A quick reference for the buses and headers you wire up most often.
Works offline · runs entirely on your device
A quick reference only — always confirm against the datasheet for your exact board and module.
Two-wire addressable bus — many devices share the same 2 lines.
| Signal | What it does |
|---|---|
| SDA | Serial data (bidirectional) |
| SCL | Serial clock (from the controller) |
| VCC | Power — 3.3V or 5V |
| GND | Ground / common reference |
Fast four-wire bus — one chip-select line per peripheral.
| Signal | What it does |
|---|---|
| SCLK | Serial clock (from the controller) |
| MOSI | Controller out, peripheral in |
| MISO | Controller in, peripheral out |
| CS / SS | Chip select (active low) |
Point-to-point async serial — cross TX and RX.
| Signal | What it does |
|---|---|
| TX | Transmit — connects to the other side's RX |
| RX | Receive — connects to the other side's TX |
| GND | Common ground (required) |
| VCC | Optional power for the module |
Common ultrasonic distance-sensor 4-pin header.
| Signal | What it does |
|---|---|
| VCC | 5V power |
| Trig | Trigger input — pulse to start a measurement |
| Echo | Echo output — pulse width = distance |
| GND | Ground |
Standard 3-wire hobby-servo connector.
| Signal | What it does |
|---|---|
| Signal | PWM control (orange / white) |
| VCC | Power, 4.8–6V (red) |
| GND | Ground (brown / black) |
Boards whose full pinouts you can view: