AM2321.h

00001 /**
00002  *  AM2321 (Aosong Guangzhou Electronics)
00003  *  Temperature and Humidity Sensor mbed library
00004  *  Last update : 2014/05/06
00005  */
00006 
00007 #ifndef __AM2321_H__
00008 #define __AM2321_H__
00009 
00010 /** AM2321 (Aosong Guangzhou Electronics)
00011  * Temperature and Humidity Sensor mbed library
00012  * 
00013  * Example:
00014  * @code
00015  * #include "mbed.h"
00016  * #include "AM2321.h"
00017  *
00018  * Serial pc(USBTX, USBRX);    // Tx, Rx
00019  * AM2321 am2321(p28, p27);    // SDA, SCL
00020  *
00021  * int main()
00022  * {
00023  *     while(1)
00024  *     {
00025  *        if(am2321.poll())
00026  *         {
00027  *             pc.printf(":%05u,%.1f,%.1f\n"
00028  *                 , count++
00029  *                 , am2321.getTemperature()
00030  *                 , am2321.getHumidity()
00031  *             );
00032  *         }
00033  * 
00034  *         wait(0.5);
00035  *     }
00036  * }
00037  * @endcode
00038  */
00039 class AM2321
00040 {
00041 private:
00042     typedef struct tagRESULT
00043     {
00044         float temperature;
00045         float humidity;
00046     }RESULT;
00047 
00048 public:
00049     /** Constructor
00050      * @param   sda  [in]    I2C Pin name (SDA)
00051      * @param   scl  [in]    I2C Pin name (SCL)
00052      */
00053     AM2321(PinName sda, PinName scl);
00054     
00055     /** Read current temperature and humidity from AM2321
00056      * @return  result (true=success)
00057      */
00058     bool poll();
00059 
00060     /** Get last read temperature value
00061      * @return  temperature value (degress)
00062      */
00063     float getTemperature(void) const;
00064     
00065     /** Get last read humidity value
00066      * @return  humidity value (%RH)
00067      */ 
00068     float getHumidity(void) const;
00069 
00070 private:
00071     float getLogicalValue(uint16_t regVal) const;
00072     uint16_t calcCRC16(const uint8_t* src, int len) const;
00073 
00074     I2C    _i2c;
00075     RESULT _result;
00076 };
00077 
00078 
00079 #endif // __AM2321_H__