Since the ATSAML21 is such a close relative to the ATSAMD21, this layout is based somewhat on Adafruit's Feather M0 line. However, it also incorporates solar cells for energy harvesting, an accelerometer, and a barometer. Initial specifications are as follows:

• ATSAML21J18B microcontroller (Cortex M0+, 48MHz max, 256kB flash, 32kB RAM)
• MCP1810 3.3V ultra-low quiescent current voltage regulator
• 2x KXOB25-01X8F monocrystalline solar cells (4.46V, 5.5mA at max power point)
• SWD debug through 10-pin Cortex debugger
• USB micro
• LIS3DH ultra-low power accelerometer
• BMP280 ultra-low power barometer