LM35 Temperature Sensor ( KEYES KY-070 ) for Arduino

by Sergo Don 7:19 PM 0 comments Arduino KEYES KY-070 LM35 Temperature sensor

Description

Temperature is one of the most commonly measured parameter in the world. They are used in your daily household devices from Microwave,fridges, AC to all fields of engineering. Temperature sensor basically measures the heat/cold generated by an object to which it is connected. It then provides a proportional resistance, current or voltage output which is then measured or processed as per our application.

Temperature sensor are basically classified into two types

• Non Contact Temperature Sensors: These temperature sensors use convection & radiation to monitor temperature 
• Contact Temperature Sensors: Contact temperature sensors arethen further sub divided into three type:

1.  Electro-Mechanical(Thermocouples). 
2.  Resistive Resistance Temperature Detectors (RTD). 
3. Semiconductor based. (LM35, DS1820 etc).
   
    Features of LM35 Temperature Sensor 

• Calibrated directly in Degree Celsius (Centigrade) 
• Linear at 10.0 mV/°C scale factor 
• 0.5°C accuracy guarantee-able (at a25°C) 
• Rated for full -55°C to a 150°C range 
• Suitable for remote applications 
• Low cost due to wafer-level trimming 
• Operates from 4 to 30 volts 
• Less than 60 mA current drain 
• Low self-heating, 0.08°C instill air 
• Non-linearity only 0.25°C typical 
• Low impedance output, 0.1Ωfor 1 mA load
  
  LM35 is a very low cost and easily available Sensor. Main advantage of LM35 is that it is linear i.e. 10mv/°C which means for every degree rise in temperature the output of LM35 will rise by 10mv. So if the output of LM35 is 220mv/0.22V the temperature will be 22°C. So if room temperature is 32°C then the output of LM35 will be 320mv i.e. 0.32V.

Components Needed to Build the LM35 Temperature Sensor Circuit

• Arduino Board 
• LM35 Temperature Sensor IC 
• Computer 
• USB with type A and B connectors

Code

int val;
int tempPin = 1;

void setup()
{
Serial.begin(9600);
}
void loop()
{
val = analogRead(tempPin);
float mv = ( val/1024.0)*5000; 
float cel = mv/10;

Serial.print("TEMPRATURE = ");
Serial.print(cel);
Serial.print("*C value from sensor:");
Serial.print(val);
Serial.println();
delay(1000);
}

Sources :

• http://www.dnatechindia.com/LM35-Temperature-Sensor-Basics.html 
• htttp://playground.arduino.cc/Main/LM35HigherResolution
• http://www.learningaboutelectronics.com/Articles/LM35-temperature-sensor-circuit.php
• http://www.ti.com/lit/ds/symlink/lm35.pdf