---
title: Building an Example
description: Building an example application with RIOT
---

import Contact from '@components/contact.astro';

<Contact />

:::note
This guide uses the `samr21-xpro` board as an example.
You can replace it with the name of any other supported board,
as learned in the previous section, by replacing `samr21-xpro`
with the name of your board.
:::

RIOT provides a number of examples in the `examples/` directory. Every example
has a README that documents its usage and its purpose. You can build them by
opening a shell, navigating to an example (e.g. `examples/basic/default`), and
running:

```bash
make BOARD=samr21-xpro
```

or

```bash
make all BOARD=samr21-xpro
```

To flash the application to a board just run:

```bash
make flash BOARD=samr21-xpro
```

You can then access the board via the serial interface:

```bash
make term BOARD=samr21-xpro
```

If you are using multiple boards you can use the `PORT` macro to specify the
serial interface:

```bash
make term BOARD=samr21-xpro PORT=/dev/ttyACM1
```

For flashing and accessing the board via the serial interface, the current user
needs to have the correct access rights on the serial device.
The easiest way to ensure this is to add the current user to the group that is
owning the serial device. For example, this can be achieved on Linux by issuing
the following line, logging out and logging in again:

```bash
sudo usermod -aG $(stat --format="%G" /dev/ttyACM0) $USER
```

Note that the `PORT` macro has a slightly different semantic in `native`. Here
it is used to provide the name of the TAP interface you want to use for the
virtualized networking capabilities of RIOT.

We use `pyterm` as the default terminal application. It is shipped with RIOT in
the `dist/tools/pyterm/` directory. If you choose to use another terminal
program you can set `TERMPROG` (and if need be the `TERMFLAGS`) macros:

```bash
make -C examples/networking/gnrc/gnrc_networking/ term \
    BOARD=samr21-xpro \
    TERMPROG=gtkterm \
    TERMFLAGS="-s 115200 -p /dev/ttyACM0 -e"
```

You may not see the greeting

```plaintext title="The greeting message from the board"
main(): This is RIOT!
```

when you flash the board. In this case, type `reboot` in the command line or reboot manually.

:::tip[Using the native port with networking]
If you compile RIOT for the native cpu and include the `netdev_tap` module,
you can specify a network interface like this: `PORT=tap0 make term`

*Setting up a tap network*

There is a shell script in `RIOT/dist/tools/tapsetup` called `tapsetup` which
you can use to create a network of tap interfaces.

*USAGE*

To create a bridge and two (or `count` at your option) tap interfaces:
```shell
    sudo ./dist/tools/tapsetup/tapsetup [-c [<count>]]
```

A detailed example can be found in `examples/networking/gnrc/gnrc_networking`.
:::