MAX31855.h

00001 #ifndef MAX31855_H
00002 #define MAX31855_H
00003 
00004 #include "mbed.h"
00005 /** MAX31855 class.
00006  *  Used for read MAX31855 Cold-Junction Compensated Thermocouple-to-Digital Converter
00007  *
00008  * Example:
00009  * @code
00010  * DigitalOut led(LED2);
00011  * Serial pc(USBTX,USBRX);
00012  * MAX31855 therm(p5,p6,p7,p8);
00013  * 
00014  * int main() 
00015  * {
00016  *     while(1) 
00017  *     {
00018  *         pc.printf("T=%f;Chip=%f\r\n",therm.thermocouple(),therm.chip());
00019  *         led  = therm.fault();
00020  *         wait(0.5);
00021  *     }
00022  * }
00023  * @endcode
00024  */  
00025 class MAX31855
00026 {
00027 public:
00028     /** Create MAX31855 instance connected to spi & ncs
00029     * @param mosi SPI master out slave in pin (MAX31855 is only read device)
00030     * @param miso SPI master in slave out pin
00031     * @param sck SPI clock pin
00032     * @param ncs pin to connect at CS input
00033     */
00034     MAX31855(PinName mosi, PinName miso, PinName sck, PinName ncs);
00035     
00036     /** Create MAX31855 instance connected to spi & ncs
00037     * @param SPI bus instance (MAX31855 is only read device)
00038     * @param ncs pin to connect at CS input
00039     */
00040     MAX31855(SPI& spi, PinName ncs);
00041     
00042     /**Get Thermocouple temperature
00043     * @returns temperature [°C]
00044     */    
00045     float thermocouple(void);
00046     
00047     /**Get Chip temperature
00048     * @returns temperature [°C]
00049     */       
00050     float chip(void);
00051     
00052     /**Check if thermocouple disconnected
00053     */
00054     bool opened(void);
00055     
00056     /**Check if an error
00057     */
00058     bool fault(void);
00059     
00060     /**Check if thermocouple short-circuited to Vcc
00061     */
00062     bool scToVcc(void);
00063     
00064     /**Check if thermocouple shorted-circuited to GND
00065     */
00066     bool scToGnd(void);
00067 
00068 #ifdef MBED_OPERATORS
00069     /** An operator shorthand for thermocouple()
00070      *
00071      * The float() operator can be used as a shorthand for thermocouple() to simplify common code sequences
00072      *
00073      * Example:
00074      * @code
00075      * float x = temp.thermocouple();
00076      * float x = temp;
00077      *
00078      * if(temp.thermocouple() > 20.25) { ... }
00079      * if(temp > 20.25) { ... }
00080      * @endcode
00081      */
00082     operator float(){return thermocouple();}
00083 #endif
00084     
00085 protected:
00086     void read(void);
00087       
00088 private:
00089     SPI         _spi;
00090     DigitalOut  _ncs;
00091     float       _t;
00092     float       _chip_t;
00093     bool        _fault;
00094     bool        _scv;
00095     bool        _scg;
00096     bool        _oc;
00097 };
00098 
00099 #endif