Question

How should you define the Arduino pin connected to the ECHO pin on the HC-SR04 ultrasonic sensor? a) pinMode(ECHO_PIN, INPUT);

b) pinMode(ECHO_PIN, OUTPUT);
c) pinMode(ECHO_PIN, INPUT_PULLUP);
d) pinMode(ECHO_PIN, INPUT_PULLDOWN);

Answer 1

The Arduino pin connected to the ECHO pin of the HC-SR04 should be defined as an input with pinMode(ECHO_PIN, INPUT); because it receives the echo signal from the sensor.

Step-by-step explanation:

When connecting an HC-SR04 ultrasonic sensor to an Arduino, the pin connected to the ECHO pin of the sensor should be defined as an input. This is because the ECHO pin will send a signal back to the Arduino after detecting an object. Therefore, the correct way to define the ECHO pin in the Arduino code would be:

pinMode(ECHO_PIN, INPUT);

Using INPUT_PULLUP or INPUT_PULLDOWN is not necessary for this kind of sensor as it directly provides a digital signal that does not require the Arduino's internal pull-up or pull-down resistors. Defining it as OUTPUT would be incorrect since the ECHO pin is not used to send data from the Arduino to the sensor but rather to receive the echo signal from the sensor.