Temperature Measurement Using MCP9803 and Particle Photon

MCP9803 is a high precision 2-wire temperature sensor. They are equipped with user-programmable registers which facilitate temperature sensing applications. This sensor is suitable for a very sophisticated multi-zone temperature monitoring system.

This lesson shows the interaction of the MCP9803 sensor module with particle photon. To read temperature values, we use particle photon with an I2c adapter. This I2C adapter makes a connection to the sensor module easier and more reliable.

Step 1: Hardware Required:


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

1. MCP9803

2. Particle Photon

3. I2C Cable

4. I2C Shield for particle photon

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 MCP9803 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:

Let’s 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:

// Distributed with a free-will license.
// Use it any way you want, profit or free, provided it fits in the licenses of its associated works.
// MCP9803
// This code is designed to work with the MCP9803_I2CS I2C Mini Module available from ControlEverything.com.
// https://www.controleverything.com/content/Temperature?sku=MCP9803_I2CS#tabs-0-product_tabset-2


// MCP9803 I2C address is 0x48(72)
#define Addr 0x48

float cTemp = 0, fTemp = 0;
void setup()
    // Set variable
    Particle.variable("i2cdevice", "MCP9803");
    Particle.variable("cTemp", cTemp);
    // Initialise I2C communication as MASTER
    // Initialise Serial Communication, set baud rate = 9600
    // Start I2C Transmission
    // Select configuration register
    // Continuous conversion mode, Power-up default
    // Stop I2C Transmission

void loop()
    unsigned int data[2];
    // Starts I2C communication
    // Select data register
    // Stop I2C transmission
    // 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 12-bits
    int temp = ((data[0] * 256) + data[1]) / 16.0;
    if(temp > 2047)
        temp -= 4096;
    cTemp = temp * 0.0625;
    fTemp = cTemp * 1.8 + 32;
    // Output data to serial monitor
    Particle.publish("Temperature in Celsius : ", String(cTemp));
    Particle.publish("Temperature in Fahrenheit : ", String(fTemp));

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:

MCP9803 can be employed in a wide arena of devices which include personal computer and peripherals, hard disk drives, various entertainment systems, office systems, and data communication systems. This sensor can be incorporated in various sophisticated systems.

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