The SparkFun SAMD21 Mini Breakout has been equipped with a USB interface for programming and power, surrounded with an RTC crystal, and a 600mA 3.3V regulator. By utilizing the Pro R3’s extra PCB real-estate we've been able to leave room for a few extra GPIO pins. We’ve pinned the Mini Breakout to match – as much as possible – our faithful Pro Mini and Pro Micro. The I/O and voltage rails are all broken out to a pair of breadboard-compatible headers. Power can be supplied, and the board can be programmed, through the micro-B USB connector.
One of the most unique features of the SAMD21 is SERCOM – a set of six configurable serial interfaces that can be turned into either a UART, I2C master, I2C slave, SPI master, or SPI slave. Each SERCOM provides for a lot of flexibility: the ports can be multiplexed, giving you a choice of which task each pin is assigned.
Note: The breakout does NOT have headers installed and will need to purchased and soldered on yourself.