tmk_core/tool/mbed/mbed-sdk/libraries/tests/peripherals/MMA7660/MMA7660.cpp

   1 #include "MMA7660.h"
   2
   3 MMA7660::MMA7660(PinName sda, PinName scl, bool active) : _i2c(sda, scl)
   4 {
   5     setActive(active);
   6     samplerate = 64;
   7
   8 }
   9
  10 //Since the MMA lacks a WHO_AM_I register, we can only check if there is a device that answers to the I2C address
  11 bool MMA7660::testConnection( void )
  12 {
  13     if (_i2c.write(MMA7660_ADDRESS, NULL, 0) == 0 )
  14         return true;
  15     else
  16         return false;
  17 }
  18
  19 void MMA7660::setActive(bool state)
  20 {
  21     char modereg = read(MMA7660_MODE_R);
  22     modereg &= ~(1<<0);
  23
  24     //If it somehow was in testmode, disable that
  25     if (modereg && (1<<2)) {
  26         modereg &= ~(1<<2);
  27         write(MMA7660_MODE_R, modereg);
  28     }
  29
  30     modereg += state;
  31     write(MMA7660_MODE_R, modereg);
  32 }
  33
  34 void MMA7660::readData(int *data)
  35 {
  36     if (!active) {
  37         setActive(true);
  38         active = true;
  39         wait(0.012 + 1/samplerate); //Wait until new sample is ready, my experience is that 1/samplerate isnt needed, but datasheet says so
  40     }
  41
  42     char temp[3];
  43     bool alert;
  44
  45     do {
  46         alert = false;
  47         read(MMA7660_XOUT_R, temp, 3);
  48         for (int i = 0; i<3; i++) {
  49             if (temp[i] > 63)
  50                 alert = true;
  51             if (temp[i] > 31)
  52                 temp[i] += 128+64;
  53             data[i] = (signed char)temp[i];
  54         }
  55     } while (alert);
  56
  57     if (!active)
  58         setActive(false);
  59 }
  60
  61
  62 void MMA7660::readData(float *data)
  63 {
  64     int intdata[3];
  65     readData(intdata);
  66     for (int i = 0; i<3; i++)
  67         data[i] = intdata[i]/MMA7660_SENSITIVITY;
  68 }
  69
  70 float MMA7660::x( void )
  71 {
  72     return getSingle(0);
  73 }
  74
  75 float MMA7660::y( void )
  76 {
  77     return getSingle(1);
  78 }
  79
  80 float MMA7660::z( void )
  81 {
  82     return getSingle(2);
  83 }
  84
  85
  86 void MMA7660::setSampleRate(int samplerate)
  87 {
  88     setActive(false);                               //Not allowed to be active to change anything
  89     int rates[] = {120, 64, 32, 16, 8, 4, 2, 1};    //Alowed samplerates (and their number in array is also number required for MMA)
  90     int sampleLoc = 0, sampleError = 10000, temp;
  91     for (int i = 0; i<8; i++) {
  92         temp = abs( rates[i] - samplerate );
  93         if (temp<sampleError) {
  94             sampleLoc = i;
  95             sampleError=temp;
  96         }
  97     }
  98
  99     //Update the samplerate reg
 100     temp = read(MMA7660_SR_R);
 101     temp &= ~0x07;                                  //Awake sample rate are lowest 3 bit
 102     temp |= sampleLoc;
 103     write(MMA7660_SR_R, temp);
 104     this->samplerate = rates[sampleLoc];
 105     setActive(active);                              //Restore previous active state
 106 }
 107
 108
 109 MMA7660::Orientation MMA7660::getSide( void )
 110 {
 111     char tiltreg = read(MMA7660_TILT_R);
 112
 113     //We care about 2 LSBs
 114     tiltreg &= 0x03;
 115     if (tiltreg == 0x01)
 116         return MMA7660::Front;
 117     if (tiltreg == 0x02)
 118         return MMA7660::Back;
 119     return MMA7660::Unknown;
 120 }
 121
 122 MMA7660::Orientation MMA7660::getOrientation( void )
 123 {
 124     char tiltreg = read(MMA7660_TILT_R);
 125
 126     //We care about bit 2, 3 and 4 (counting from zero)
 127     tiltreg &= 0x07<<2;
 128     tiltreg >>= 2;
 129     if (tiltreg == 0x01)
 130         return MMA7660::Left;
 131     if (tiltreg == 0x02)
 132         return MMA7660::Right;
 133     if (tiltreg == 0x05)
 134         return MMA7660::Down;
 135     if (tiltreg == 0x06)
 136         return MMA7660::Up;
 137     return MMA7660::Unknown;
 138 }
 139
 140
 141
 142 //////////////////////////////////////////////
 143 ///////////////PRIVATE////////////////////////
 144 //////////////////////////////////////////////
 145
 146
 147 void MMA7660::write(char address, char data)
 148 {
 149     char temp[2];
 150     temp[0]=address;
 151     temp[1]=data;
 152
 153     _i2c.write(MMA7660_ADDRESS, temp, 2);
 154 }
 155
 156 char MMA7660::read(char address)
 157 {
 158     char retval;
 159     _i2c.write(MMA7660_ADDRESS, &address, 1, true);
 160     _i2c.read(MMA7660_ADDRESS, &retval, 1);
 161     return retval;
 162 }
 163
 164 void MMA7660::read(char address, char *data, int length)
 165 {
 166     _i2c.write(MMA7660_ADDRESS, &address, 1, true);
 167     _i2c.read(MMA7660_ADDRESS, data, length);
 168 }
 169
 170 float MMA7660::getSingle( int number )
 171 {
 172     if (!active) {
 173         setActive(true);
 174         wait(0.012 + 1/samplerate); //Wait until new sample is ready
 175     }
 176
 177     signed char temp;
 178     bool alert;
 179
 180     do {
 181         alert = false;
 182         temp = read(MMA7660_XOUT_R + number);
 183         if (temp > 63)
 184             alert = true;
 185         if (temp > 31)
 186             temp += 128+64;
 187     } while (alert);
 188
 189     if (!active)
 190         setActive(false);
 191
 192     return temp / MMA7660_SENSITIVITY;
 193 }