# Chapter 13: Walking a Quadruped

## Sample code

- Directory: `docs/os-on-arduino/code/13_quadruped`

```bash
uv run pio run -d 13_quadruped -t upload
uv run pio device monitor -b 115200
```

## Source code

The sketch for this chapter. Click a file name to expand. The code is mirrored automatically from the manuscript repository, so what you see here is always current.

:::{dropdown} `src/main.cpp` — 203 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/src/main.cpp)

```{literalinclude} ../../../../code/13_quadruped/src/main.cpp
:language: cpp
:linenos:
```

:::

:::{dropdown} `include/arduino_quad_policy.h` — 81 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/include/arduino_quad_policy.h)

```{literalinclude} ../../../../code/13_quadruped/include/arduino_quad_policy.h
:language: cpp
:linenos:
```

:::

:::{dropdown} `include/leg_ik.h` — 13 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/include/leg_ik.h)

```{literalinclude} ../../../../code/13_quadruped/include/leg_ik.h
:language: cpp
:linenos:
```

:::

:::{dropdown} `include/quad_calib.h` — 26 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/include/quad_calib.h)

```{literalinclude} ../../../../code/13_quadruped/include/quad_calib.h
:language: cpp
:linenos:
```

:::

:::{dropdown} `include/quad_control.h` — 187 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/include/quad_control.h)

```{literalinclude} ../../../../code/13_quadruped/include/quad_control.h
:language: cpp
:linenos:
```

:::

:::{dropdown} `include/servo_bus.h` — 24 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/include/servo_bus.h)

```{literalinclude} ../../../../code/13_quadruped/include/servo_bus.h
:language: cpp
:linenos:
```

:::

:::{dropdown} `src/gait.cpp` — 56 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/src/gait.cpp)

```{literalinclude} ../../../../code/13_quadruped/src/gait.cpp
:language: cpp
:linenos:
```

:::

:::{dropdown} `src/leg_ik.cpp` — 44 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/src/leg_ik.cpp)

```{literalinclude} ../../../../code/13_quadruped/src/leg_ik.cpp
:language: cpp
:linenos:
```

:::

:::{dropdown} `src/leg_ik_test.cpp` — 33 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/src/leg_ik_test.cpp)

```{literalinclude} ../../../../code/13_quadruped/src/leg_ik_test.cpp
:language: cpp
:linenos:
```

:::

:::{dropdown} `src/servo_bus.cpp` — 176 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/13_quadruped/src/servo_bus.cpp)

```{literalinclude} ../../../../code/13_quadruped/src/servo_bus.cpp
:language: cpp
:linenos:
```

:::

## On the board

```{figure} ../_static/quadruped_walk.gif
:name: fig-ch13-walk
:width: 80%

The quadruped walking on your own OS, driving 8 servos (1.5x speed)
```

## Pitfalls

(Collected from reader questions — ask via
[GitHub Issues](https://github.com/iory/build-your-own-arduino-rtos/issues).)