/**
@defgroup    boards_arduino-nano Arduino Nano
@ingroup     boards
@brief       Support for the Arduino Nano board

## Overview

The Arduino Nano is the cheapest member of the Arduino family. It is based on
Atmel's AVR architecture and sports an ATmega328p MCU. It is like many Arduinos
extensible by using shields.

### MCU
| MCU           | ATmega328p                                    |
|:------------- |:--------------------------------------------- |
| Family        | AVR/ATmega                                    |
| Vendor        | Atmel                                         |
| RAM           | 2 KiB                                         |
| Flash         | 32 KiB (2 KiB reserved for the bootloader)    |
| Frequency     | 16 MHz                                        |
| Timers        | 3 (2x 8bit, 1x 16bit)                         |
| ADCs          | 6 analog input pins                           |
| UARTs         | 1                                             |
| SPIs          | 1                                             |
| I2Cs          | 1 (called TWI)                                |
| Vcc           | 5.0V                                          |
| MCU Datasheet | [ATmega328p datasheet](http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf) |
| Board Manual  | [Board Manual](https://www.arduino.cc/en/uploads/Main/ArduinoNanoManual23.pdf) |

## Flashing the Device
Flashing RIOT on the Arduino Nano is quite straight forward, just connect your
Arduino Nano via the USB connector to your host computer and type:

`make BOARD=arduino-nano flash`

This should take care of everything!

We use the open `avrdude` tool to write the new code into the ATmega328p's
flash

## Using Optiboot

You can use the [Optiboot](https://github.com/Optiboot/optiboot) bootloader
instead of the stock bootloader for faster programming. Optiboot also is
smaller (512 byte instead of 2 KiB), so that 1.5 KiB more program memory is
available for RIOT. Refer to the project page for instructions on how to
build an flash the bootloader. Don't forgot to also update the fuse settings
to set the bootloader size to 256 words (512 bytes).

Compile and flash with `make BOARD=arduino-nano BOOTLOADER=optiboot flash` or
use `export ARDUINO_NANO_BOOTLOADER=optiboot` in order to not have to specify
the bootloader during compilation and flashing.

## Issues

### RIOT Stuck in Reboot Loop

If RIOT is stuck in a reboot loop e.g. after restarting the device with the
`reboot` shell command, this is likely caused by an
[issue with the stock bootloader](https://forum.arduino.cc/index.php?topic=150419.0)
that can be solved by using Optiboot as bootloader instead (see above).

## Caution
Don't expect having a working network stack due to very limited resources.
 */