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Clarify DCMotor sample pin numbering and H-bridge wiring #2583

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Clarify DCMotor sample pin numbering and H-bridge wiring #2583

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9329a1f
Initial plan
Copilot Jul 1, 2026
65a52d8
Clarify DCMotor sample pin numbering and H-bridge wiring
Copilot Jul 1, 2026
d777123
Address review: add pinout link and use bullet list in wiring docs
Copilot Jul 1, 2026
98167b3
Use GPIOxx naming and add H-bridge pin numbers in DCMotor wiring docs
Copilot Jul 1, 2026
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22 changes: 22 additions & 0 deletions src/devices/DCMotor/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@ static void Main(string[] args)
// using (DCMotor motor = DCMotor.Create(PwmChannel.Create(0, 0, frequency: 50), 23, 24))
// Start Stop mode - wrapper with additional methods to disable/enable output regardless of the Speed value
// using (DCMotorWithStartStop motor = new DCMotorWithStartStop(DCMotor.Create( _any version above_ )))
// Pin numbers use the logical (BCM) numbering scheme (GPIOxx). See the Wiring section below.
// 3 pin mode: GPIO6 -> ENA (pin 6, enable/PWM), GPIO27 -> IN1 (pin 5), GPIO22 -> IN2 (pin 7) on the H-bridge.
using (DCMotor motor = DCMotor.Create(6, 27, 22))
{
bool done = false;
Expand Down Expand Up @@ -66,6 +68,26 @@ static void Main(string[] args)
}
```

## Wiring

All pin numbers passed to `DCMotor.Create` use the **logical (BCM/Broadcom)** GPIO numbering scheme (referred to as `GPIOxx`, e.g. `GPIO6`), not the physical header positions. See the [Raspberry Pi GPIO pinout](https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#gpio) to map `GPIOxx` numbers to physical pins.

The 3-pin sample `DCMotor.Create(6, 27, 22)` connects to an H-bridge (e.g. the L298 IC) as follows:

| `Create` argument | Raspberry Pi pin | H-bridge input (pin) | Purpose |
| ----------------- | ---------------- | -------------------- | ------- |
| `speedControlPin` | GPIO6 | ENA (pin 6) | PWM speed control |
| `directionPin` | GPIO27 | IN1 (pin 5) | Motor direction |
| `otherDirectionPin` | GPIO22 | IN2 (pin 7) | Opposite of IN1 |
Comment on lines +77 to +81

The rest of the wiring:

- The H-bridge outputs drive the motor.
- The motor power supply connects to the H-bridge (never directly to the board).
- The board and H-bridge grounds are connected together.

See the diagram below.

![schematics](./dcmotor_bb.png)

![BiDirectional Pin schematics](./DCMotor2pinWithBiDirectionalPin_bb.png)
2 changes: 2 additions & 0 deletions src/devices/DCMotor/samples/Program.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@
// using (DCMotor motor = DCMotor.Create(PwmChannel.Create(0, 0, frequency: 50), 23, 24))
// Start Stop mode - additional methods to disable/enable output regardless of the Speed value
// using (DCMotorWithStartStop motor = new DCMotorWithStartStop(DCMotor.Create( _any version above_ )))
// Pin numbers use the logical (BCM) numbering scheme (GPIOxx). See README.md for wiring details.
// 3 pin mode: GPIO6 -> ENA (pin 6, enable/PWM), GPIO27 -> IN1 (pin 5), GPIO22 -> IN2 (pin 7) on the H-bridge.
Comment on lines +27 to +28
using DCMotor motor = DCMotor.Create(6, 27, 22);
bool done = false;
Console.CancelKeyPress += (o, e) =>
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