DHT11 with LCD on Arduino Uno

I hacked this DHT11 together today to show the outside temp/humidity. I normally test output to the Serial port but this time I did LCD and serial.  The clear case is a case from Maker Shed. Eventually all this will fit inside the box but until I’m satisfied I’m gonna let it hang…

Below is the code. I added the Dew Point in F.


// include the library code:
#include <LiquidCrystal.h>
#include <dht11.h>

dht11 DHT11;

#define DHT11PIN 6
double DPC;

// initialize the library with the numbers of the interface pins

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

void setup() {
// set up the LCD’s number of columns and rows:
lcd.begin(16, 2);

Serial.println(“DHT11 TEST PROGRAM “);
Serial.print(“LIBRARY VERSION: “);

void loop() {

int chk = DHT11.read(DHT11PIN);

Serial.print(“Read sensor: “);
switch (chk)
case 0: Serial.println(“OK”); break;
case -1: Serial.println(“Checksum error”); break;
case -2: Serial.println(“Time out error”); break;
default: Serial.println(“Unknown error”); break;

Serial.print(“Humidity (%): “);
Serial.println((float)DHT11.humidity, DEC);

Serial.print(“Temperature ( C): “);
Serial.println((float)DHT11.temperature, DEC);

Serial.print(“Temperature ( F): “);
Serial.println(DHT11.fahrenheit(), DEC);

lcd.setCursor(0, 0);
lcd.print(DHT11.humidity, DEC);
lcd.print(” F:”);

lcd.setCursor(0, 1);
DPC= DHT11.dewPoint();

Serial.print(“Dew Point ( F): “);
Serial.println((DPC * 1.8) + 32);
lcd.print(“DP(F): “);
//lcd.print((1.8 * (DHT11.dewPoint(), DEC) + 32));
lcd.print((DPC * 1.8) + 32);

Serial.print(“Dew Point ( C): “);
Serial.println(DHT11.dewPoint(), DEC);

Serial.print(“Dew PointFast ( C): “);
Serial.println(DHT11.dewPointFast(), DEC);



void printDouble( double val, unsigned int precision){
// prints val with number of decimal places determine by precision
// NOTE: precision is 1 followed by the number of zeros for the desired number of decimial places
// example: printDouble( 3.1415, 100); // prints 3.14 (two decimal places)

Serial.print (int(val)); //prints the int part
Serial.print(“.”); // print the decimal point
unsigned int frac;
if(val >= 0)
frac = (val – int(val)) * precision;
frac = (int(val)- val ) * precision;

Serial.println(frac,DEC) ;
lcd.print(frac,DEC) ;

Author: Helicopter Jeff

I'm a vinyl decal cutting and designing, Astrophotography and general photography capturing, RC helicopter/quad copter pilot, Arduino and Raspberry Pi hardware/software developer, network, scripting and troubleshooting ninja living in the metro NY area. I am passionate about my hobbies so much I do them for a living. There's nothing better than getting paid to do what you love.

One thought on “DHT11 with LCD on Arduino Uno”

  1. I’m using PaleMoon (i.e. Firefox) and your sketch includes some HTML lines etc.

    Otherwise looks good, now if I can just get it working….

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