</>(Uno R3) I'm trying to set up a temperature sensor and an LCD screen to display the temp. Can anybody Help?

[mtgchicken]

#include <dht.h>
#include <LiquidCrystal.h>

#define DHT11_PIN 7
#define DHT11_PIN 2 // which?

dht DHT;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup()
{
Serial.begin(9600);
lcd.begin(16, 2);
}

void loop() {
int chk = DHT.read11(DHT11_PIN);
Serial.print("Temperature = ");
Serial.println(DHT.temperature);
Serial.print("Humidity = ");
Serial.println(DHT.humidity);
delay(1000);
lcd.setCursor(0, 0);
lcd.print("Temp: ");
lcd.print(DHT.temperature);
lcd.print((char)223);
lcd.print("C");
lcd.setCursor(0, 1);
lcd.print("Humidity: ");
lcd.print(DHT.humidity);
lcd.print("%");
delay(1000);

}

Eventually I'm gonna put a motor trigger in there too for when the temp. is under a certain degree. This is my first time ever using Arduino.

Edit: Now the code seems to work, but the lit LCD screen is blank

[anon35827816]

@mtgchicken

#include <dht.h>

dht DHT;
void setup() {
#define DHT11_PIN 7
  Serial.begin(9600);
#define DHT11_PIN 2
#include <LiquidCrystal.h>
  LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
  lcd.begin(16, 2);

}

void loop() {
  int chk = DHT.read11(DHT11_PIN);
  Serial.print("Temperature = ");
  Serial.println(DHT.temperature);
  Serial.print("Humidity = ");
  Serial.println(DHT.humidity);
  delay(1000);
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(DHT.temperature);
  lcd.print((char)223);
  lcd.print("C");
  lcd.setCursor(0, 1);
  lcd.print("Humidity: ");
  lcd.print(DHT.humidity);
  lcd.print("%");
  delay(1000);

}

@mtgchicken

This is my first time ever using Arduino.

Don't give up in any case

The compiler already gives useful hints.
Firstly, you're trying to instantiate the lcd object in two different ways, and the first way apparently does not align with the constructor of the library you're using. It looks like you're actually using a library for an I2C display - can you confirm that your display is in fact I2C? With how many wires is it connected to the Arduino?
If you're using lcd.begin(16,2) to start the lcd, you'll need to add a line with this before the setup routine:
LiquidCrystal lcd;

Furthermore, when attempting to read the temperature, I think you're trying to call a function that won't do what you expect it to do. I think you actually want to call readHumidity() and readTemperature() as you can see for instance in this example:

adafruit/DHT-sensor-library/blob/master/examples/DHTtester/DHTtester.ino

In general, especially when you're new, it's a good idea to try and run the examples that come with the libraries you use. If you get those to work, then try and work in the essential parts of the examples into your own sketch.

Also, take one step at a time. So try and get your lcd to work, and in a separate sketch try to get the dht sensor to work (using Serial outputs for debugging). Once they both work, combine them into one sketch.

There may be other bugs in your code that I didn't address, but I'd suggest to start here and see how you fare.

[ruilviana]

hi @mtgchicken .
I've already found 2 errors.
1st. error.
You did not read :

How to get the best out of this forum

See also FAQ - Arduino Forum for general rules on forum behaviour and etiquette. Hello, Welcome to the Arduino Forum. This guide explains how to get the best out of this forum. Please read and follow the instructions below. Being new here you might think this is having rules for the sake of rules, but that is not the case. If you don’t follow the guidelines all that happens is there is a long exchange of posts while we try to get you to tell us what we need in order to help you, which is fru…

2nd error.
You did not use </> tags to post your sketch.
RV mineirin

[groundFungus]

@mtgchicken

void setup() {
#define DHT11_PIN 7
Serial.begin(9600);
#define DHT11_PIN 2
#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
lcd.begin(16, 2);

}

The constructor for the LCD is in setup(). That makes it local to setup() and it goes out of scope when setup() completes. Same for the DHT stuff. Move everything except Serial.begin and lcd.begin out of setup().

Like this:

#include <dht.h>
#include <LiquidCrystal.h>

#define DHT11_PIN 7
#define DHT11_PIN 2 // which?

dht DHT;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup()
{
   Serial.begin(9600);
   lcd.begin(16, 2);
}

[mtgchicken]

@anon35827816

Furthermore, when attempting to read the temperature, I think you're trying to call a function that won't do what you expect it to do. I think you actually want to call readHumidity() and readTemperature() as you can see for instance in this example:

I don't see what you are referencing to. Do you mind elaborating?

[anon35827816]

I'd recommend to download the example I linked to and carefully read each line of code in it (it's not long) and try to understand what each line does. It'll clarify itself that way. You will probably recognize the functions I mentioned, which do what you want.