SparkFun SAMD21 Development Board

RedBoard Turbo - SparkFun Electronics

If you’re ready to step up your Arduino game from older 8-bit/16MHz microcontrollers, the SparkFun RedBoard Turbo is a formidable alternative. At its heart, the RedBoard Turbo uses the ATSAMD21G18, which is an ARM Cortex M0+, 32-bit microcontroller that can run at up to 48MHz. With an impressive 4MB of external flash memory and a UF2 (USB Flashing Format) bootloader, the RedBoard Turbo provides you with an economical and easy to use development platform if you're needing more power than the classic RedBoard.