Graeme Coapes / SHT21_ncleee

a library that provides a connection to a SHT21 temperature and humidity sensor Author: Graeme Coapes - Newcastle University, graeme.coapes@ncl.ac.uk Date: 29/11/12

Dependents:   test_ncleee WeatherStation Temp_hum PROJ ... more

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SHT21 Class Reference
Public Member Functions

SHT21 Class Reference

SHT21 Connection class, utilizing a I2C interface. More...

#include <SHT21_ncleee.h>

Public Member Functions

 SHT21 (I2C *i2c)
 Constructor - create a connection to a SHT21 temperature and humidity sensor through an I2C interface.
float readTemp ()
 Read the temperature value from the sensor
.
float readHumidity ()
 Read the humidity value from the sensor
.
int reset ()
 Perform a soft-reset of the sensor unit.
int setPrecision (char precision)
 Set the precision of the measuring.

Detailed Description

SHT21 Connection class, utilizing a I2C interface.

Example: 

   #include "mbed.h"
   #include "SHT21_ncleee.h"
   
   
   DigitalOut myled(LED1);
   Serial pc(USBTX, USBRX);
   I2C i2c(p28,p27);
   SHT21 sht(&i2c);
   
   int main() 
   {
   
       pc.printf("Hello World...\n\tTesting temperature Sensor\n");
       
       int temperature = sht.readTemp();
   
       pc.printf("Temperature is: %d \n", temperature);
       
       pc.printf("Experiment complete...\n");
   
   }

Definition at line 112 of file SHT21_ncleee.h.

Constructor & Destructor Documentation

SHT21 ( I2C *  i2c )

Constructor - create a connection to a SHT21 temperature and humidity sensor through an I2C interface.

Parameters:
*i2ca pointer to the i2c interface that is used for communication

Definition at line 31 of file SHT21_ncleee.cpp.

Member Function Documentation

float readHumidity (  )

Read the humidity value from the sensor
.

Involves triggering the measuring unit then waiting for 100ms for the measuring to complete before reading the humidity

Parameters:
returnsthe percentage humidity

Definition at line 127 of file SHT21_ncleee.cpp.

float readTemp (  )

Read the temperature value from the sensor
.

Involves triggering the measuring unit then waiting for 100ms for the measuring to complete before reading the temperature

Parameters:
returnsa value representing the temperature in degrees centigrade

Definition at line 69 of file SHT21_ncleee.cpp.

int reset (  )

Perform a soft-reset of the sensor unit.

Definition at line 159 of file SHT21_ncleee.cpp.

int setPrecision ( char  precision )

Set the precision of the measuring.

//Data precision settings
//RH 12 T 14 - default
define SHT_PREC_1214 0x00
//RH 8 T 10
define SHT_PREC_0812 0x01
//RH 10 T 13
define SHT_PREC_1013 0x80
//RH 11 T 11
define SHT_PREC_1111 0x81

Parameters:
precision- the precision, refer to above or datasheet.

Definition at line 165 of file SHT21_ncleee.cpp.

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