Introduction: Measurement of Temperature Using LM75BIMM and Particle Photon
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 particle photon has been illustrated. To read the temperature values, we have used particle with an I2c adapter.This I2C adapter makes the connection to the sensor module easy and more reliable.
Step 1: Hardware Required:
Step 2: Hardware Hookup:
The hardware hookup section basically explains the wiring connections required between the sensor and the particle photon. 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:
Lets start with the particle code now.
While using the sensor module with the particle, we include application.h and spark_wiring_i2c.h library. "application.h" and spark_wiring_i2c.h library contains the functions which facilitate the i2c communication between the sensor and the particle.
The entire particle code is given below for the convenience of the user:
#include<Application.h>
#include<spark_wiring_i2c.h>
// LM75BIMM I2C address is 0x49(73)
#define Addr 0x49
double cTemp = 0.0, fTemp = 0.0;
void setup()
{
// Set variable
Particle.variable("i2cdevice", "LM75BIMM");
Particle.variable("cTemp", cTemp);
// 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;
}
cTemp = temp * 0.5;
fTemp = cTemp * 1.8 + 32;
// Output data to dashboard
Particle.publish("Temperature in Celsius: ", String(cTemp));
delay(1000);
Particle.publish("Temperature in Fahrenheit: ", String(fTemp));
delay(1000);
}
Particle.variable() function creates the variables to store the output of the sensor and Particle.publish() function displays the output on the dashboard of the site.
The sensor output is shown in the picture above for your reference.
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.