Instead he looks at using the 1.1V internal reference. He’s written some short example code that let’s you measure the incoming line voltage based on that internal reference.

Little Bird Electronics posted an article about using an analog voltage reference with Arduino. This is a tool available when using an analog-to-digital converter. By setting up either an internal … ...

Organizations can use it to collect and visualize sensory data from their Arduino-powered systems. The platform also lends itself to certain other tasks, such as updating devices’ firmware.