Arduino - LM35 Temperature Sensor
|1||×||Arduino UNO or Genuino UNO|
|1||×||USB 2.0 cable type A/B|
|1||×||LM35 Temperature Sensor|
|1||×||(Optional) 9V Power Adapter for Arduino|
|1||×||(Recommended) Screw Terminal Block Shield for Arduino Uno|
Or you can buy the following sensor kit:
|1||×||DIYables Sensor Kit 30 types, 69 units|
About LM35 Temperature Sensor
LM35 temperature sensor has three pins:
- GND pin: needs to be connected to GND (0V)
- VCC pin: needs to be connected to VCC (5V)
- OUT pin: signal pin gives the output voltage that is linearly proportional to the temperature, should be connected to a analog pin on Arduino.
How It Works
The LM35 outputs the voltage linearly proportional to the Centigrade temperature. The output scale factor of the LM35 is 10 mV/°C. It means that the temperature is calculated by dividing the voltage (mV) in output pin by 10.
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How To Program For LM35 Temperature Sensor
- Get the ADC value from the temperature sensor by using analogRead() function.
- Convert the ADC value to voltage in millivolt
- Convert the voltage to the temperature in Celsius
- (Optional) Convert the Celsius to Fahrenheit
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Grasp the sensor by your hand
- See the result on Serial Monitor.
Improving the Temperature Precision
In the above code, we use ADC reference voltage by default (5V~5000mV). We can increase the temperature resolution by changing reference voltage to INTERNAL (1.1V~1100mV). This reference voltage can be changed using the analogReference() function.
The below table show the diffrent between using 5000mV and 1100mV reference voltage
|Vref(mV)||5000 mV (by default)||1100 mV (INTERNAL)|
|Reading Resolution||5000/1024 = 4.88 mV||1100/1024 = 1.07 mV|
|Temperature Resolution||0.488 °C||0.107 °C|
|Temperature Range||0 to 500 °C||0 to 110 °C|
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