MSP430FR4133 LaunchPad and SHT31 sensor example using Energia

In this article we connect a SHT31 temperature and humidity sensors to a MSP430FR4133 LaunchPad

SHT31 is the next generation of Sensirion’s temperature and humidity sensors. It builds on a new CMOSens® sensor chip that is at the heart of Sensirion’s new humidity and temperature platform.

The SHT3x-DIS has increased intelligence, reliability and improved accuracy specifications compared to its predecessor. Its functionality includes enhanced signal processing, two distinctive and user selectable I2C addresses and communication speeds of up to 1 MHz. The DFN package has a footprint of 2.5 x 2.5 mm2 while keeping a height of 0.9 mm.

This allows for integration of the SHT3x-DIS into a great variety of applications.

Features

Fully calibrated, linearized, and temperature compensated digital output
Wide supply voltage range, from 2.4 V to 5.5 V
I2C Interface with communication speeds up to 1 MHz and two user selectable addresses

Size	2.5 x 2.5 x 0.9 mm
Output	I²C, Voltage Out
Supply voltage range	2.15 to 5.5 V
Energy consumption	4.8µW (at 2.4 V, low repeatability, 1 measurement / s)
RH operating range	0 – 100% RH
T operating range	-40 to +125°C (-40 to +257°F)
RH response time	8 sec (tau63%)

 

I bought the following module

Parts Required

 

Name	Link
MSP430FR4133 LaunchPad	MSP430FR4133 LaunchPad development board MSP-EXP430FR4133
SHT31
Connecting wire	Free shipping Dupont line 120pcs 20cm male to male + male to female and female to female jumper wire

 

Schematic/Connection

Here are the connectors on the launchpad

 

MSP430FR4133 Launchpad	Sensor
3.3v	Vin
Gnd	Gnd
SDA P8_2	SDA
SCL P8_3	SCL

 

Code

[codesyntax lang=”cpp”]

#include <Wire.h>

// SHT31 I2C address is 0x44(68)
#define Addr 0x44

void setup()
{
  // Initialise I2C communication as MASTER
  Wire.begin();
  // Initialise serial communication, set baud rate = 9600
  Serial.begin(9600);
  delay(300);
}

void loop()
{
  unsigned int data[6];

  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Send 16-bit command byte
  Wire.write(0x2C);
  Wire.write(0x06);
  // Stop I2C transmission
  Wire.endTransmission();
  delay(300);

  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Stop I2C Transmission
  Wire.endTransmission();

  // Request 6 bytes of data
  Wire.requestFrom(Addr, 6);

  // Read 6 bytes of data
  // temp msb, temp lsb, temp crc, hum msb, hum lsb, hum crc
  if (Wire.available() == 6)
  {
    data[0] = Wire.read();
    data[1] = Wire.read();
    data[2] = Wire.read();
    data[3] = Wire.read();
    data[4] = Wire.read();
    data[5] = Wire.read();
  }
  // Convert the data
  int temp = (data[0] * 256) + data[1];
  float cTemp = -45.0 + (175.0 * temp / 65535.0);
  float fTemp = (cTemp * 1.8) + 32.0;
  float humidity = (100.0 * ((data[3] * 256.0) + data[4])) / 65535.0;

  // 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");
  Serial.print("Relative Humidity :");
  Serial.print(humidity);
  Serial.println(" %RH");
  delay(500);
}

[/codesyntax]

Output

Open the serial monitor

Temperature in Celsius :22.94 C
Temperature in Fahrenheit :73.30 F
Relative Humidity :42.03 %RH
Temperature in Celsius :22.93 C
Temperature in Fahrenheit :73.27 F
Relative Humidity :42.04 %RH
Temperature in Celsius :22.92 C
Temperature in Fahrenheit :73.25 F
Relative Humidity :42.07 %RH