TEMPERATURE SENSOR ON THE LCD DISPLAY, USING ARDUINO MEGA

You can use an Arduino to monitor the air temperature by using an LM35 temperature sensor

The LM35 is an ideal temperature sensor for measuring ambient temperature. It provides a linear output proportional to the temperature, with 0 V corresponding to 0 degrees C and an output voltage change of 10 mV for each degree C change. LM35s are easier to use than thermistors and thermocouples because they are so linear and require no signal conditioning.

The output of an LM35 can be connected directly to a Arduino analog input. Because the Arduino analog-to-digital converter (ADC) has a resolution of 1024 bits, and the reference voltage is 5 V, the equation used to calculate the temperature from the ADC value is:

temp = ((5.0 * analogRead(TemperaturePin)) / 1024) * 100.0

To display the temperature, we will use a liquid crystal display (LCD).

Experiment

The purpose of this experiment to build a temperature monitor using an LM35, a 16x2 LCD, and an Arduino.

Hardware Required

1 x Arduino Mega2560
1 x LCD
1 x 5 kohm potentiometer
1 x breadboard
1 x LM35 temperature sensor
1 x 1k ohm resistor
Female connectors
jumper wires

Wiring Diagram

circuit diagram of temerature sensor interface with arduino mega

Connect the components as shown in the figure above. A 1 kohm resistr is connected between the LM35 output and GND to limit the current without affecting the output voltage.

The LCD is connected to the Arduino as shown below. The middle terminal of the potentiometer is connected to pin 3 of the LCD to change the brightness of the LCD backlight. The other two pins of the potentiometer are connected to 5 V and GND. Enable is connected to Arduino pin 9 of Arduino and RS is connected to Arduino pin 8. RW is connected to ground.

DB4-----> pin4

DB5----->pin5

DB6----->pin6

DB7----->pin7

RS----->pin8

EN----->pin9

Code

The program uses the LiquidCrystal.h library to write data to the display. In the loop(), the value of the sensor output is continually read, converted to degrees C, then displayed on the LCD.

#include //arduino lcd library LiquidCrystal lcd(8,9,4,5,6,7); //defining lcd pins int value=0; //initializing variables float volts=0.0; float temp=0.0; float tempF=0.0; void setup() { pinMode(3,INPUT); //setting arduino pin3 as input Serial.begin(9600); // opens serial port, sets data rate to 9600 bps lcd.begin(16,2); // set up the LCD's number of columns and rows } void loop() { value=analogRead(A0); //read from A0 volts=(value/1024.0)*5.0; //conversion to volts temp= volts*100.0; //conversion to temp Celsius tempF=temp*9/5+32; //conversion to temp Fahrenheit //display temp no lcd Serial.print("temperature= "); Serial.println(temp); lcd.setCursor(0,0); lcd.print("TEMP= "); lcd.print(temp); lcd.print(" C"); lcd.setCursor(0,1); lcd.print("TEMP= "); lcd.print(tempF); lcd.print(" F"); delay(500); }