LDR, LEDs and Push button

Projects Programming
1

Hi,
I'm still new to arduino, I want to turn on ledRed when the ldrStatus goes below 900 but I want it to stay on until I press the button when at that point the ledRed will turn off and ledGreen will come on.
With the ledGreen I want that to go be on when ldrStatus is above 900 and ledRed to be off.
What's the best way to do this?
Thanks

const int ldr = A0; //ldr pin A0
const int ledRed = 13; //red Led pin 13
const int ledGreen = 12; //green Led pin 12
const int pushButton = 2; //pushButton in pin 2
int buttonState = 0; //variable for reading pushButton Status

void setup() {
  Serial.begin(9600);
  pinMode(ldr, INPUT);
  pinMode(ledRed, OUTPUT);
  pinMode(ledGreen, OUTPUT);
  pinMode (pushButton, INPUT);
}

void loop() {
  int ldrStatus = analogRead(ldr);
  buttonState = digitalRead(pushButton);
  if (ldrStatus <= 900) {
    digitalWrite(ledRed, HIGH);
    digitalWrite(ledGreen, LOW);
    Serial.print("FAIL");
    Serial.println(ldrStatus);
  }
  else {
    digitalWrite(ledGreen, HIGH);
    digitalWrite(ledRed, LOW);
    Serial.print("VALID");
    Serial.println(ldrStatus);
  }
}
2

You need a boolean to track the "alarm" state as I call it. Here is my take take on it. It compiles but I have not fully tested it. Also, I changed the button to INPUT_PULLUP and assumed the pressed state was LOW. Yours may be wired differently.

const int ldr = A0; //ldr pin A0
const int ledRed = 13; //red Led pin 13
const int ledGreen = 12; //green Led pin 12
const int pushButton = 2; //pushButton in pin 2
int lastButtonState;
bool ldrAlarm = false;
bool lastLdrAlarm = false;

void setup() {
  Serial.begin(9600);
  pinMode(ldr, INPUT);
  pinMode(ledRed, OUTPUT);
  pinMode(ledGreen, OUTPUT);
  pinMode(pushButton, INPUT_PULLUP);
  lastButtonState = digitalRead(pushButton);
  digitalWrite(ledRed, LOW);
  digitalWrite(ledGreen, HIGH);
}

void loop() {
  int ldrStatus = analogRead(ldr);
  int buttonState = digitalRead(pushButton);
  
  if (buttonState != lastButtonState)
  {
    delay(50); // debounce
    lastButtonState = buttonState;
    if (buttonState == LOW)
    {
      ldrAlarm = false;
    }
  }
  
  if (ldrStatus <= 900) {
    ldrAlarm = true;
  }
  else {
    Serial.print("VALID");
    Serial.println(ldrStatus);
  }

  if (ldrAlarm != lastLdrAlarm) {
    lastLdrAlarm = ldrAlarm;
    if (ldrAlarm) {
      digitalWrite(ledRed, HIGH);
      digitalWrite(ledGreen, LOW);
      Serial.print("FAIL ");
      Serial.println(ldrStatus);
    }
    else {
      digitalWrite(ledGreen, HIGH);
      digitalWrite(ledRed, LOW);
    }
  }  
}
3

consider

const int ldr = A0; //ldr pin A0
const int ledRed = 13; //red Led pin 13
const int ledGreen = 12; //green Led pin 12

#if 0       // my hardware
const int pushButton = A1;
#else
const int pushButton = 2; //pushButton in pin 2
#endif

int buttonState = 0; //variable for reading pushButton Status

void setup() {
    Serial.begin(9600);
    pinMode(ldr, INPUT);
    pinMode(ledRed, OUTPUT);
    pinMode(ledGreen, OUTPUT);

    pinMode (pushButton, INPUT_PULLUP);
    buttonState = digitalRead (pushButton);
}

void loop() {
    int ldrStatus = analogRead(ldr);
    int but       = digitalRead(pushButton);

    if (ldrStatus <= 900) {
        digitalWrite(ledRed, HIGH);
        digitalWrite(ledGreen, LOW);

        Serial.print("FAIL ");
        Serial.println(ldrStatus);
    }
    else if (buttonState != but)  {
        buttonState = but;
        if (LOW == but)  {
            digitalWrite(ledGreen, HIGH);
            digitalWrite(ledRed, LOW);
            Serial.print("VALID");
            Serial.println(ldrStatus);
        }
    }
}
4

Thanks both of these worked!
Now to learn boolean logic.
Thanks

5

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