The Arduino interface board, just like most other computers, is a digital system that operates on binary values: 1 and 0, on and off, true and false. What if we wanted to know not just whether it was hot or cold outside but rather how hot or cold it was? Or instead of turning an LED on or off, maybe we want to dim or even fade an LED? To do this we need to either convert an analog reading into something that the Arduino can understand or, vice versa, approximate an analog output using digital signals. Where a digital signal has two possible states, an analog signal has many. Because we are dealing with electrical signals, digital states on the Arduino are usually considered to be 0v for LOW or off and +5v for HIGH or on. Analog signals on the other hand might represent any voltage between 0 and +5 volts, infinitely more than just on and off.
KeywordsDuty Cycle Analog Signal Pulse Width Modulation Analog Input Analog Output
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