# Chapter 2: Starting from Bare Metal

## Sample code

- Directory: `docs/os-on-arduino/code/02_baremetal`

```bash
uv run pio run -d 02_baremetal -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` — 119 lines
:icon: code

[Open on GitHub](https://github.com/iory/learning-os-from-arduino/blob/main/docs/os-on-arduino/code/02_baremetal/src/main.cpp)

```{literalinclude} ../../../../code/02_baremetal/src/main.cpp
:language: cpp
:linenos:
```

:::


## On the board

The Servo task only computes an angle and prints it; it sends no signal to a servo, so you do not need to connect one.

```{figure} ../_static/ch02_tasks.gif
:name: fig-ch02-tasks
:width: 100%

`Servo angle` moves 10 degrees at a time, with `LED` and `Sensor` in between: the three tasks take turns.
```

## Pitfalls

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