MMA7455.h

00001 
00002 #ifndef MMA7455_H
00003 #define MMA7455_H
00004 
00005 
00006 /**
00007  * Freescale Accelerometer MMA7455.
00008  */
00009 class MMA7455 {
00010 public:
00011 
00012     enum Mode {
00013         ModeStandby = 0,
00014         ModeMeasurement = 1,
00015     };
00016 
00017     /** Acceleration range */
00018     enum Range {
00019         Range_8g = 0,
00020         Range_2g = 1,
00021         Range_4g = 2
00022     };
00023 
00024     /**
00025      * Create an interface to the MMA7455 accelerometer
00026      *
00027      * @param sda I2C data line pin
00028      * @param scl I2C clock line pin
00029      */
00030     MMA7455(PinName sda, PinName scl);
00031 
00032     bool setMode(Mode mode);
00033     bool setRange(Range range);
00034 
00035     bool read(int32_t& x, int32_t& y, int32_t& z);
00036 
00037     /**
00038      * Calibrate for 0g, that is, calculate offset to achieve
00039      * 0g values when accelerometer is placed on flat surface.
00040      *
00041      * Please make sure the accelerometer is placed on a flat surface before
00042      * calling this function.
00043      *
00044      * @return true if request was successful; otherwise false
00045      */
00046     bool calibrate();
00047 
00048     /**
00049      * Get calculated offset values. Offsets will be calculated by the
00050      * calibrate() method.
00051      *
00052      * Use these values and put them in persistent storage to avoid
00053      * having to calibrate the accelerometer after a reset/power cycle.
00054      *
00055      * @param xOff x offset is written to this argument
00056      * @param yOff y offset is written to this argument
00057      * @param zOff z offset is written to this argument
00058      *
00059      * @return true if request was successful; otherwise false
00060      */
00061     bool getCalibrationOffsets(int32_t& xOff, int32_t& yOff, int32_t& zOff);
00062 
00063     /**
00064      * Set calibration offset values. These values should normally
00065      * at one point in time have been retrieved by calling the
00066      * getCalibrationOffsets method.
00067      *
00068      *
00069      * @param xOff x offset
00070      * @param yOff y offset
00071      * @param zOff z offset
00072      *
00073      * @return true if request was successful; otherwise false
00074      */
00075     bool setCalibrationOffsets(int32_t xOff, int32_t yOff, int32_t zOff);
00076 
00077 
00078 
00079 private:
00080 
00081     I2C _i2c;
00082     Mode _mode;
00083     Range _range;
00084     int32_t _xOff;
00085     int32_t _yOff;
00086     int32_t _zOff;
00087 
00088     int getStatus();
00089     int getModeControl();
00090     int setModeControl(uint8_t mctl);
00091 
00092 };
00093 
00094 #endif