Diff: SHT21_ncleee.h

Revision:

0:91e3e396bc6e

Child:

1:73fc5aef174e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SHT21_ncleee.h	Thu Nov 29 10:36:10 2012 +0000
@@ -0,0 +1,104 @@
+/**
+ * SHT21 - Temperature and Humidity Sensor by Sensiron
+ *
+ *  This is a driver to connect to the sensor using an mbed device through an I2C interface
+ *
+ * Author: Graeme Coapes - Newcastle University
+ * Email: graeme.coapes@ncl.ac.uk
+ *
+ * Date:   28/11/2012
+ * 
+ */
+
+#include "mbed.h"
+
+
+#ifndef SHT21_ncleee
+#define SHT21_ncleee
+
+    /*
+     * Constants used in communication
+     *
+     * Refer to datasheet for full explanation
+     */ 
+     
+    //Sensor I2C address
+    #define SHT_I2C_ADDR        0x80
+    
+    //Commands...
+    //Trigger Temp with hold master
+    #define SHT_TRIG_TEMP_HOLD  0xE3
+    //Trigger RH with hold master
+    #define SHT_TRIG_RH_HOLD    0xE5
+    //Trigger Temp with no hold master
+    #define SHT_TRIG_TEMP       0xF3
+    //Trigger RH with no hold master
+    #define SHT_TRIG_RH         0xF5
+    //Write to user register
+    #define SHT_WRITE_REG       0xE6
+    //Read from user register
+    #define SHT_READ_REG        0xE7
+    //Soft reset the sensor
+    #define SHT_SOFT_RESET      0xFE
+    
+    //User Register information
+    
+    //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
+
+    //Battery status
+    #define SHT_BATTERY_STAT    0x40
+    //Enable on chip heater
+    #define SHT_HEATER          0x04
+    //Disable OTP reload
+    #define SHT_DISABLE_OTP     0x02
+    
+    
+    //Fail conditions on the I2C bus
+    #define SHT_FAIL            1
+    #define SHT_SUCCESS         0
+    
+    //Author fail conditions
+    //1, 2, 3 can be used because these are status bits
+    //in the received measurement value
+    #define SHT_GOOD            0xFFFC
+    #define SHT_TRIG_FAIL       1
+    #define SHT_READ_FAIL       2
+    
+    
+    class SHT21
+    {
+        private:
+            I2C *_i2c;
+            int triggerTemp();  
+            int requestTemp();
+            unsigned short temperature;
+            int triggerRH();
+            int requestRH();
+            unsigned short humidity;
+            int wr(int cmd);
+            
+        public:
+        
+            /** Constructor - create a connection to a SHT21 temperature and humidity sensor
+             * through an I2C interface
+             *
+             * @param *i2c a pointer to the i2c interface that is used for communication
+             */             
+            SHT21(I2C *i2c);
+            int readTemp();
+            int readHumidity();
+            int reset();
+            int setPrecision(char precision);
+    
+    };
+    
+    
+#endif