Introduction: Measurement of Temperature Using LM75BIMM and Raspberry Pi

About: We are a group of makers. We work in IoT, IOS app, android app, embedded design, sensor design, raspberry pi, arduino, beaglebone, particle electron, particle photon, Bluetooth.

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 raspberry pi is demonstrated and its programming using Java language has also been illustrated. To read the temperature values, we have used raspberry pi with an I2C adapter.This I2C adapter makes the connection to the sensor module easy and more reliable.

Step 1: Hardware Required:

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


2. Raspberry Pi

3. I2C Cable

4. I2C Shield for raspberry pi

5. Ethernet cable

Step 2: Hardware Hookup:

The hardware hookup section basically explains the wiring connections required between the sensor and the raspberry pi. 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.

Step 3: Code for Temperature Measurement:

The advantage of using raspberry pi is, that is provides you the flexibility of the programming language in which you want to program the board in order to interface the sensor with it. Harnessing this advantage of this board, we are demonstrating here its programming in the Java. The java code for LM75BIMM can be downloaded from our github community that is Control Everything Community.

As well as for the ease of the users, we are explaining the code here also:

As the first step of coding you need to download the pi4j library in case of java, because this library supports the functions used in the code. So, to download the library you can visit the following link:

You can copy the working java code for this sensor from here also:

<p>import;</p><p>import;</p><p>import;</p><p>import;</p><p>public class LM75BIMM</p><p>{	</p><p>public static void main(String args[]) throws Exception	</p><p>{		</p><p>// Create I2C bus		</p><p>I2CBus Bus = I2CFactory.getInstance(I2CBus.BUS_1);		</p><p>// Get I2C device, LM75BIMM I2C address is 0x49(73)		</p><p>I2CDevice device = Bus.getDevice(0x49);</p><p>// Select configuration register		</p><p>// Continuous conversion mode, normal operation		</p><p>device.write(0x01, (byte)0x00);		</p><p>Thread.sleep(500);</p><p>// Read 2 bytes of data from address 0x00(0)		</p><p>// temp msb, temp lsb		</p><p>byte[] data = new byte[2];		</p><p>, data, 0, 2);</p><p>// Convert the data to 9-bits		</p><p>int temp = ((data[0] & 0xFF) * 256 + (data[1] & 0x80)) / 128;		</p><p>if(temp > 255)		</p><p>{			</p><p>temp -= 512;		</p><p>}		</p><p>double cTemp = temp * 0.5;		</p><p>double fTemp = cTemp * 1.8 + 32;</p><p>// Output data to screen		</p><p>System.out.printf("Temperature in Celsisus : %.2f C %n", cTemp);		</p><p>System.out.printf("Temperature in Fahrenheit : %.2f F %n", fTemp);	</p><p>}</p><p>}</p>

The library which facilitates i2c communication between the sensor and the board is pi4j, its various packages I2CBus, I2CDevice and I2CFactory help to establish the connection.


write() and read() functions are used to write some particular commands to the sensor to make it work in a particular mode and read the sensor output respectively.

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

Step 4: Applications:

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.