Question

9. Consider a light sensor that is in a "Smart Car". The light sensor is used for turning the headlights on when light sensor does not detect any light. When there is no light on the sensor, the output of the LDR is 15 and when it detects a light, the output is 200. Consider the LDR output is read into à variable "sensorValue". Write a conditional statement that the lights turn on when it is dark. You can use the following command to tum the lights on and off TurnLightsONO: TurnLightsOFFO: I 10. When a car is moving and an obstacle is present on the road, the car may comes to a stop. What sensor is used to detect an obstacle and explain why? Consider the value of the sensor is read into a variable "sensorValue". Write the conditional statement to stop the car if the obstacle is near (you get to decide how close the object should get before car stops). Consider the following command to stop the car (all the car wheels stops spinning): StopTheCarO

Answer 1

Ans 9)

const int lightPin = 13;

const int ldrPin = A0;

void setup() {

Serial.begin(9600);

pinMode(lightPin, OUTPUT);

pinMode(ldrPin, INPUT);

}

void loop() {

int sensorValue = analogRead(ldrPin);

if (sensorValue <= 200) {

digitalWrite(lightPin, HIGH);

Serial.print("Turn lights ON");

} else {

digitalWrite(lightPin, LOW);

Serial.print("Turn Lights OFF");

}

}

Ans 10) To detect obstacle and stop car, ultrasonic sensor is more suitable as it can work in both day and night conditions. You can also measure distance of obstacle with this sensor and stop the car accordingly. Depending on the preset distance you can disable the motors of the car to stop them completely. The code for using ultrasonic sensor shown below turns on the buzzer when obstacle is within the preset distance:

int trigger_pin = 2;

int echo_pin = 3;

int buzzer_pin = 10; 

int time;

int distance; 
int sensorValue;
void setup ( ) {

        Serial.begin (9600); 

        pinMode (trigger_pin, OUTPUT); 

        pinMode (echo_pin, INPUT);

        pinMode (buzzer_pin, OUTPUT);
}

void loop ( ) {

    digitalWrite (trigger_pin, HIGH);

    delayMicroseconds (10);

    digitalWrite (trigger_pin, LOW);

    time = pulseIn (echo_pin, HIGH);

    sensorValue = (time * 0.034) / 2;
    distance = sensorValue;
  if (distance <= 10) 
        {
        Serial.println ("StopTheCar");

        Serial.print (" Distance= ");              

        Serial.println (distance);        

        digitalWrite (buzzer_pin, HIGH);

        delay (500);
        }
  else {

        Serial.println (" Safe to drive ");

        Serial.print (" Distance= ");              

        Serial.println (distance);        

        digitalWrite (buzzer_pin, LOW);

        delay (500);        
  } 
}

Note. You can disable the car motors to stop it by inserting the code same as above code for controlling buzzer, because car circuit details are not given. Also go through the use of ultrasonic sensor and it's pin configurations.

12) You can use following command to set 9600 baud rate.

void setup ( ) {
        Serial.begin (9600); 

}