Measurement of Temperature Using LM75BIMM and Arduino Nano

LM75BIMM is a digital temperature sensor incorporated with thermal watchdog and has two wire interface which supports its operation upto 400 kHz. It has an over temperature output with programmable limit and hystersis.

In this tutorial the interfacing of the LM75BIMM sensor module with arduino nano has been illustrated. To read the temperature values, we have used arduino with an I2c adapter.This I2C adapter makes the connection to the sensor module easy and more reliable.

The materials that we need for accomplishing our goal includes the following hardware components:

1. LM75BIMM

2. Arduino Nano

3. I2C Cable

4. I2C Shield for arduino nano

The hardware hookup section basically explains the wiring connections required between the sensor and the arduino nano. Ensuring correct connections is the basic necessity while working on any system for the desired output. So, the requisite connections are as follows:

The LM75BIMM will work over I2C . Here is the example wiring diagram, demonstrating how to wire up each interface of the sensor.

Out-of-the-box, the board is configured for an I2C interface, as such we recommend using this hookup if you’re otherwise agnostic.

All you need is four wires! Only four connections are required Vcc, Gnd, SCL and SDA pins and these are connected with the help of I2C cable.

These connections are demonstrated in the pictures above.

Lets start with the arduino code now.

While using the sensor module with the arduino, we include Wire.h library. "Wire" library contains the functions which facilitate the i2c communication between the sensor and the arduino board.

The entire arduino code is given below for the convenience of the user:

#include<Wire.h>
// LM75BIMM I2C address is 0x49(73)
#define Addr 0x49
void setup() 
{  
// Initialise I2C communication as MASTER  
Wire.begin();  
// Initialise Serial communication, set baud rate = 9600  
Serial.begin(9600);
// Start I2C Transmission  
Wire.beginTransmission(Addr);  
// Select configuration register  
Wire.write(0x01);  
// Continuous operation, normal operation  
Wire.write(0x00);  
// Stop I2C Transmission  
Wire.endTransmission();    
delay(300);
}
void loop()
{   
unsigned int data[2];    
// Start I2C Transmission  
Wire.beginTransmission(Addr);  
// Select temperature data register  
Wire.write(0x00);  
// Stop I2C Transmission  
Wire.endTransmission();    
// Request 2 bytes of data  
Wire.requestFrom(Addr,2);
// Read 2 bytes of data  
// temp msb, temp lsb  
if(Wire.available()==2)  
{    
data[0] = Wire.read();    
data[1] = Wire.read();  
}       
// Convert the data to 9-bits  
int temp = (data[0] * 256 + (data[1] & 0x80)) / 128;  
if (temp > 255)  
{    
temp -= 512;  
}  
float cTemp = temp * 0.5;  
float fTemp = cTemp * 1.8 + 32;    
// Output data to serial monitor  
Serial.print("Temperature in Celsius:  ");  
Serial.print(cTemp);  
Serial.println(" C");  
Serial.print("Temperature in Fahrenheit:  ");  
Serial.print(fTemp);  
Serial.println(" F");    
delay(1000);
}

In wire library Wire.write() and Wire.read() is used to write the commands and read the sensor output.

Serial.print() and Serial.println() is used to display the output of the sensor on the serial monitor of the Arduino IDE.

The output of the sensor is shown in the picture above.

LM75BIMM is ideal for a number of applications including base stations, electronic test equipment, office electronics, personal computers or any other system where temperature monitoring is critical to performance. Therefore, this sensor has a pivotal role in many of the highly temperature sensitive systems.