Using IF statement with 2 LEDs

Projects Programming
2

Haveyoueverheartoflayout?Indentation?

pres ctrl+T and see how that looks :slight_smile:

Next, how did you connect those LEDs? I see nothing wrong (at least not with that) in the code.

After some rework:

#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
const byte BlueLedPin = 8;
const byte RedLedPin = 9;
const byte SensorPin = A0;


void setup(){
  lcd.begin(16, 2);
  pinMode(BlueLedPin, OUTPUT);
  //digitalWrite(Blue, LOW); //the default
  pinMode(RedLedPin, OUTPUT);
  //digitalWrite(Red, LOW); //the default

  //pinMode(sensorPin, INPUT); //only applies to the digital mode
  Serial.begin(9600);
}
void loop(){
  unsigned int reading = analogRead(sensorPin);
  float temperatureC = (5.0 * reading * 100.0) / 1024;
  Serial.print(temperatureC);
  
  if (temperatureC >= 20) {
    digitalWrite(RedLedPin, HIGH);
    digitalWrite(BlueLedPin, LOW);
  }
  else{
    digitalWrite(BlueLedPin, HIGH);
    digitalWrite(RedLedPin, LOW);
  }
  
  lcd.setCursor(0, 0);
  lcd.print("TEMP: ");
  lcd.print(temperatureC);
  lcd.print(" C");
  delay(500);
}

Also note, a float does NOT simply mean a decimal point and is pretty hard for a Uno to do.