MPLAB® Harmony 3 is a software development framework consisting of compatible and interoperable modules that include peripheral libraries (PLIBs), drivers, system services, middleware and third-party libraries. The MPLAB Harmony Configurator (MHC) is a GUI-based tool that provides an easy way to enable and configure various MPLAB Harmony modules. The MHC is a plug-in to the MPLAB X Integrated Development Environment (IDE). You can find more details about MPLAB Harmony v3 at https://www.microchip.com/mplab/mplab-harmony This video introduces SAM D21 Curiosity Nano Evaluation Kit and explains how to create a simple application on Microchip's ARM® Cortex®-M0+ based flash SAM D21 microcontroller using Harmony v3 MHC. The application demonstrates an LED (LED0) toggling periodically and prints the LED toggling rate on a serial terminal. The timeout periodicity will change from 500 milliseconds to one second, two seconds, four seconds and back to 500 milliseconds every time you press the switch SW0 on the SAM D21 Curiosity Nano Evaluation Kit. Reference Links SAM D21 Curiosity Nano Evaluation Kit and getting started demo: https://www.microchip.com/Developmenttools/ProductDetails/DM320119 GitHub Repo: https://github.com/MicrochipTech/MPLAB-Harmony-Reference-Apps GitHub link for SAM D21 Curiosity Nano: https://github.com/MicrochipTech/MPLAB-Harmony-Reference-Apps/tree/master/apps/sam_d21_cnano Demo user guide: https://microchiptech.github.io/MPLAB-Harmony-Reference-Apps/apps/sam_d21_cnano/samd21n_getting_started/readme.html Getting started with SAM D21 MCUs Video - Create Your First Project with SAMD21 Using MPLAB® Harmony v3: https://www.youtube.com/watch?v=S02mAli_DTU&ab_channel=MicrochipTechnology