Digital Input Voltage Over Time

Shaded segments are HIGH (button pressed); flat segments at 0 V are LOW (released).

What This Shows

There is no in-between. The line is at 0 V or 5 V and the transition is vertical -- that is what makes the signal digital.

Compare this shape to the smooth curve an analog input produces. A digital pin answers one question, high or low, and every reading is one of two values. Press the button below to add another event and watch the pattern extend: still only two heights, however many times you press.