View source for Experiment 2: Analog Sensor Interfacing (Temperature Sensor -LM35)

== Experiment 2: Analog Sensor Interfacing (Temperature Sensor - LM35) ==

=== Objective ===
To interface the LM35 analog temperature sensor with Arduino and display the output on Serial Monitor or LCD.

=== Task ===
# Connect LM35 to Arduino analog pin.
# Write code to read and convert analog voltage to Celsius.
# Display output on Serial Monitor or LCD.

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⚠️ Disconnect your Arduino from the computer while making or removing component connections.
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=== Circuit Diagram ===
[[File:Eecit-kit-02-circuit.png|center|thumb|400px|Circuit Diagram]]

=== Board Connections ===
[[File:Eecit-kit-02-board-connection.png|center|thumb|400px|Board Connections]]


=== Connections ===
{| class="wikitable" style="text-align:center;"
! LM35 Pin !! Arduino Pin
|-
| VCC (Pin 1) || 5V
|-
| OUT (Pin 2) || A1
|-
| GND (Pin 3) || GND
|}

=== Arduino UNO I2C Pins (for LCD) ===
{| class="wikitable" style="text-align:center;"
! Function !! Arduino UNO Pin
|-
| SDA || A4
|-
| SCL || A5
|}

=== Important ===
Before uploading your Arduino code, make sure you have installed the following libraries in the Arduino IDE:
1. Wire.h – For I²C communication between Arduino and peripheral devices.
2. LiquidCrystal_I2C.h – For controlling LCD displays using the I²C interface.


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✅ Install via (ZIP Method):
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Sketch → Include Library → Add .ZIP Library → Select Downloaded .zip File → Open → Wait for “Library Installed” message
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✅ Verify : 
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Sketch → Include Library → The included library name should be present
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=== Arduino Code ===
<pre>
// © 2025, Cognifront. Member of The IoT Kits Family.

// Experiment 2: Analog Sensor Interfacing (Temperature Sensor -LM35)

// Define the analog input pin for LM35 temperature sensor
const int lm35_pin = A1;  

// Include required libraries for I2C communication and LCD
#include <Wire.h>                
#include <LiquidCrystal_I2C.h>    

// Initialize LCD at I2C address 0x27 with 16 columns and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);  

// Note: Arduino UNO connections for I2C:
// SDA -> A4
// SCL -> A5

void setup() {
  Serial.begin(9600);    // Start serial communication for debugging (9600 baud rate)
  lcd.init();            // Initialize the LCD
  lcd.backlight();       // Turn on the LCD backlight
}

void loop() {
  int temp_adc_val;      // Variable to store raw ADC reading from LM35
  float temp_val;        // Variable to store calculated temperature value in °C

  // Read analog value from LM35 temperature sensor
  temp_adc_val = analogRead(lm35_pin);

  // Convert ADC value (0–1023) to millivolts:
  // Each ADC step = 5V/1024 ≈ 4.88 mV
  temp_val = (temp_adc_val * 4.88);   // Convert to mV

  // LM35 provides 10mV per °C → convert mV to °C
  temp_val = (temp_val / 10);        

  // Print temperature value to Serial Monitor
  Serial.print("Temperature = ");
  Serial.print(temp_val);
  Serial.println(" *C");

  // Clear previous content on LCD before printing new data
  lcd.clear();

  // Display temperature on first line of LCD
  lcd.setCursor(0, 0);               // Set cursor to column 0, row 0
  lcd.print("Temp: ");               // Print label
  lcd.print(temp_val, 1);            // Print temperature with 1 decimal place
  lcd.print((char)223);              // Print degree (°) symbol
  lcd.print("C");                    // Print "C" for Celsius

  // Display sensor name on second line of LCD
  lcd.setCursor(0, 1);               
  lcd.print("LM35 Sensor");          

  // Wait 2 seconds before next reading
  delay(2000);                       
}
</pre>

=== Notes ===
* The LM35 outputs 10mV per °C directly proportional to temperature.  
* Make sure the LCD's I2C address (0x27 in this case) matches your module.  
* For Arduino Uno, I2C pins are SDA → A4 and SCL → A5.

=== Observation ===
* The Serial Monitor displays the real-time temperature in Celsius.  
* The LCD continuously updates and shows the measured temperature along with the label "LM35 Sensor".  
* The temperature reading changes when the sensor is touched or exposed to a different heat source.  

=== Conclusion ===
* The LM35 sensor was successfully interfaced with Arduino.  
* The analog voltage output of the sensor was converted into a temperature value (°C).  
* Data was accurately displayed on both the Serial Monitor and LCD, confirming correct sensor operation and code functionality.

=== Real Life Examples ===
Thermal Monitoring in CNC Machines: The LM35 sensor measures spindle or bearing temperatures to prevent overheating and ensure safe operation of high-speed cutting tools and mechanical components.