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pinMode()

Sets a GPIO pin's mode — whether the program will use it for digital output or PWM output. Call this in setup(), once per pin, before using the pin.

Signature

void pinMode(int pin, int mode);

Parameters

Parameter Type Description
pin int The pin number (use a named constant from Pins & constants)
mode int One of OUTPUT or PWM_OUTPUT

Return value

None (void).

Modes

Mode Use when…
OUTPUT You will write HIGH or LOW to the pin with digitalWrite()
PWM_OUTPUT You will write a value from 0 to 1024 with pwmWrite()

Example

Setting up two LEDs — one for on/off, one for variable brightness:

void setup(void) {
    pinMode(18, OUTPUT);      // LED on pin 18: digital on/off
    pinMode(12, PWM_OUTPUT);  // LED on pin 12: variable brightness via PWM
}

Note: these pin numbers are arbitrary examples for illustration. The pins you use in the labs are defined as named constants in your .c file — always use those names, not bare numbers.

See also