Stoplight Code Review

In an Arduino sketch, which function runs once to set pin modes before the main cycle begins?

• digitalWrite() starts the program

• changeliights() handles timing

• loop() executes logic repeatedly

• setup() initializes I/O once

Fill in the blank: The Arduino function used to set a digital pin as OUTPUT is (a)   .

Which statement best describes what digitalWrite(pin, HIGH) does in an LED traffic light circuit?

• Introduces a delay before the LED blinks

• Sets the pin LOW to turn the LED off

• Reads the pin level to check the LED

• Sets the pin HIGH to turn the LED on

Given int red=13; int yellow=12; int green=11; which code correctly turns only the yellow LED on for three seconds, then turns it off?

• delay(3000); digitalWrite(yellow, LOW); digitalWrite(yellow, HIGH);

• digitalWrite(yellow, LOW); delay(3000); digitalWrite(yellow, HIGH);

• digitalWrite(yellow, HIGH); delay(3000); digitalWrite(yellow, LOW);

• digitalWrite(yellow, HIGH); digitalWrite(yellow, LOW); delay(3000);

In the provided stoplight sequence, what is the correct order of LEDs turning on, each for 3 seconds?

• Yellow then red then green

• Green then yellow then red

• Red then yellow then green

• Red then green then yellow

A student places delay(1000) between LED state changes in loop(). What does 1000 represent in this context?

• One thousand ticks equals ten seconds

• One thousand cycles equals one minute

• One thousand microseconds equals one second

• One thousand milliseconds equals one second

You need to modify the function changelights() so that each light stays on for 2 seconds instead of 3. Which minimal change achieves this across the sequence?

• Replace each delay(3000) with delay(2000)

• Change digitalWrite to analogWrite

• Add delay(2000) before setup()

• Set pinMode pins to INPUT mode

A bug causes both red and green LEDs to be ON at the same time during the 'yellow on' phase. Which addition directly before yellow HIGH most likely fixes it?

• delay(3000);

• digitalWrite(red, LOW); digitalWrite(green, LOW);

• pinMode(yellow, INPUT);

• digitalWrite(yellow, LOW);

Which Arduino function is responsible for repeatedly executing the main logic of a traffic light sequence?

• setup()

• loop()

• digitalWrite()

• delay()

If you want the green LED to turn off immediately after it turns on, which code line should be added right after digitalWrite(green, HIGH)?

• digitalWrite(red, HIGH);

• delay(3000);

• digitalWrite(yellow, HIGH);

• digitalWrite(green, LOW);