Diff: MMA8452.h

Revision:

0:df3b9e41edf3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MMA8452.h	Sun Mar 08 15:31:02 2015 +0000
@@ -0,0 +1,110 @@
+/**
+@file MMA8452.h
+
+@brief Header file containing member functions and variables
+
+*/
+
+#ifndef MMA8452_H
+#define MMA8452_H
+
+// MMA8452 address is 0x1D by default (see EAGLE schematic of breakout - SA = 1)
+#define MMA8452_W_ADDRESS   0x3A
+#define MMA8452_R_ADDRESS   0x3B
+// Register Descriptions - p18 datasheet
+#define OUT_X_MSB           0x01
+#define WHO_AM_I            0x0D
+#define CTRL_REG1           0x2A
+#define XYZ_DATA_CFG        0x0E
+
+typedef struct Acceleration Acceleration;
+struct Acceleration {
+    float x;
+    float y;
+    float z;
+};
+
+#include "mbed.h"
+
+/**
+@brief Library for interfacing with MMA8452 I2C Accelerometer
+
+@see http://www.freescale.com/files/sensors/doc/data_sheet/MMA8452Q.pdf
+@see https://www.sparkfun.com/products/12756
+
+@brief Revision 1.0
+
+@author Craig A. Evans
+@date   March 2015
+ *
+ * Example:
+ * @code
+
+#include "mbed.h"
+#include "MMA8452.h"
+
+MMA8452 mma8452(p28,p27);  // SDA, SCL
+Serial serial(USBTX,USBRX);
+
+int main() {
+
+    mma8452.init();  // 100 Hz update rate, ±4g scale
+
+    Acceleration acceleration;  // Accleration structure declared in MMA8452 class
+
+    while(1) {
+
+        acceleration = mma8452.readValues();   // read current values and print over serial port
+        serial.printf("x = %.2f g y = %.2f g z = %.2f g\n",acceleration.x,acceleration.y,acceleration.z);
+        wait(0.1);   // short delay until next reading
+
+    }
+
+}
+
+
+ * @endcode
+ */
+class MMA8452
+{
+
+public:
+    /** Create a MMA8452 object connected to the specified pins
+    *
+    * @param sdaPin - mbed SDA pin
+    * @param sclPin - mbed SCL pin
+    *
+    */
+    MMA8452(PinName sdaPin, PinName sclPin);
+
+    /** Initialise accelerometer
+    *
+    *   Powers up the accelerometer, sets 100 Hz update rate and ±4g scale
+    */
+    void init();
+
+    /** Get values of acceleration
+    *
+    *   Reads the x,y,z values in g's
+    *   @returns an Acceleration structure with x,y,z members (float)
+    */
+    Acceleration readValues();
+
+
+private:
+    void sendByteToRegister(char byte,char reg);
+    char readByteFromRegister(char reg);
+    void readBytesFromRegister(char reg,int numberOfBytes,char bytes[]);
+    void error();
+
+public:
+
+private:  // private variables
+    I2C*    i2c;
+    BusOut*  leds;
+
+};
+
+
+
+#endif
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