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Show/hide line numbers <title>MMA8452.h Source File</title>

MMA8452.h

00001 #pragma once
00002 
00003 // Authors: Ashley Mills, Nicholas Herriot
00004 /* Copyright (c) 2013 Vodafone, MIT License
00005  *
00006  * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
00007  * and associated documentation files (the "Software"), to deal in the Software without restriction,
00008  * including without limitation the rights to use, copy, modify, merge, publish, distribute,
00009  * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
00010  * furnished to do so, subject to the following conditions:
00011  *
00012  * The above copyright notice and this permission notice shall be included in all copies or
00013  * substantial portions of the Software.
00014  *
00015  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
00016  * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00017  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
00018  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00020  */
00021 
00022 // the SparkFun breakout board defaults to 1, set to 0 if SA0 jumper on the bottom of the board is set
00023 // see the Table 10. I2C Device Address Sequence in Freescale MMA8452Q pdf
00024  
00025 #include "mbed.h" 
00026 
00027 #define MMA8452_DEBUG 1
00028 
00029 // More info on MCU Master address can be found on section 5.10.1 of http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MMA8452Q
00030 #define SA0 1
00031 #if SA0
00032   #define MMA8452_ADDRESS 0x3A // 0x1D<<1  // SA0 is high, 0x1C if low - 
00033 #else
00034   #define MMA8452_ADDRESS 0x38 // 0x1C<<1
00035 #endif
00036 
00037 // Register descriptions found in section 6 of pdf
00038 #define MMA8452_STATUS 0x00        // Type 'read' : Status of the data registers
00039 #define MMA8452_OUT_X_MSB 0x01     // Type 'read' : x axis - MSB of 2 byte sample
00040 #define MMA8452_OUT_X_LSB 0x02     // Type 'read' : x axis - LSB of 2 byte sample
00041 #define MMA8452_OUT_Y_MSB 0x03     // Type 'read' : y axis - MSB of 2 byte sample
00042 #define MMA8452_OUT_Y_LSB 0x04     // Type 'read' : y axis - LSB of 2 byte sample
00043 #define MMA8452_OUT_Z_MSB 0x05     // Type 'read' : z axis - MSB of 2 byte sample
00044 #define MMA8452_OUT_Z_LSB 0x06     // Type 'read' : z axis - LSB of 2 byte sample
00045 
00046 // register definitions
00047 #define MMA8452_XYZ_DATA_CFG 0x0E
00048 
00049 #define MMA8452_SYSMOD 0x0B        // Type 'read' : This tells you if device is active, sleep or standy 0x00=STANDBY 0x01=WAKE 0x02=SLEEP
00050 #define MMA8452_WHO_AM_I 0x0D      // Type 'read' : This should return the device id of 0x2A
00051 
00052 #define MMA8452_PL_STATUS 0x10     // Type 'read' : This shows portrait landscape mode orientation
00053 #define MMA8452_PL_CFG 0x11        // Type 'read/write' : This allows portrait landscape configuration
00054 #define MMA8452_PL_COUNT 0x12      // Type 'read' : This is the portraint landscape debounce counter
00055 #define MMA8452_PL_BF_ZCOMP 0x13   // Type 'read' :
00056 #define MMA8452_PL_THS_REG 0x14    // Type 'read' :
00057 
00058 #define MMA8452_FF_MT_CFG 0X15     // Type 'read/write' : Freefaul motion functional block configuration
00059 #define MMA8452_FF_MT_SRC 0X16     // Type 'read' : Freefaul motion event source register
00060 #define MMA8452_FF_MT_THS 0X17     // Type 'read' : Freefaul motion threshold register
00061 #define MMA8452_FF_COUNT 0X18      // Type 'read' : Freefaul motion debouce counter
00062 
00063 #define MMA8452_ASLP_COUNT 0x29    // Type 'read/write' : Counter settings for auto sleep
00064 #define MMA8452_CTRL_REG_1 0x2A    // Type 'read/write' :
00065 #define MMA8452_CTRL_REG_2 0x2B    // Type 'read/write' :
00066 #define MMA8452_CTRL_REG_3 0x2C    // Type 'read/write' :
00067 #define MMA8452_CTRL_REG_4 0x2D    // Type 'read/write' :
00068 #define MMA8452_CTRL_REG_5 0x2E    // Type 'read/write' :
00069 
00070 // Defined in table 13 of the Freescale PDF
00071 /// xxx these all need to have better names
00072 #define STANDBY 0x00                        // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
00073 #define WAKE 0x01                           // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
00074 #define SLEEP 0x02                          // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
00075 #define ACTIVE 0x01                         // Stage value returned and set in Control Register 1, it can be STANDBY=00, or ACTIVE=01
00076  
00077 #define TILT_STATUS 0x03        // Tilt Status (Read only)
00078 #define SRST_STATUS 0x04        // Sample Rate Status Register (Read only)
00079 #define SPCNT_STATUS 0x05       // Sleep Count Register (Read/Write)
00080 #define INTSU_STATUS 0x06       // Interrupt Setup Register
00081 #define MODE_STATUS 0x07        // Mode Register (Read/Write)
00082 #define SR_STATUS 0x08          // Auto-Wake and Active Mode Portrait/Landscape Samples per Seconds Register (Read/Write)
00083 #define PDET_STATUS 0x09        // Tap/Pulse Detection Register (Read/Write)
00084 #define PD_STATUS 0xA           // Tap/Pulse Debounce Count Register (Read/Write)
00085  
00086 // masks for enabling/disabling standby
00087 #define MMA8452_ACTIVE_MASK 0x01
00088 #define MMA8452_STANDBY_MASK 0xFE
00089 
00090 // mask for dynamic range reading and writing
00091 #define MMA8452_DYNAMIC_RANGE_MASK 0xFC
00092 
00093 // mask and shift for data rate reading and writing
00094 #define MMA8452_DATA_RATE_MASK 0xC7
00095 #define MMA8452_DATA_RATE_MASK_SHIFT 0x03
00096 
00097 // mask and shift for general reading and writing
00098 #define MMA8452_WRITE_MASK 0xFE
00099 #define MMA8452_READ_MASK 0x01
00100 
00101 // mask and shift for bit depth reading and writing
00102 #define MMA8452_BIT_DEPTH_MASK 0xFD
00103 #define MMA8452_BIT_DEPTH_MASK_SHIFT 0x01
00104 
00105 // status masks and shifts
00106 #define MMA8452_STATUS_ZYXDR_MASK 0x08
00107 #define MMA8452_STATUS_ZDR_MASK 0x04
00108 #define MMA8452_STATUS_YDR_MASK 0x02
00109 #define MMA8452_STATUS_XDR_MASK 0x01
00110 
00111 /**
00112  * Wrapper for the MMA8452 I2C driven accelerometer.
00113  */
00114 class MMA8452 {
00115             
00116     public:
00117     
00118        enum DynamicRange {
00119            DYNAMIC_RANGE_2G=0x00,
00120            DYNAMIC_RANGE_4G,
00121            DYNAMIC_RANGE_8G,
00122            DYNAMIC_RANGE_UNKNOWN
00123        };
00124         
00125        enum BitDepth {
00126            BIT_DEPTH_12=0x00,
00127            BIT_DEPTH_8, // 1 sets fast read mode, hence the inversion
00128            BIT_DEPTH_UNKNOWN
00129        };
00130        
00131        enum DataRateHz {
00132           RATE_800=0x00,
00133           RATE_400,
00134           RATE_200,
00135           RATE_100,
00136           RATE_50,
00137           RATE_12_5,
00138           RATE_6_25,
00139           RATE_1_563,
00140           RATE_UNKNOWN
00141        };
00142          
00143        /**
00144         * Create an accelerometer object connected to the specified I2C pins.
00145         *
00146         * @param sda I2C data port
00147         * @param scl I2C clock port
00148         * @param frequency 
00149         * 
00150         */ 
00151       MMA8452(PinName sda, PinName scl, int frequency);
00152        
00153       /// Destructor
00154       ~MMA8452();
00155       
00156       /**
00157        * Puts the MMA8452 in active mode.
00158        * @return 0 on success, 1 on failure.
00159        */
00160       int activate();
00161  
00162       /**
00163        * Puts the MMA8452 in standby.
00164        * @return 0 on success, 1 on failure.
00165        */
00166       int standby();      
00167     
00168        /**
00169         * Read the device ID from the accelerometer (should be 0x2a)
00170         *
00171         * @param dst pointer to store the ID
00172         * @return 0 on success, 1 on failure.
00173         */        
00174       int getDeviceID(char* dst);  
00175       
00176       /**
00177        * Read the MMA8452 status register.
00178        *
00179        * @param dst pointer to store the register value.
00180        * @ return 0 on success, 1 on failure.
00181        */
00182       int getStatus(char* dst);  
00183       
00184       /** 
00185        * Read the raw x, y, an z registers of the MMA8452 in one operation.
00186        * All three registers are read sequentially and stored in the provided buffer.
00187        * The stored values are signed 2's complement left-aligned 12 or 8 bit integers.
00188        *
00189        * @param dst The destination buffer. Note that this needs to be 3 bytes for
00190        * BIT_DEPTH_8 and 6 bytes for BIT_DEPTH_12. It is upto the caller to ensure this.
00191        * @return 0 for success, and 1 for failure
00192        * @sa setBitDepth
00193        */ 
00194       int readXYZRaw(char *dst);
00195       
00196       /// Read the raw x register into the provided buffer. @sa readXYZRaw
00197       int readXRaw(char *dst);
00198       /// Read the raw y register into the provided buffer. @sa readXYZRaw
00199       int readYRaw(char *dst);
00200       /// Read the raw z register into the provided buffer. @sa readXYZRaw
00201       int readZRaw(char *dst);
00202       
00203       /**
00204        * Read the x, y, and z signed counts of the MMA8452 axes.
00205        * 
00206        * Count resolution is either 8 bits or 12 bits, and the range is either +-2G, +-4G, or +-8G
00207        * depending on settings. The number of counts per G are 1024, 512, 256 for 2,4, and 8 G
00208        * respectively at 12 bit resolution and 64, 32, 16 for 2, 4, and 8 G respectively at
00209        * 8 bit resolution.
00210        * 
00211        * This function queries the MMA8452 and returns the signed counts for each axes.
00212        *
00213        * @param x Pointer to integer to store x count
00214        * @param y Pointer to integer to store y count
00215        * @param z Pointer to integer to store z count
00216        * @return 0 on success, 1 on failure.
00217        */
00218       int readXYZCounts(int *x, int *y, int *z);
00219       
00220       /// Read the x axes signed count. @sa readXYZCounts
00221       int readXCount(int *x);
00222       /// Read the y axes signed count. @sa readXYZCounts
00223       int readYCount(int *y);
00224       /// Read the z axes signed count. @sa readXYZCounts
00225       int readZCount(int *z);
00226       
00227       /**
00228        * Read the x, y, and z accelerations measured in G.
00229        *
00230        * The measurement resolution is controlled via setBitDepth which can
00231        * be 8 or 12, and by setDynamicRange, which can be +-2G, +-4G, or +-8G.
00232        *
00233        * @param x A pointer to the double to store the x acceleration in.
00234        * @param y A pointer to the double to store the y acceleration in.
00235        * @param z A pointer to the double to store the z acceleration in.
00236        *
00237        * @return 0 on success, 1 on failure.
00238        */
00239       int readXYZGravity(double *x, double *y, double *z);
00240       
00241       /// Read the x gravity in G into the provided double pointer. @sa readXYZGravity
00242       int readXGravity(double *x);
00243       /// Read the y gravity in G into the provided double pointer. @sa readXYZGravity
00244       int readYGravity(double *y);
00245       /// Read the z gravity in G into the provided double pointer. @sa readXYZGravity
00246       int readZGravity(double *z);
00247       
00248       /// Returns 1 if data has been internally sampled (is available) for all axes since last read, 0 otherwise.
00249       int isXYZReady();
00250       /// Returns 1 if data has been internally sampled (is available) for the x-axis since last read, 0 otherwise.
00251       int isXReady();
00252       /// Returns 1 if data has been internally sampled (is available) for the y-axis since last read, 0 otherwise.
00253       int isYReady();
00254       /// Returns 1 if data has been internally sampled (is available) for the z-axis since last read, 0 otherwise.
00255       int isZReady();
00256             
00257       /** 
00258        * Reads a single byte from the specified MMA8452 register.
00259        *
00260        * @param addr The internal register address.
00261        * @param dst The destination buffer address.
00262        * @return 1 on success, 0 on failure.
00263        */
00264       int readRegister(char addr, char *dst);
00265       
00266       /** 
00267        * Reads n bytes from the specified MMA8452 register.
00268        *
00269        * @param addr The internal register address.
00270        * @param dst The destination buffer address.
00271        * @param nbytes The number of bytes to read.
00272        * @return 1 on success, 0 on failure.
00273        */
00274       int readRegister(char addr, char *dst, int nbytes);
00275         
00276        /** 
00277         * Write to the specified MMA8452 register.
00278         *
00279         * @param addr The internal register address
00280         * @param data Data byte to write
00281         */    
00282       int writeRegister(char addr, char data);
00283       
00284        /** 
00285         * Write a data buffer to the specified MMA8452 register.
00286         *
00287         * @param addr The internal register address
00288         * @param data Pointer to data buffer to write
00289         * @param nbytes The length of the data buffer to write
00290         */    
00291       int writeRegister(char addr, char *data, int nbytes);
00292       
00293       int setDynamicRange(DynamicRange range, int toggleActivation=1);
00294       int setBitDepth(BitDepth depth, int toggleActivation=1);
00295       int setDataRate(DataRateHz dataRate, int toggleActivation=1);
00296       
00297       DynamicRange getDynamicRange();
00298       DataRateHz getDataRate();
00299       BitDepth getBitDepth();
00300       
00301       #ifdef MMA8452_DEBUG
00302       void debugRegister(char reg);
00303       #endif
00304    
00305     private:
00306       /**
00307        * Reads the specified register, applies the mask with logical AND, logical ORs the value
00308        * and writes back the result to the register. If toggleActivation is set to true then the
00309        * device is put in standby before the operation, and activated at the end.
00310        * Setting it to false is useful for setting options on a device that you want to keep in
00311        * standby.
00312        */
00313       int maskAndApplyRegister(char reg, char mask, char value, int toggleActivation);
00314       
00315       /// Reads the specified register, applies the mask with logical AND, and writes the result back.
00316       int logicalANDRegister(char addr, char mask);
00317       /// Reads the specified register, applies the mask with logical OR, and writes the result back.
00318       int logicalORRegister(char addr, char mask);
00319       /// Reads the specified register, applies the mask with logical XOR, and writes the result back.
00320       int logicalXORRegister(char addr, char mask);
00321       
00322       /// Converts the 12-bit two's complement number in buf to a signed integer. Returns the integer.
00323       int twelveBitToSigned(char *buf);
00324       /// Converts the 8-bit two's complement number in buf to a signed integer. Returns the integer.
00325       int eightBitToSigned(char *buf);
00326       
00327       /// Converts a count to a gravity using the supplied countsPerG. Returns the gravity.
00328       double convertCountToGravity(int count, int countsPerG);
00329       
00330       /// Reads the register at addr, applies the mask with logical AND, and returns the result.
00331       char getMaskedRegister(int addr, char mask);
00332       
00333       /// Get the counts per G for the current settings of bit depth and dynamic range.
00334       int getCountsPerG();
00335     
00336       I2C _i2c;
00337       int _frequency;
00338       int _readAddress;
00339       int _writeAddress;
00340       
00341       BitDepth _bitDepth;
00342       DynamicRange _dynamicRange;       
00343 };