Which statement best describes the purpose of the pinMode function?

• A. To set a pin's digital output value
• B. To configure a pin as INPUT or OUTPUT
• C. To initialize the serial port
• D. To read an analog value

Answer: (B)

pinMode sets a pin’s mode, telling the microcontroller whether that pin will be used as a digital input or a digital output (and optionally enabling a pull-up). This configuration is essential before you try to read from a pin or drive it high or low. For example, you’d configure a LED pin as OUTPUT and then use digitalWrite to turn it on or off. If you’re reading a button, you’d configure the button pin as INPUT and then use digitalRead to check its state. Some environments also let you enable an internal pull-up with INPUT_PULLUP, which helps when wiring a button to avoid floating values. Other activities, like writing a value to a pin, reading an analog value, or starting serial communication, use different functions (digitalWrite, analogRead, Serial.begin), not pinMode.