Initial implementation of iAcceleration

Signed-off-by: Serban Waltter <serban.waltter@rinftech.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/mma7455/mma7455.cxx

@@ -140,6 +140,46 @@ std::vector<short> MMA7455::readData() {
     return v;
 }
 
+std::vector<float> MMA7455::getAcceleration() {
+    std::vector<float> v(3);
+     accelData xyz;
+    int nBytes = 0;
+
+    /*do {
+        nBytes = i2cReadReg (MMA7455_STATUS, &data, 0x1);
+    } while ( !(data & MMA7455_DRDY) && nBytes == mraa::SUCCESS);
+
+    if (nBytes == mraa::SUCCESS) {
+        std::cout << "NO_GDB :: 1" << std::endl;
+        return mraa::SUCCESS;
+    }*/
+
+    nBytes = i2cReadReg (MMA7455_XOUTL, (unsigned char *) &xyz, 0x6);
+    if (nBytes == 0) {
+        std::cout << "NO_GDB :: 2" << std::endl;
+        //return mraa::ERROR_UNSPECIFIED;
+    }
+
+    if (xyz.reg.x_msb & 0x02) {
+        xyz.reg.x_msb |= 0xFC;
+    }
+
+    if (xyz.reg.y_msb & 0x02) {
+        xyz.reg.y_msb |= 0xFC;
+    }
+
+    if (xyz.reg.z_msb & 0x02) {
+        xyz.reg.z_msb |= 0xFC;
+    }
+
+    // The result is the g-force in units of 64 per 'g'.
+    v[0] = (float)xyz.value.x;
+    v[1] = (float)xyz.value.y;
+    v[2] = (float)xyz.value.z;
+
+    return v;
+}
+
 int
 MMA7455::i2cReadReg (unsigned char reg, uint8_t *buffer, int len) {
     if (mraa::SUCCESS != m_i2ControlCtx.writeByte(reg)) {

src/mma7455/mma7455.hpp

@@ -27,6 +27,8 @@
 #include <vector>
 #include <mraa/i2c.hpp>
 
+#include <interfaces/iAcceleration.hpp>
+
 #define ADDR               0x1D // device address
 
 // Register names according to the datasheet.
@@ -171,7 +173,7 @@ typedef union {
  * @image html mma7455.jpg
  * @snippet mma7455.cxx Interesting
  */
-class MMA7455 {
+class MMA7455: virtual public iAcceleration {
     public:
         /**
          * Instantiates an MMA7455 object
@@ -216,6 +218,13 @@ class MMA7455 {
          */
         std::vector<short> readData ();
 
+        /**
+         * get acceleration values
+         * 
+         * @return stl vector of size 3 representing the 3 axis
+         */
+        virtual std::vector<float> getAcceleration();
+
         /**
          * Internal function for reading I2C data
          *