This won’t work correctly, though: the microcontroller on the watch is very good at getting the power it needs from anywhere, and connecting it directly to an Arduino would skew the results.

Build Your Own Arduino Voltmeter Circuit and Voltage Divider Which Can Measure Voltages From 0V to 30V, Including 12V. Visit To learn More.

This project is a great example. [Scott Daniels] takes a look at the other voltage measurement options available to AVR chips used by Arduino.

The Mayfly Data logger is a fully programmable microprocessor board which is fully compatible with the Arduino IDE and is equipped with a Atmega 1284p processor supported by 128K flash memory and ...

The extendable Arduino GPS data logger consists of a shield that is fitted with the GPS receiver, SD card reader, and accelerometer, together with an Arduino UNO board. This combination of ...