AK8975.h

00001 /* Library for AK8975 digital compass IC, for use with I2C 
00002 
00003 This library contains basic functionality, if you want more, make it ;) 
00004          
00005 */
00006 
00007 #ifndef AK8975_H
00008 #define AK8975_H
00009 
00010 /**
00011  * Includes
00012  */
00013 #include "mbed.h"
00014 
00015 /**
00016  * Registers
00017  */
00018 #define AK8975_ID_REG       0x00
00019 #define AK8975_ST1_REG      0x02
00020 #define AK8975_X_REG        0x03
00021 #define AK8975_Y_REG        0x05
00022 #define AK8975_Z_REG        0x07
00023 #define AK8975_ST2_REG      0x09
00024 #define AK8975_CONTROL_REG  0x0A
00025 #define AK8975_SELFTEST_REG 0x0C
00026 
00027 /**
00028  * Bits
00029  */
00030 #define AK8975_DRDY_BIT     0
00031 #define AK8975_DERROR_BIT   2
00032 #define AK8975_OFLOW_BIT    3
00033 
00034 #define AK8975_SINGLE_MEASUREMENT 1
00035 
00036 #define AK8975_SENSITIVITY  0.3
00037 
00038 /** AK8975 magnetometer/digital compass simple library.
00039   *
00040   * Example:
00041   * @code
00042   * #include "mbed.h"
00043   * #include "AK8975.h"
00044   * 
00045   * DigitalOut led1(LED1);
00046   * Serial pc(USBTX, USBRX); // tx, rx
00047   * AK8975 mag(p9,p10,0x0E);
00048   * 
00049   * 
00050   * int main() {
00051   *     int data[3];
00052   *     if (mag.testConnection())
00053   *         pc.printf("Connection succeeded. \n");
00054   *     else
00055   *         pc.printf("Connection failed. \n");
00056   *     
00057   *      while(1) {
00058   *         led1=!led1;
00059   *         mag.startMeasurement();
00060   *         wait(0.5);                      //(or use the isReady() function)
00061   *         mag.getAll(data);
00062   *         pc.printf("X: %d", data[0]);
00063   *         pc.putc('\n');
00064   *         pc.printf("Y: %d", data[1]);
00065   *         pc.putc('\n');
00066   *         pc.printf("Z: %d", data[2]);
00067   *         pc.putc('\n');
00068   *     }
00069   * }
00070   * @endcode
00071   */
00072 class AK8975 {
00073     public:
00074      /**
00075      * Constructor.
00076      *
00077      * @param sda - mbed pin to use for the SDA I2C line.
00078      * @param scl - mbed pin to use for the SCL I2C line.
00079      * @param I2Caddress - the I2C address of the device (0x0C - 0x0F)
00080      */
00081      AK8975(PinName sda, PinName scl, char address);
00082      
00083      /**
00084      * Checks connection with the device.
00085      *
00086      * @return - true if working connection, otherwise false
00087      */
00088      bool testConnection( void );
00089      
00090      /**
00091      * Checks if measurement is ready
00092      *
00093      * @return - true if available measurement, otherwise false
00094      */
00095      bool isReady( void );
00096      
00097      /**
00098      * Gets the X data
00099      *
00100      * @return - signed integer containing the raw data
00101      */
00102      int getX( void );
00103      
00104      /**
00105      * Gets the Y data
00106      *
00107      * @return - signed integer containing the raw data
00108      */
00109      int getY( void );
00110      
00111      /**
00112      * Gets the Z data
00113      *
00114      * @return - signed integer containing the raw data
00115      */
00116      int getZ( void );
00117      
00118      /**
00119      * Gets all the data, this is more efficient than calling the functions individually
00120      *
00121      * @param data - pointer to integer array with length 3 where data is stored (data[0]=X - data[1]=Y - data[2]=Z)
00122      */
00123      void getAll( int *data );
00124      
00125         
00126      
00127      /**
00128      * Checks if there is a data error due to reading at wrong moment
00129      *
00130      * @return - true for error, false for no error
00131      */
00132      bool getDataError( void );
00133      
00134      /**
00135      * Checks if a magnetic overflow happened (sensor saturation)
00136      *
00137      * @return - true for error, false for no error
00138      */
00139      bool getOverflow( void );
00140      
00141      /**
00142      * Starts a measurement cycle
00143      */
00144      void startMeasurement( void );
00145      
00146      
00147      
00148      private:
00149      I2C connection;
00150      char deviceAddress;
00151         
00152      /**
00153      * Writes data to the device
00154      *
00155      * @param adress - register address to write to
00156      * @param data - data to write
00157      */
00158      void write( char address, char data);
00159      
00160      /**
00161      * Read data from the device 
00162      *
00163      * @param adress - register address to write to
00164      * @return - data from the register specified by RA
00165      */
00166      char read( char adress);
00167      
00168      /**
00169      * Read multtiple regigsters from the device, more efficient than using multiple normal reads. 
00170      *
00171      * @param adress - register address to write to
00172      * @param length - number of bytes to read
00173      * @param data - pointer where the data needs to be written to 
00174      */
00175      void read( char adress, char *data, int length);
00176 };      
00177 #endif