I got an error says that "state has not been declared please help me for my school project

Projects Programming
1

// Define pins for ultrasonic sensors
const int trigPin1 = 9;
const int echoPin1 = 10;
const int trigPin2 = 11;
const int echoPin2 = 12;

// Define pins for traffic light 1 (Lane 1)
const int redLight1 = 2;
const int yellowLight1 = 3;
const int greenLight1 = 4;

// Define pins for traffic light 2 (Lane 2)
const int redLight2 = 5;
const int yellowLight2 = 6;
const int greenLight2 = 7;

// Define variables for distance
long duration1, distance1;
long duration2, distance2;

// Define threshold distance for object detection (in cm)
const int thresholdDistance = 30;

// Define states for traffic lights
enum TrafficLightState { RED, YELLOW, GREEN };

TrafficLightState state1 = RED;
TrafficLightState state2 = RED;

unsigned long previousMillis = 0;
const long interval = 5000; // 5 seconds interval for each green light

bool lane1Detected = false;
bool lane2Detected = false;

void setup() {
// Initialize serial communication
Serial.begin(9600);

// Set pin modes for ultrasonic sensors
pinMode(trigPin1, OUTPUT);
pinMode(echoPin1, INPUT);
pinMode(trigPin2, OUTPUT);
pinMode(echoPin2, INPUT);

// Set pin modes for traffic lights
pinMode(redLight1, OUTPUT);
pinMode(yellowLight1, OUTPUT);
pinMode(greenLight1, OUTPUT);
pinMode(redLight2, OUTPUT);
pinMode(yellowLight2, OUTPUT);
pinMode(greenLight2, OUTPUT);

// Initialize traffic lights to red
digitalWrite(redLight1, HIGH);
digitalWrite(redLight2, HIGH);
}

void loop() {
// Measure distance from sensor 1
distance1 = measureDistance(trigPin1, echoPin1);
Serial.print("Distance 1: ");
Serial.print(distance1);
Serial.print(" cm, ");

// Measure distance from sensor 2
distance2 = measureDistance(trigPin2, echoPin2);
Serial.print("Distance 2: ");
Serial.print(distance2);
Serial.println(" cm");

// Check for object detection
if (distance1 < thresholdDistance) {
lane1Detected = true;
}
if (distance2 < thresholdDistance) {
lane2Detected = true;
}

// Traffic light logic
if (lane1Detected && !lane2Detected) {
if (state1 != GREEN) {
setTrafficLight(1, GREEN);
setTrafficLight(2, RED);
previousMillis = millis();
state1 = GREEN;
state2 = RED;
}
} else if (lane2Detected && !lane1Detected) {
if (state2 != GREEN) {
setTrafficLight(2, GREEN);
setTrafficLight(1, RED);
previousMillis = millis();
state2 = GREEN;
state1 = RED;
}
}else if(lane1Detected && lane2Detected){
if(state1 != GREEN && state2 != RED){
setTrafficLight(1, GREEN);
setTrafficLight(2, RED);
previousMillis = millis();
state1 = GREEN;
state2 = RED;
}
}

// Automatic traffic light switching after a delay
if (state1 == GREEN && millis() - previousMillis >= interval) {
setTrafficLight(1, YELLOW);
delay(2000);
setTrafficLight(1, RED);
setTrafficLight(2, GREEN);
state1 = RED;
state2 = GREEN;
previousMillis = millis();
} else if (state2 == GREEN && millis() - previousMillis >= interval){
setTrafficLight(2, YELLOW);
delay(2000);
setTrafficLight(2, RED);
setTrafficLight(1, GREEN);
state2 = RED;
state1 = GREEN;
previousMillis = millis();
}

// Reset detection flags after switching
if (state1 == GREEN || state2 == GREEN) {
lane1Detected = false;
lane2Detected = false;
}

delay(100); // Small delay to avoid rapid readings
}

// Function to measure distance using ultrasonic sensor
long measureDistance(int trigPin, int echoPin) {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration1 = pulseIn(echoPin, HIGH);
return duration1 * 0.034 / 2;
}

// Function to set traffic light state
void setTrafficLight(int lightNumber, TrafficLightState state) {
int redPin, yellowPin, greenPin;

if (lightNumber == 1) {
redPin = redLight1;
yellowPin = yellowLight1;
greenPin = greenLight1;
} else {
redPin = redLight2;
yellowPin = yellowLight2;
greenPin = greenLight2;
}

digitalWrite(redPin, LOW);
digitalWrite(yellowPin, LOW);
digitalWrite(greenPin, LOW);

switch (state) {
case RED:
digitalWrite(redPin, HIGH);
break;
case YELLOW:
digitalWrite(yellowPin, HIGH);
break;
case GREEN:
digitalWrite(greenPin, HIGH);
break;
}
}

2

i don't get any errors when i compile the posted code

// Define pins for ultrasonic sensors
const int trigPin1 = 9;
const int echoPin1 = 10;
const int trigPin2 = 11;
const int echoPin2 = 12;

// Define pins for traffic light 1 (Lane 1)
const int redLight1 = 2;
const int yellowLight1 = 3;
const int greenLight1 = 4;

// Define pins for traffic light 2 (Lane 2)
const int redLight2 = 5;
const int yellowLight2 = 6;
const int greenLight2 = 7;

// Define variables for distance
long duration1, distance1;
long duration2, distance2;

// Define threshold distance for object detection (in cm)
const int thresholdDistance = 30;

// Define states for traffic lights
enum TrafficLightState { RED, YELLOW, GREEN };

TrafficLightState state1 = RED;
TrafficLightState state2 = RED;

unsigned long previousMillis = 0;
const long interval = 5000; // 5 seconds interval for each green light

bool lane1Detected = false;
bool lane2Detected = false;

void setup() {
    // Initialize serial communication
    Serial.begin(9600);

    // Set pin modes for ultrasonic sensors
    pinMode(trigPin1, OUTPUT);
    pinMode(echoPin1, INPUT);
    pinMode(trigPin2, OUTPUT);
    pinMode(echoPin2, INPUT);

    // Set pin modes for traffic lights
    pinMode(redLight1, OUTPUT);
    pinMode(yellowLight1, OUTPUT);
    pinMode(greenLight1, OUTPUT);
    pinMode(redLight2, OUTPUT);
    pinMode(yellowLight2, OUTPUT);
    pinMode(greenLight2, OUTPUT);

    // Initialize traffic lights to red
    digitalWrite(redLight1, HIGH);
    digitalWrite(redLight2, HIGH);
}


void loop() {
    // Measure distance from sensor 1
    distance1 = measureDistance(trigPin1, echoPin1);
    Serial.print("Distance 1: ");
    Serial.print(distance1);
    Serial.print(" cm, ");

    // Measure distance from sensor 2
    distance2 = measureDistance(trigPin2, echoPin2);
    Serial.print("Distance 2: ");
    Serial.print(distance2);
    Serial.println(" cm");

    // Check for object detection
    if (distance1 < thresholdDistance) {
        lane1Detected = true;
    }
    if (distance2 < thresholdDistance) {
        lane2Detected = true;
    }

    // Traffic light logic
    if (lane1Detected && !lane2Detected) {
        if (state1 != GREEN) {
            setTrafficLight(1, GREEN);
            setTrafficLight(2, RED);
            previousMillis = millis();
            state1 = GREEN;
            state2 = RED;
        }
    } else if (lane2Detected && !lane1Detected) {
        if (state2 != GREEN) {
            setTrafficLight(2, GREEN);
            setTrafficLight(1, RED);
            previousMillis = millis();
            state2 = GREEN;
            state1 = RED;
        }
    }else if(lane1Detected && lane2Detected){
        if(state1 != GREEN && state2 != RED){
            setTrafficLight(1, GREEN);
            setTrafficLight(2, RED);
            previousMillis = millis();
            state1 = GREEN;
            state2 = RED;
        }
    }

    // Automatic traffic light switching after a delay
    if (state1 == GREEN && millis() - previousMillis >= interval) {
        setTrafficLight(1, YELLOW);
        delay(2000);
        setTrafficLight(1, RED);
        setTrafficLight(2, GREEN);
        state1 = RED;
        state2 = GREEN;
        previousMillis = millis();
    } else if (state2 == GREEN && millis() - previousMillis >= interval){
        setTrafficLight(2, YELLOW);
        delay(2000);
        setTrafficLight(2, RED);
        setTrafficLight(1, GREEN);
        state2 = RED;
        state1 = GREEN;
        previousMillis = millis();
    }

    // Reset detection flags after switching
    if (state1 == GREEN || state2 == GREEN) {
        lane1Detected = false;
        lane2Detected = false;
    }

    delay(100); // Small delay to avoid rapid readings
}


// Function to measure distance using ultrasonic sensor
long measureDistance(int trigPin, int echoPin) {
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    duration1 = pulseIn(echoPin, HIGH);
    return duration1 * 0.034 / 2;
}


// Function to set traffic light state
void setTrafficLight (
    int lightNumber,
    TrafficLightState state)
{
    int redPin, yellowPin, greenPin;

    if (lightNumber == 1) {
        redPin = redLight1;
        yellowPin = yellowLight1;
        greenPin = greenLight1;
    } else {
        redPin = redLight2;
        yellowPin = yellowLight2;
        greenPin = greenLight2;
    }

    digitalWrite(redPin, LOW);
    digitalWrite(yellowPin, LOW);
    digitalWrite(greenPin, LOW);

    switch (state) {
    case RED:
        digitalWrite(redPin, HIGH);
        break;
    case YELLOW:
        digitalWrite(yellowPin, HIGH);
        break;
    case GREEN:
        digitalWrite(greenPin, HIGH);
        break;
    }
}
3

@kets13

Please edit your post, select all code and click the <CODE/> button. Next save your post.

This will apply code tags which makes the code easier to read and copy and the forum software will display it correctly.

1 Like
4

What course is this for and what is the deadline? If you can get a copy of the Arduino Cookbook and skim it cover to cover, you will find some stuff that will help.

1 Like
5

I'm a bit blind, but I see "state1" and "state2", but no "state"

6

Pleas post the full error message. Also in code tags. It will tell on which line of your code the error was found... ...and more...

7

And I am looking through a tiny window.

There is a state, a parameter for this function:

void setTrafficLight(int lightNumber, TrafficLightState state) {

And as @gcjr finds, it compiles fine.

a7

1 Like
8

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