Ble door sensor

homesensors / hardware / door_sensor

KiCad project for the homesensors BLE door sensor — a custom small PCB with STM32WB09KEVx + TCS40DPR Hall sensor + active-low LED + CR2032 holder. Part of the homesensors DIY smart-home sensor kit, and the first fabricated board in the hardware repo's board family.

Revisions

The older tag names pcb-rev-a / pcb-rev-b still exist as aliases pointing at the same commits — those were the door-sensor-only tags from before the hardware repo grew to host multiple board projects. New tags use the door_sensor-rev-* namespace going forward.

Check out a specific revision:

git checkout door_sensor-rev-a   # or -rev-b

What's in the repo

Quick fab

1. Tag: git checkout door_sensor-rev-a (or whichever rev you want).
2. Open ble_door_sensor.kicad_pro in KiCad 7+.
3. PCB Editor → File → Plot → Gerber + drill files → submit to JLCPCB / PCBWay / OSH Park / Aisler.
4. BOM: use ble_door_sensor.csv with the LCSC part numbers; most fabs will assemble in-house from this BOM directly.

The PCB is hand-solderable at 0603 / 0805 sizes but the WB09KEVx in QFN32 is best assembled by the fab.

Design notes

• MCU: STM32WB09KEVx (QFN32). On-chip 2.4 GHz BLE.
• Sensor: Toshiba TCS40DPR Hall (active-low, single-ended). Magnet absent = sensor reads 1 = door open.
• LED: active-low, push-pull, on PA1, with a 510 Ω series resistor.
• BLE matching: 20 pF series cap → MLPF-NRG-01D3 → 50 Ω microstrip → chip antenna (Johanson 2450AT18A0100E or compatible).
• Battery monitor: external divider 1 MΩ / 1 MΩ + 1 µF X7R, midpoint into PB1 = ADC1_VINP1. Quiescent current ~1.5 µA. (Rev B; hand-soldered on Rev A.)
• VDDA_VCAP: 0.22 µF decoupling on pin 28. (Rev B; hand-soldered on Rev A.)
• HSE crystal: 32 MHz. Firmware sets XTAL_StartupTime to 800 µs.

For the long-form design history, including the bring-up gotchas (PB3 JTDO default pull-up, ADC sample-and-hold droop with too-small reservoir cap), see the firmware repo's HANDOVER.md at homesensors/firmware.

Bring-up / known-good checks

After fabricating a new board:

1. Visual / DMM: check VDDA_VCAP cap (pin 28) is populated, no solder bridges around the QFN32, divider resistors read ~1 MΩ each.
2. Power-on: cell + LED behaviour matches spec — LED blinks at ~1 Hz heartbeat in boot phase when magnet absent.
3. BLE smoke: with nRF Connect or bluetoothctl scan on, the device should appear with service-data UUID 0xFCD2. Service data byte sequence starts with 44 00 ….
4. HA discovery: HA's BTHome integration auto-discovers the device within seconds. Confirm an entity tree with opening, battery, packet_id, timestamp.

License

CERN-OHL-P-2.0 — see LICENSE at the hardware-repo root. Permissive open hardware: fork the design, fab it, sell physical units, no copyleft strings. Just preserve the licence + notices.

Related repos

• homesensors/sensorkit — umbrella, protocol spec, build guide.
• homesensors/firmware — STM32WB09 firmware.
• homesensors/homeassist — HA add-on.