Adafruit SAMD21 Installation Manual

Installing CircuitPython on SAMD21 Boards

Created by Shawn Hymel

Last updated on 2021-03-05 05:59:27 PM EST

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Guide Contents

Guide Contents Overview Installing the Arduino Board Definition

Install Arduino Add Board Manager URL Install Board Definition Board Definition Packages

Installing the UF2 Bootloader

Windows 7 Drivers Download the UF2 Arduino Installer Upload UF2 with Arduino Learning More About UF2

Installing CircuitPython Caveats for CircuitPython on Non-Express Boards

Download the Latest Version of CircuitPython Start the UF2 Bootloader

Test It! Learning CircuitPython Advanced: Creating Your Own Port

1. Create a UF2 Port

2. Create a CircuitPython Port

3. Test Your Board

4. Create Pull Requests

5. Update Mu (Optional)

Overview

CircuitPython is a programming language based on Python, and it is designed to work with low-cost

microcontroller boards to make learning and tinkering easier. The Microchip ATSAMD21 is an inexpensive

chip with the power to run CircuitPython.

Some SAMD21-based boards, like the Circuit Playground Express (https://adafru.it/wpF), METRO M0

Express (https://adafru.it/xoa), and Feather M0 Express (https://adafru.it/wfb), are designed to work with

CircuitPython out of the box. Others, like the Arduino MKRZero, require a little more work.

This guide will show you how to install CircuitPython on a variety of SAMD21-based boards!

The easiest method for installing CircuitPython is through the UF2 bootloader. UF2 is a slick piece of code

that runs on your microcontroller, and it allows the board to appear as a drive on your computer. From

there, you can simply drag-and-drop the CircuitPython installer! We will need to take the following steps to

install CircuitPython on a SAMD21 board:

Install Arduino and the appropriate board definition

Download the UF2 bootloader Arduino code for your board

Upload the UF2 bootloader code to your board from Arduino

Download the CircuitPython installer for your board

Copy the CircuitPython installer to your board

Test it!

Note that you only need to perform these steps once. Once you have installed CircuitPython on your

board, you write CircuitPython code for it over and over again!

 Not every SAMD21 board is covered in this guide. We try to cover the most popular ones, and

CircuitPython is being updated all the time to support new boards, so keep checking back!

Installing the Arduino Board Definition

There are a couple of ways to install UF2 onto your board. The easiest method is to download the pre-

generated Arduino code and upload it to your board from the Arduino Integrated Development

Environment (IDE).

 The Arduino installation method only works if your board comes pre-loaded with the Arduino

bootloader. If you can upload Arduino programs to your board, then you're in luck! Continue with the

rest of the guide.

If you cannot upload Arduino code to your board (for example, you designed your own board with a

factory-fresh SAMD21 chip), then you will need to install the UF2

.bin

file. This will require an Atmel ICE or

other JTAG programmer.

Install Arduino

If you have not already done so, head to arduino.cc (https://adafru.it/lDg), download, and install the latest

Arduino IDE. Note that this guide was written and tested with Arduino version 1.8.7. If you run into issues

uploading code, you might want to try this specific version.

This guide (https://adafru.it/D3z) will show you how to install the Arduino software, if you need some

assistance.

Add Board Manager URL

Some SAMD21 boards will require additional definition files to be installed. If your board is not found in the

Board Manager

, you will need to tell Arduino where to find more definition files from the Internet.

Open Arduino, and click File > Preferences. To the right of the Additional Boards Manager URLs, click on

the Additional URLs window button .

Take a look at the

Board Definition Packages

table at the end of this page, and locate your board. If you

see a

Package URL

listed, copy it into a new line in this window. If you do not see a

Package URL

listed

next to your board, you can skip this step.

You are welcome to have multiple board manager URLs listed here. Just note that each one needs to be

on a separate line.

Click OK to close the

Additional Boards Manager URLs

window, and click OK once more to close the

Preferences

window.

Install Board Definition

A board definition tells the Arduino IDE how to upload code to your particular board, which pins to use,

etc. Arduino comes with a number of board definitions installed by default, including the Arduino Uno,

Arduino Mega, and Arduino Nano. However, many SAMD21 boards are not supported by default in

Arduino, which means we need to add them.

Click Tools > Board > Boards Manager... This will bring up the

Boards Manager

window.

From the

Board Definition Packages

table below, find your board, and copy the

Package Name

. Search

for this name, and click on the Install button that appears when you hover your mouse over the package's

box.

Once the installation process has completed, click Close to exit the

Board Manager

.

Board Definition Packages

Adafruit Feather M0 Basic Proto (https://adafru.it/s1d)

Package URL:

https://adafruit.github.io/arduino-board-

index/package_adafruit_index.json

Package Name:

Adafruit SAMD Boards

Arduino MKRZero (https://adafru.it/DiY)

Package Name:

Arduino SAMD Boards

SparkFun SAMD21 Dev Breakout (https://adafru.it/DJd)

Package URL:

Click for address (https://adafru.it/D3A)

Package Name:

SparkFun SAMD Boards

SparkFun SAMD21 Mini Breakout (https://adafru.it/DiZ)

Package URL:

Click for address (https://adafru.it/D3A)

Package Name:

SparkFun SAMD Boards

Adafruit SAMD21 Installation Manual

Specifications and Main Features

Frequently Asked Questions

User Manual