28. Precision voltmeter using ADC

Build a voltmeter using AVR ATmega/ Arduino UNO, which measures voltage from 0 to 5 volts and provides a resolution of

• 1 mV resolution for a 0 to 1.1 volts voltage range.
• 4.88 mV resolution for a 1.1 to 5 volts voltage range.

Hints: Change ADC voltage reference according to input voltage range.

Note: This task is specific to AVR ATmega/ Arduino controllers.