Revision 0:3ae1e808e61c, committed 2014-04-07

Comitter:

JimCarver

Date:

Mon Apr 07 00:59:06 2014 +0000

Child:

1:ff30cc4759b4

Commit message:

Rev 0.1 Simple operation of just X, Y, Z values in floating point G's

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MMA8652.cpp	Mon Apr 07 00:59:06 2014 +0000
@@ -0,0 +1,65 @@
+ #include "MMA8652.h"
+ 
+MMA8652::MMA8652(PinName sda, PinName scl) : _i2c(sda, scl) {
+ 
+    begin();
+}
+              
+void MMA8652::RegRead( char reg, char * d, int len)
+{
+    char cmd[1];
+    cmd[0] = reg;
+char i2c_addr = MMA8652_SLAVE_ADDR;
+_i2c.write( i2c_addr, cmd, 1);
+_i2c.read ( i2c_addr, d, len);
+}
+
+void MMA8652::begin(void)
+{
+    char data[2];
+    // write 0000 0000 = 0x00 to accelerometer control register 1 to place MMA8652 into
+    // standby
+    // [7-1] = 0000 000
+    // [0]: active=0
+    data[0] = MMA8652_CTRL_REG1;
+    data[1] = 0x00;
+    _i2c.write( MMA8652_SLAVE_ADDR, data, 2);
+    
+    // write 0000 0001= 0x01 to XYZ_DATA_CFG register
+    // [7]: reserved
+    // [6]: reserved
+    // [5]: reserved
+    // [4]: hpf_out=0
+    // [3]: reserved
+    // [2]: reserved
+    // [1-0]: fs=00 for accelerometer range of +/-2g range with 0.244mg/LSB
+    data[0] = MMA8652_XYZ_DATA_CFG;
+    data[1] = 0x00;
+    _i2c.write( MMA8652_SLAVE_ADDR, data, 2);
+
+    // write 0000 1101 = 0x0D to accelerometer control register 1
+    // [7-6]: aslp_rate=00
+    // [5-3]: dr=100 for 50Hz data rate
+    // [2]: 0
+    // [1]: 0
+    // [0]: active=1 to take the part out of standby and enable sampling
+    data[0] = MMA8652_CTRL_REG1;
+    data[1] = 0x21;
+    _i2c.write( MMA8652_SLAVE_ADDR, data, 2);
+}
+
+void MMA8652::ReadXYZ(float * a)
+{
+    char d[7];
+    int16_t t[6];
+
+    RegRead( MMA8652_STATUS, d, 7);
+    t[0] = ((d[1] * 256) + ((unsigned short) d[2]));
+    t[1] = ((d[3] * 256) + ((unsigned short) d[4]));
+    t[2] = ((d[5] * 256) + ((unsigned short) d[6]));
+
+    a[0] = (float) t[0] / 16384.0;
+    a[1] = (float) t[1] / 16384.0;
+    a[2] = (float) t[2] / 16384.0;
+  
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MMA8652.h	Mon Apr 07 00:59:06 2014 +0000
@@ -0,0 +1,65 @@
+#ifndef MMA8652_H
+#define MMA8652_H
+
+#include "mbed.h"
+
+
+// MMA8652 Slave Address
+#define MMA8652_SLAVE_ADDR 0x3A
+
+// MMA8652 internal register addresses
+#define MMA8652_STATUS 0x00
+#define MMA8652_WHOAMI 0x0D
+#define MMA8652_XYZ_DATA_CFG 0x0E
+#define MMA8652_CTRL_REG1 0x2A
+#define MMA8652_WHOAMI_VAL 0x4A
+
+class MMA8652
+{
+public:
+    /**
+    * MPL3115A2 constructor
+    *
+    * @param sda SDA pin
+    * @param sdl SCL pin
+    * @param addr addr of the I2C peripheral
+    */
+    MMA8652(PinName sda, PinName scl);
+    
+    /**
+    * Get the value of the WHO_AM_I register
+    *
+    * @returns DEVICE_ID value == ??
+    */
+    //uint8_t getDeviceID();
+    
+    /**
+    * Return the STATUS register value
+    *
+    * @returns STATUS register value
+    */
+    //unsigned char getStatus( void);
+    
+    /**
+    * Get the Accelerometer & Magnetometer values
+    * Accelerometer data is in G's
+    * MAgnetometer Data is in microteslas
+    *
+    * @returns altimeter value as float
+    */
+    void ReadXYZ(float * a);
+      
+
+private:
+
+    I2C _i2c;
+    /** Set the device in active mode
+    */
+    void begin( void);
+    
+    void RegRead( char reg, char * d, int len);
+
+
+};
+
+#endif