Particle Photon - MCP9805 Temperature Sensor Tutorial

MCP9805 is a memory module digital temperature sensor. It is incorporated with user programmable registers that provide flexibility for temperature sensing applications. This sensor is designed to be incorporated in mobile platform memory module temperature sensor. Here is its demonstration with Particle Photon.

1. Particle Photon

2. MCP9805

3. I²C Cable

4. I²C Shield for Particle Photon

Take an I2C shield for particle photon and gently push it over the pins of particle photon.

Then connect the one end of I2C cable to MCP9805 sensor and the other end to the I2C shield.

Connections are shown in the picture above.

The particle code for MCP9805 can be downloaded from our GitHub repository-Dcube Store

Here is the link for the same :

https://github.com/DcubeTechVentures/MCP9805

We have used two libraries for particle code, which are application.h and spark_wiring_i2c.h. Spark_wiring_i2c library is required to facilitate the I2C communication with the sensor.

You can also copy the code from here, it is given as follows:

// 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.

// MCP9805

// This code is designed to work with the MCP9805_I2CS I2C Mini Module available in Dcube Store.

#include

#include

// MCP9805 I2C address is 0x18(24)

#define Addr 0x18

float cTemp = 0, fTemp = 0;

void setup()

{

// Set variable

Particle.variable("i2cdevice", "MCP9805");

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 conversion mode, Power-up default

Wire.write(0x00);

Wire.write(0x00); /

/ Stop I2C Transmission

Wire.endTransmission();

// Start I2C Transmission

Wire.beginTransmission(Addr);

// Select resolution register

Wire.write(0x08);

// Resolution = +0.0625 / C

Wire.write(0x03);

// Stop I2C Transmission

Wire.endTransmission();

}

void loop()

{

unsigned int data[2];

// Starts I2C communication

Wire.beginTransmission(Addr);

// Select data register

Wire.write(0x05);

// 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 13-bits

int temp = ((data[0] & 0x1F) * 256 + data[1]);

if(temp > 4095)

{

temp -= 8192;

}

cTemp = temp * 0.0625;

fTemp = cTemp * 1.8 + 32;

// Output data to dashboard

Particle.publish("Temperature in Celsius : ", String(cTemp));

Particle.publish("Temperature in Fahrenheit : ", String(fTemp));

delay(1000);

}

MCP9805 can be incorporated in various systems which include dual in-line memory module (DIMM) temperature monitoring systems, personal computers and servers. Commonly, it can be used as a general purpose temperature sensor.