# Proper Debugging of ATSAMD21 Processors ## Overview ![](https://cdn-learn.adafruit.com/assets/assets/000/030/766/medium800/arduino_debugging.png?1456441379) Chances are if you're programming firmware on a microcontroller you've had to do some 'fun' debugging. Button presses, interrupts, small memory spaces...it can make debugging quite a challenge! A lot of beginners lean on tried-and-true (if a little frustrating) printf statments or toggling GPIO's with LEDs on them. And don't get me wrong, those techniques work pretty well. But if you come from a software background you're probably used to really nice debugging setups, often built into the IDE Of course its a ton easier to debug software when the computer is running both software and development platform. It's a lot tougher when the processor is physically separated, with its own memory, clocks, peripherals, and its not even of the same _processor family!_ No worries though, there's a full industry set up to create programming/debug dongles and adapters! [One of our favorites is SEGGER's J-Link family](https://www.adafruit.com/?q=segger). They're not _cheap_ but they do support a vast number of chips. ![](https://cdn-learn.adafruit.com/assets/assets/000/030/764/medium800/arduino_2209-00.jpg?1456441177) Atmel also has it's own debugger chip, the [EDBG](http://www.atmel.com/webdoc/protocoldocs/ch01s01.html) (apparently its a AT32UC3A4256 programmed with Atmels proprietary firmware) This chip comes on every Arduino Zero and is used to both program and debug firmware ![](https://cdn-learn.adafruit.com/assets/assets/000/030/765/medium800/arduino_2843-04.jpg?1456441242) You may be wondering "OK so how do I actually do said debugging?" Well you've come to the right place because we're gonna show you how. In this guide we'll show how to debug the ATSAMD21 family (specifically the ATSAMD21G18) which is in the [Arduino Zero](https://www.adafruit.com/products/2843) and [Feather M0](https://www.adafruit.com/?q=feather%20m0&) family, by using the EDBG or J-Link. - [Next Page](https://learn.adafruit.com/proper-step-debugging-atsamd21-arduino-zero-m0/install-software.md) ## Featured Products ### SEGGER J-Link EDU - JTAG/SWD Debugger [SEGGER J-Link EDU - JTAG/SWD Debugger](https://www.adafruit.com/product/1369) [Discontinued - **you can grab ** SEGGER J-Link EDU Mini - JTAG/SWD Debugger **instead!**](https://www.adafruit.com/product/3571) The SEGGER J-Link EDU is identical to the more expensive [J-Link BASE](https://www.adafruit.com/products/2209) model except... No Longer Stocked [Buy Now](https://www.adafruit.com/product/1369) [Related Guides to the Product](https://learn.adafruit.com/products/1369/guides) ### SEGGER J-Link BASE - JTAG/SWD Debugger [SEGGER J-Link BASE - JTAG/SWD Debugger](https://www.adafruit.com/product/2209) The SEGGER J-Link BASE is identical to the cheaper [J-Link EDU](https://www.adafruit.com/products/1369) model except for the **terms of use**. If you're going to use your debugger strictly for personal, non-commercial projects, such as publishing... In Stock [Buy Now](https://www.adafruit.com/product/2209) [Related Guides to the Product](https://learn.adafruit.com/products/2209/guides) ### Arduino Zero - 32 bit Cortex M0 Arduino with Debug Interface [Arduino Zero - 32 bit Cortex M0 Arduino with Debug Interface](https://www.adafruit.com/product/2843) With the new **Arduino Zero** , the more creative individual will have the potential to create one’s most imaginative and new ideas for IoT devices, wearable technologies, high tech automation, wild robotics and other not yet thinkable adventures in the world of... No Longer Stocked [Buy Now](https://www.adafruit.com/product/2843) [Related Guides to the Product](https://learn.adafruit.com/products/2843/guides) ### Arduino M0 Pro - 32 bit Cortex M0 with Debug Interface [Arduino M0 Pro - 32 bit Cortex M0 with Debug Interface](https://www.adafruit.com/product/2417) With the new **Arduino M0 Pro** board, the more creative individual will have the potential to create one’s most imaginative and new ideas for IoT devices, wearable technologies, high tech automation, wild robotics and other not yet thinkable adventures in the world of... No Longer Stocked [Buy Now](https://www.adafruit.com/product/2417) [Related Guides to the Product](https://learn.adafruit.com/products/2417/guides) ### 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) ### Adafruit Feather M0 Adalogger [Adafruit Feather M0 Adalogger](https://www.adafruit.com/product/2796) 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  **Adafruit Feather M0 Adalogger**  - our take on an... In Stock [Buy Now](https://www.adafruit.com/product/2796) [Related Guides to the Product](https://learn.adafruit.com/products/2796/guides) ### Adafruit Feather M0 Bluefruit LE [Adafruit Feather M0 Bluefruit LE](https://www.adafruit.com/product/2995) 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  **Adafruit Feather M0 Bluefruit LE**  - our take on an... In Stock [Buy Now](https://www.adafruit.com/product/2995) [Related Guides to the Product](https://learn.adafruit.com/products/2995/guides) ### Adafruit Feather M0 WiFi - ATSAMD21 + ATWINC1500 [Adafruit Feather M0 WiFi - ATSAMD21 + ATWINC1500](https://www.adafruit.com/product/3010) 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  **Adafruit Feather M0 WiFi w/ATWINC1500** - our take on an... In Stock [Buy Now](https://www.adafruit.com/product/3010) [Related Guides to the Product](https://learn.adafruit.com/products/3010/guides) ## Related Guides - [Adafruit Feather M0 Adalogger](https://learn.adafruit.com/adafruit-feather-m0-adalogger.md) - [Adafruit Feather M0 Bluefruit LE](https://learn.adafruit.com/adafruit-feather-m0-bluefruit-le.md) - [DAC Hacks for Circuit Playground Express & other ATSAMD21 Boards](https://learn.adafruit.com/circuit-playground-express-dac-hacks.md) - [CircuitPython Hardware: Charlieplex LED Matrix](https://learn.adafruit.com/micropython-hardware-charlieplex-led-matrix.md) - [Using MPL3115A2 with CircuitPython](https://learn.adafruit.com/using-mpl3115a2-with-circuitpython.md) - [Debug Header for the Feather [M0]](https://learn.adafruit.com/make-a-simple-debugging-featherwing-for-the-m0.md) - [Make it Move with Crickit](https://learn.adafruit.com/make-it-move-with-crickit.md) - [Using ATSAMD21 SERCOM for more SPI, I2C and Serial ports](https://learn.adafruit.com/using-atsamd21-sercom-to-add-more-spi-i2c-serial-ports.md) - [Bluetooth Remote Control for the Lego Droid Developer Kit](https://learn.adafruit.com/bluetooth-remote-for-lego-droid.md) - [MUNNY Glowing Friend with Bluetooth Control!](https://learn.adafruit.com/munny-lamp.md) - [MicroPython Displays: Drawing Text](https://learn.adafruit.com/micropython-displays-drawing-text.md) - [CircuitPython Hardware: PCA9685 PWM & Servo Driver](https://learn.adafruit.com/micropython-hardware-pca9685-pwm-and-servo-driver.md) - [How to Choose a Microcontroller](https://learn.adafruit.com/how-to-choose-a-microcontroller.md) - [Installing CircuitPython on SAMD21 Boards](https://learn.adafruit.com/installing-circuitpython-on-samd21-boards.md) - [Guardian Shield+ Zelda Breath of the Wild](https://learn.adafruit.com/guardian-shield-zelda-breath-of-the-wild.md) - [CircuitPython Hardware: PCA9685 DC Motor & Stepper Driver](https://learn.adafruit.com/micropython-hardware-pca9685-dc-motor-and-stepper-driver.md) - [Internet of Things Infrared Remote](https://learn.adafruit.com/internet-of-things-infrared-remote.md)