The ATSAMD21E15B-AU is a microcontroller manufactured by Microchip. It is part of the ATSAMD21 family of microcontrollers, offering an array of peripherals, along with the ARM Cortex M0+ Core. This microcontroller is low power and has 16Kbytes of flash, 2Kbytes of RAM, and multiple serial interfaces. It runs from a 32MHz internal clock and features a 12-bit analog-to-digital converter, two programmable Timers, two Serial Peripheral Interface (SPI) modules, a Universal Serial Bus (USB) controller, and a Watchdog Timer. Additionally, it is capable of running at very low power, with sleep current of only 220nA. It also comes in a small 4 mm × 4 mm TQFP 48 package, providing a space-saving solution for applications. The ATSAMD21E15B-AU is an ideal choice for a variety of applications, including home automation, wearables, and even medical devices.