To use it, you pass it the number of the pin to configure and the constant INPUT or OUTPUT. The pinMode ( ) function configures a pin as either an input or an output.
These parameters are used by the pinMode ( ) function to decide which pin and mode to set. For example, the line pinMode ( ledPin, OUTPUT ) calls the pinMode ( ) function, passing it two parameters: ledPin and OUTPUT. You can call a function that's already been defined (either in your sketch or as part of the Arduino language). The code between the is called the body of the function: what the function does. The text before and after the name specify its return type and parameters: these will be explained later. The first line provides information about the function, like its name, "setup".
For example, here's the definition of the setup ( ) function from the Blink example: FunctionsĪ function (otherwise known as a procedure or sub-routine) is a named piece of code that can be used from elsewhere in a sketch. There's more information in the Variables tutorial. For example, you could store the value read from an input into a variable. Often, however, the value of a variable will change while the sketch runs. The advantage of using a variable is that it's easier to move the LED to a different pin: you only need to edit the one line that assigns the initial value to the variable.
In this case, the person writing the program could have chosen not to bother creating the ledPin variable and instead have simply written 13 everywhere they needed to specify a pin number. Every time the name ledPin appears in the code, its value will be retrieved. It's being used to indicate which Arduino pin the LED is connected to. For example, the line from the Blink sketch above declares a variable with the name ledPin, the type int, and an initial value of 13. VariablesĪ variable is a place for storing a piece of data. The message "LED connected to digital pin 13" is a comment.
1 int ledPin = 13 // LED connected to digital pin 13
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