Which Arduino function is used to configure a pin's mode (for example INPUT or OUTPUT)?

• A. digitalRead
• B. analogWrite
• C. pinMode
• D. digitalWrite

Answer: (C)

Configuring how a pin behaves is done with a pinMode call. It sets the pin’s role, telling the microcontroller whether the pin will act as an input or an output (and optionally enabling the internal pull-up with INPUT_PULLUP). This setup step is essential before you read from a pin or drive a signal on it. For example, you use pinMode to prepare a pin as OUTPUT before turning an LED on or off with digitalWrite. You would use a pin as INPUT before you read its state with digitalRead.

The other functions perform actions after the pin’s mode is set: digitalRead reads the current digital value on a pin, analogWrite sends a PWM signal on pins that support it, and digitalWrite writes HIGH or LOW to an output pin (and can influence pull-ups in some configurations, but it does not establish the pin’s mode). So configuring the pin’s mode is exactly what pinMode does.