🔑 iButton Keys
iButton keys allow driver identification through a unique chip.
📦 Specifications
| Parameter | Value |
|---|---|
| Protocol | 1-Wire |
| Unique ID | 64 bits |
| Contact | Stainless steel |
| Durability | 10+ years |
🔌 Connection
The reader has 2 wires: the outer part (the metal ring) is ground, the inner part (the center contact) is the signal.
| Reader part | Signal | Spider IoT | Pin | Color |
|---|---|---|---|---|
| Center contact (inside) | 1-Wire DATA | OW | 4 | Purple |
| Metal ring (outside) | GND | GND | 7 | Black |
The iButton reader connects to the same 1-Wire bus as the temperature sensor.
Swapping the two wires breaks nothing — not the reader, not the key, not the unit — but the unit will not read any key: the 1-Wire line is held low and the key never answers.
If the reader ring also touches vehicle metal, the temperature sensor on the same bus stops working too.
Never connect a reader wire to Pin 8 (+VCC 12/24 V) or to any vehicle positive. In 1-Wire mode Pin 4 goes almost straight to the microcontroller: it does not tolerate 12 V and the input burns out.
The reader takes no power supply: signal and ground only.
✅ Verification
With the key held on the reader:
>QOW00<
ROW00,01234567890ABCDE,00If it returns an error or the ID does not change when the key is presented, check which wire is ground (the one with continuity to the outer ring).
🚗 Applications
- Access control: Only authorized drivers can operate the vehicle
- Trip logging: Identify who drove on each journey
- Security: Engine lockout if valid key is not presented