The Arduino IDE uses #defines to define things like I/O pin numbers, modes, and other things. You can also create your own headers and #defines. Headers can be included in other files - in other ...

An Arduino sketch usually has five parts: a header describing the sketch and its author; a section defining variables; a setup routine that sets the initial conditions of variables and runs ...

Even though the Arduino board cannot output variable voltage on its digital pins there is a way to generate a rectangular signal that walks periodically between 0V and 5V. int i = 0; const int LED = ...