# Installing CircuitPython on SAMD21 Boards ## Overview ![](https://cdn-learn.adafruit.com/assets/assets/000/067/625/medium800/microcontrollers_blinka_samd.jpg?1544809505) 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://www.adafruit.com/product/3333), [METRO M0 Express](https://www.adafruit.com/product/3505), and [Feather M0 Express](https://www.adafruit.com/product/3403), 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! ![](https://cdn-learn.adafruit.com/assets/assets/000/067/382/medium800/circuitpython_Micros2.jpg?1544459948) Info: - [Next Page](https://learn.adafruit.com/installing-circuitpython-on-samd21-boards/install-arduino-board-definition.md) ## Featured Products ### Adafruit Feather M0 Basic Proto - ATSAMD21 Cortex M0 [Adafruit Feather M0 Basic Proto - ATSAMD21 Cortex M0](https://www.adafruit.com/product/2772) Feather is the new development board from Adafruit, and like its namesake it is thin, light, and lets you fly! We designed Feather to be a new standard for portable microcontroller cores. This is the  **Feather M0 Basic Proto** , it has a bunch of prototyping space... In Stock [Buy Now](https://www.adafruit.com/product/2772) [Related Guides to the Product](https://learn.adafruit.com/products/2772/guides) ### Circuit Playground Express [Circuit Playground Express](https://www.adafruit.com/product/3333) **Circuit Playground Express** is the next step towards a perfect introduction to electronics and programming. We've taken the original Circuit Playground Classic and made it even better! Not only did we pack even more sensors in, we also made it even easier to... In Stock [Buy Now](https://www.adafruit.com/product/3333) [Related Guides to the Product](https://learn.adafruit.com/products/3333/guides) ### Adafruit METRO M0 Express - designed for CircuitPython [Adafruit METRO M0 Express - designed for CircuitPython](https://www.adafruit.com/product/3505) Metro is our series of microcontroller boards for use with the Arduino IDE. This new **Metro M0 Express** board looks a whole lot like our [original Metro 328](https://www.adafruit.com/product/2488), but with a huge upgrade. Instead of the ATmega328, this Metro... In Stock [Buy Now](https://www.adafruit.com/product/3505) [Related Guides to the Product](https://learn.adafruit.com/products/3505/guides) ### Adafruit Feather M0 Express [Adafruit Feather M0 Express](https://www.adafruit.com/product/3403) At the Feather M0's heart is an ATSAMD21G18 ARM Cortex M0+ processor, clocked at 48 MHz and at 3.3V logic, the same one used in the new [Arduino Zero](https://www.adafruit.com/products/2843). This chip has a whopping 256K of FLASH (8x more than the Atmega328 or 32u4) and... Out of Stock [Buy Now](https://www.adafruit.com/product/3403) [Related Guides to the Product](https://learn.adafruit.com/products/3403/guides) ## Related Guides - [Adafruit Feather M0 Express](https://learn.adafruit.com/adafruit-feather-m0-express-designed-for-circuit-python-circuitpython.md) - [Adafruit Metro M0 Express](https://learn.adafruit.com/adafruit-metro-m0-express.md) - [Adafruit Circuit Playground Express](https://learn.adafruit.com/adafruit-circuit-playground-express.md) - [Glowing Neopixel Resin River Table](https://learn.adafruit.com/glowing-neopixel-resin-river-table.md) - [CircuitPython Hardware: ILI9341 TFT & FeatherWing](https://learn.adafruit.com/micropython-hardware-ili9341-tft-and-featherwing.md) - [Crickit Controlled Animatronic Eyeball](https://learn.adafruit.com/crickit-controlled-animatronic-eyeball.md) - [Pushrod Garage](https://learn.adafruit.com/pushrod-garage.md) - [Circuit Playground Express Laser Tag](https://learn.adafruit.com/circuit-playground-express-laser-tag.md) - [UFO Flying Saucer with Circuit Playground Express](https://learn.adafruit.com/ufo-circuit-playground-express.md) - [Using WebUSB with Arduino and TinyUSB](https://learn.adafruit.com/using-webusb-with-arduino-and-tinyusb.md) - [CircuitPython Hardware: SD Cards](https://learn.adafruit.com/micropython-hardware-sd-cards.md) - [AdaBox 006](https://learn.adafruit.com/adabox006.md) - [CircuitPython Hardware: PCA9685 DC Motor & Stepper Driver](https://learn.adafruit.com/micropython-hardware-pca9685-dc-motor-and-stepper-driver.md) - [Comparison and Experimentation with Flammable Gas Sensors](https://learn.adafruit.com/gas-sensor-comparison.md) - [DAC Hacks for Circuit Playground Express & other ATSAMD21 Boards](https://learn.adafruit.com/circuit-playground-express-dac-hacks.md) - [Which CircuitPython Board is Right for You?](https://learn.adafruit.com/choose-your-circuitpython-board.md) - [Using Piezo Buzzers with CircuitPython & Arduino](https://learn.adafruit.com/using-piezo-buzzers-with-circuitpython-arduino.md) - [ScoutMakes FM Radio Board STEMMA I2C](https://learn.adafruit.com/scoutmakes-fm-radio-board-stemma-i2c.md)