SHT.h

00001 /* mbed module to use a Sensirion SHT1x /SHT7x sensor
00002  * Copyright (c) 2007-2009 Stephen McGarry
00003  * Released under the MIT License: http://mbed.org/license/mit
00004  */
00005 #ifndef SHT_H
00006 #define SHT_H
00007 
00008 #include "mbed.h"
00009 
00010 
00011 enum SHT_acc {
00012     SHT_low=0,
00013     SHT_high=1
00014 };
00015 
00016 typedef unsigned char byte;
00017 
00018 class SHT {
00019 public:
00020     /* Constructor: SHT
00021      *  Creates an SHT interface connected to specific pins.
00022      *
00023      */
00024     SHT(PinName p_sclk, PinName p_data, SHT_acc p_accuracy);
00025 
00026     /* Functions
00027      */
00028     float get_temperature();     // get the most recent temp reading
00029     float get_humidity();        // get the most recent humidity reading
00030     float get_dewpoint();        // get the most recent dewpoint value
00031     int update(SHT_acc accuracy); // update stored values from sensor
00032 
00033 protected:
00034     byte read_byte(bool send_ack);
00035     char write_byte(byte value);
00036     void trans_start(void);
00037     void connection_reset(void);
00038     char soft_reset();
00039     char read_status(byte &value);
00040     char write_status(byte value);
00041     char measure(int &value, byte mode);
00042     void calculate();
00043 
00044     DigitalOut sclk;
00045     DigitalInOut data;
00046     SHT_acc accuracy;    // will we use high or low accuracy mode on the sensor
00047 
00048     float temperature;    // calculated from sensor reading
00049     float humidity;
00050     float dewpoint;
00051     int temp,hum;        // integer values from sensor before conversion
00052 
00053     enum commands {
00054         com_read_status_reg=0x06,
00055         com_write_status_reg=0x07,
00056         com_measure_temp=0x03,
00057         com_measure_humid=0x05,
00058         com_reset=0x1E
00059     };
00060 
00061     enum acks {
00062         no_ack=0,
00063         send_ack=1
00064     };
00065 };
00066 
00067 #endif