Voltage reference and ATMega328

If I connect an AtMega328 with the Arduino bootloader on it up to a 4.5v voltage source, am I going to have issues reading the analog pins? Do I need to connect a pin to Vcc for an external voltage reference, or will it use the 4.5v input as the reference for those?

If I connect an AtMega328 with the Arduino bootloader on it up to a 4.5v voltage source, am I going to have issues reading the analog pins? Do I need to connect a pin to Vcc for an external voltage reference, or will it use the 4.5v input as the reference for those?

The default analog reference for the Arduino analog input pins is to utilize the Vcc voltage as the reference, so in your case a count reading of 0-1023 for a analog read will be 0-4.5 VDC.

Lefty

Okay, thanks. :slight_smile: