mesh — no WiFi, no cloud, no gateway.

Architecture

KERUI D026 (433 MHz) → RXB6 Receiver → Arduino Nano → UART → Heltec LoRa32 V3 → LoRa mesh

The 433 MHz sensor broadcasts a fixed code on every open/close event. An Arduino Nano decodes the code with rc-switch on D2 (INT0) and forwards a short text line over SoftwareSerial D3 → voltage divider → Heltec GPIO47. The Heltec runs stock Meshtastic with the serial module in TEXTMSG mode at 9600 baud and relays each line into the mesh. A 10 s debounce collapses the KERUI retransmit burst into one mesh event per physical opening.

Firmware emits Gate: TRIGGERED on every event and GATE NODE: Online every 5 minutes as a heartbeat. KERUI D026 sends the same code on open and close, so CODE_CLOSED is disabled by default — one code per event is all you get.

Powered by a Waveshare Solar Power Manager D with 2× 18650 batteries and a 6 V 2 W solar panel. Total draw ≈ 105 mA.

Carrier PCB v2.3

Custom 75×66 mm 2-layer board with:

• Heltec LoRa32 V3 socket (2×18 pins)
• Arduino Nano socket (2×15 pins, 15.24 mm row spacing)
• RXB6 433 MHz receiver (8-pin SIP, direct solder)
• Logic level divider 2.2k / 3.3k (5V → 3.0V on GPIO47)
• Hardening: 10k DE pull-up, 100nF bypass, 100µF bulk
• GND copper pour on both layers
• 0 DRC violations, 34 netlist self-checks pass

Generated programmatically by pcb/gate_sensor_pcb_v2.py and validated with KiCad 10.

Build

Requires Docker (for KiCad CLI) and PlatformIO.

make help            # show all targets

# PCB
make drc             # design rule check
make fab             # export Gerbers + drill for JLCPCB

# Firmware
make build           # compile
make upload          # flash the Nano
make monitor         # 115200 USB serial monitor
make learn-sensor    # discover a new 433 MHz sensor's code

# Heltec Meshtastic flash & configure (stock firmware)
./scripts/flash-heltec-meshtastic.sh           # defaults (auto-detect, EU_868)
./scripts/flash-heltec-meshtastic.sh --help

The flash script downloads the latest stock Meshtastic release, flashes the Heltec V3, applies the gate-sensor config (GPIO47 RX at 9600 baud, TEXTMSG mode, owner name GateSensor/GATE, GPS disabled, Bluetooth disabled) and verifies every setting before closing.

Learning a new sensor

If you're using a different 433 MHz sensor than the KERUI D026, discover its code with:

make learn-sensor

Trigger the sensor a few times and watch for repeating RF unknown: <decimal> lines. Copy the decimal into CODE_OPEN in firmware/include/config.h, re-run make upload, and the sensor will fire Gate: TRIGGERED on the mesh. See docs/learn-sensor.md for details.

Project Structure

├── Makefile                      # build targets (KiCad Docker + PlatformIO)
├── pcb/
│   ├── gate_sensor_pcb_v2.py     # PCB generator script
│   ├── gate_sensor_v2.kicad_pcb  # generated board
│   ├── test_netlist.py           # 34-check PCB self-test
│   ├── generate_assembly.py      # 3D assembly view generator
│   └── logo_silk.json            # raccoon logo silkscreen data
├── firmware/
│   ├── platformio.ini            # PlatformIO config (board=nanoatmega328new)
│   ├── src/main.cpp              # bridge firmware
│   └── include/config.h          # sensor codes, pin defs, timing
├── scripts/
│   └── flash-heltec-meshtastic.sh  # Heltec flash + config
├── docs/
│   ├── schematic.md              # schematic + netlist
│   ├── pcb.md                    # PCB design documentation
│   ├── firmware.md               # firmware documentation
│   ├── assembly.md               # assembly and setup guide
│   ├── learn-sensor.md           # discovering a new 433 MHz sensor code
│   ├── bom.md                    # bill of materials
│   └── ordering.md               # JLCPCB ordering guide
└── pin-outs/                     # component pinout reference images

BOM

~$52 total for one complete sensor node. See docs/bom.md for the full bill of materials.

License

ISC — see LICENSE.