Electrical – Understanding microcontroller ADC input pins (atmega328)

adcatmegafloatingpullup

If I set up the ADC on the ATmega328 to read from a certain ADC pin, what state is the ADC pin put in to?

Since I don't explicitly enable any pull ups, is the pin floating/high voltage/low voltage?

Best Answer

Since I don't explicitly enable any pull ups, is the pin floating/high voltage/low voltage

The pin state is whatever voltage you are feeding into that pin. If you are feeding in 3V then the pin reads the binary equivalent of 3V. If you feed in 2V then the pin reads the binary equivalent of 2V.

If you don't connect anything to the pin then it is floating.

When working with ADC there is no concept of HIGH or LOW, only discrete quanta of voltages (\$\frac{1}{1024}V_{ref}/LSB\$).