Component:

1. Raspberry pi
2. LCD 16*2
3. DHT Sensor
4. Jumper wires
5. Bread board

Installing the Adafruit LCD library on Raspberry Pi:

The value of the temperature and humidity will be displayed on a 16*2 LCD display. Adafruit provides us a library to easily operate this LCD in 4-bit mode, so let us add it to our Raspberry Pi by opening the terminal window Pi and following the below steps.

Step 1: Install git on your Raspberry Pi by using the below line. Git allows you to clone any project files on Github and use it on your Raspberry pi. Our library is on Github so we have to install git to download that library into pi.

apt-get install git

Step 2: The following line links to the GitHub page where the library is present just execute the line to clone the project file on Pi home directory

git clone git://github.com/adafruit/Adafruit_Python_CharLCD

Step 3: Use the below command to change directory line, to get into the project file that we just downloaded. The command line is given below

cd Adafruit_Python_CharLCD

Step 4: Inside the directory there will be a file called setup.py, we have to install it, to install the library. Use the following code to install the library

sudo python setup.py install

That is it the library should have been installed successfully. Now similarly let’s proceed with installing the DHT library which is also from Adafruit.

Code:

#Program to read the values of Temp and Humidity from the DHT11 sensor and display them on the LCD

#Website: www.iotianhub.com

import time #import time for creating delay 
import Adafruit_CharLCD as LCD #Import LCD library 
import Adafruit_DHT #Import DHT Library for sensor

sensor_name = Adafruit_DHT.DHT11 #we are using the DHT11 sensor
sensor_pin = 17 #The sensor is connected to GPIO17 on Pi

lcd_rs        = 7  #RS of LCD is connected to GPIO 7 on PI
lcd_en        = 8  #EN of LCD is connected to GPIO 8 on PI 
lcd_d4        = 25 #D4 of LCD is connected to GPIO 25 on PI
lcd_d5        = 24 #D5 of LCD is connected to GPIO 24 on PI
lcd_d6        = 23 #D6 of LCD is connected to GPIO 23 on PI
lcd_d7        = 18 #D7 of LCD is connected to GPIO 18 on PI
lcd_backlight =  0  #LED is not connected so we assign to 0

lcd_columns = 16 #for 16*2 LCD
lcd_rows    = 2 #for 16*2 LCD

lcd = LCD.Adafruit_CharLCD(lcd_rs, lcd_en, lcd_d4, lcd_d5, lcd_d6, lcd_d7, 
lcd_columns, lcd_rows, lcd_backlight)   #Send all the pin details to library

lcd.message('DHT11 with Pi \n -CircuitDigest') #Give a intro message

time.sleep(2) #wait for 2 secs

while 1: #Infinite Loop
humidity, temperature = Adafruit_DHT.read_retry(sensor_name, sensor_pin) #read from sensor and save respective values in temperature and humidity varibale  
lcd.clear() #Clear the LCD screen
 lcd.message ('Temp = %.1f C' % temperature) # Display the value of temperature
  lcd.message ('\nHum = %.1f %%' % humidity)  #Display the value of Humidity

time.sleep(2) #Wait for 2 sec then update the values