The Sub-µA Current Sensor is a Kinetis K22F-based current measurement board running on FreeRTOS, for use with the FRDM Development Ecosystem or any other Arduino-like development boards. This Reference Design allows for nonintrusive interfacing between any MCU and 3.3V shield, and measurement of a large range of low currents (~60 nA – 5 mA). Multiple communication methods are available, including integration with FRDM Sensor Toolbox (CE).