A microprocessor is a digital device. It only deals with digital inputs and digital outputs. Any voltage lower than about 0.8 volts is considered low. Any voltage above approximately 2.4 volts is considered high. The microprocessor can only read the 0s and 1s. It can also only output 0s and 1s. All analog or continuous input signals or information must be digitized for use by a microprocessor.