SAMD21 Mini/Dev Breakout Hookup Guide

Contributors: Jimb0
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Hardware Setup

To power the SAMD21 Breakout board, just plug it into a USB port on your computer. The red power LED indicator should immediately turn on, followed shortly-thereafter by a blinking blue LED on pin 13.

SAMD21 boards plugged in

Windows Driver Installation

After plugging the board in, Windows will try – and fail – to search the Internet for drivers. Click the button below to download the drivers.

Download the SparkFun SAMD21 Windows Drivers

Then follow the steps below to install the drivers:

  1. After downloading, extract the ZIP folder and copy down the location of the sparkfun.inf and files.
  2. Open your Device Manager
    • In Windows 8 or 10, simply search for "Device Manager" and select the Windows app
    • See Window's resources for Windows 7.
    • (Start > Run > "devmgmt.msc", should work on almost any version of the OS.)
  3. In the Device Manager, expand the "Other devices" tree -- you should see an entry for "Unknown Device", Right-click and select Update Driver Software...

  4. Select Browse my computer for driver software. On the next screen
  5. Paste the directory location of your sparkfun.inf and files into the search location. Then hit "Next".
  6. Click "Install" when the next pop-up questions if you want to install the driver.
  7. The driver installation may take a moment, when it's done you should be greeted with a "successfully updated your driver software" message!

Mac and Linux

Mac and Linux users shouldn’t need to download any drivers. The device should show up as a serial port as soon as it’s plugged in to your computer.

Soldering Tips

You can set the SAMD21 Boards up – and start programming them – without connecting anything besides a USB cable, but you’re not going to get far without soldering something to them. That something can be headers (male, female, right-angle or more) or just plain-old wire.

Break Away Headers - Straight

Hook-Up Wire - Assortment (Solid Core, 22 AWG)

Female Headers

Arduino Stackable Header - 6 Pin


If you’re using a Mini Breakout, a pair of 12-pin male headers work well to keep the board breadboard-friendly. A 2-pin female header can be soldered to the inner I2C pins – though you may have to trim the bottom side of the shroud to avoid the ATSAMD21’s pins.

SAMD21 Mini Board assembled

SAMD21 Mini Breakouts assembled with male headers and 6-pin stackable headers. Female headers have to be trimmed a bit to avoid components.

Two pairs of 6-pin stackable headers can also maintain breadboard-compatibility while allowing your to jumper straight out of the board. To use these headers, you’ll have to shave a bit of the bottom edge of the shroud to avoid bumping up against the outer LEDs.

If you’re using the Dev Breakout, you can keep it Arduino-shield-compatible by soldering a handful of female headers into the 6-, 8-, and 10-pin headers. Then solder some 3-pin male headers into the SPI port.

SAMD21 Dev Board assembled

Finish it off by adding a PTH Barrel Jack and a set of standoffs and ¼" 4-40 screws.