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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. See the Wiring section below.
// 3 pin mode: 6 -> ENA (enable/PWM), 27 -> IN1, 22 -> IN2 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, not the physical header positions. See the [Raspberry Pi GPIO pinout](https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#gpio) to map BCM numbers to physical pins.

The 3-pin sample `DCMotor.Create(6, 27, 22)` connects to an H-bridge (e.g. L298N) as follows:

@raffaeler raffaeler Jul 1, 2026

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@copilot I would rather prefer that you mention explictly the rpi ping as GPIOxx. It is also better if you print the H-bridge pin numbers, in addition to the pin name

@raffaeler raffaeler Jul 1, 2026

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@copilot address this review

Copilot AI Jul 1, 2026

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Done in 98167b3. The Wiring table now uses explicit GPIOxx names for the Raspberry Pi pins (GPIO6/GPIO27/GPIO22) and lists the H-bridge input pin numbers alongside the names (ENA pin 6, IN1 pin 5, IN2 pin 7 on the L298). The sample comments were updated to match.


| `Create` argument | BCM pin | H-bridge input | Purpose |
| ----------------- | ------- | -------------- | ------- |
| `speedControlPin` | 6 | ENA (enable) | PWM speed control |
| `directionPin` | 27 | IN1 | Motor direction |
| `otherDirectionPin` | 22 | IN2 | Opposite of IN1 |

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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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. See README.md for wiring details.
// 3 pin mode: 6 -> ENA (enable/PWM), 27 -> IN1, 22 -> IN2 on the H-bridge.
using DCMotor motor = DCMotor.Create(6, 27, 22);
bool done = false;
Console.CancelKeyPress += (o, e) =>
Expand Down