Ashley Mills / MMA8452

Library for driving the MMA8452 accelerometer over I2C

Dependents:   MMA8452_Test MMA8452_Demo Dualing_Tanks IMU-Controlled_MP3_Player ... more

Here is a simple example:

#include "mbed.h"
#include "MMA8452.h"

int main() {
   Serial pc(USBTX,USBRX);
   pc.baud(115200);
   double x = 0, y = 0, z = 0;

   MMA8452 acc(p28, p27, 40000);
   acc.setBitDepth(MMA8452::BIT_DEPTH_12);
   acc.setDynamicRange(MMA8452::DYNAMIC_RANGE_4G);
   acc.setDataRate(MMA8452::RATE_100);
   
   while(1) {
      if(!acc.isXYZReady()) {
         wait(0.01);
         continue;
      }
      acc.readXYZGravity(&x,&y,&z);
      pc.printf("Gravities: %lf %lf %lf\r\n",x,y,z);
   }
}

An easy way to test that this actually works is to run the loop above and hold the MMA8452 parallel to the ground along the respective axis (and upsidedown in each axis). You will see 1G on the respective axis and 0G on the others.

Diff: MMA8452.h

Revision:
16:d6dde2318edc
Parent:
15:7620a11149b8
Child:
17:6e4232c421c0
--- a/MMA8452.h	Wed Mar 05 15:36:03 2014 +0000
+++ b/MMA8452.h	Wed Mar 05 16:47:13 2014 +0000
@@ -106,6 +106,9 @@
 
 // status masks and shifts
 #define MMA8452_STATUS_ZYXDR_MASK 0x08
+#define MMA8452_STATUS_ZDR_MASK 0x04
+#define MMA8452_STATUS_YDR_MASK 0x02
+#define MMA8452_STATUS_XDR_MASK 0x01
  
 class MMA8452         
 {        
@@ -244,6 +247,7 @@
       int twelveBitToSigned(char *buf);
       int eightBitToSigned(char *buf);
       double convertCountToGravity(int count, int countsPerG);
+      char getMaskedRegister(int reg, char mask);
     
       I2C _i2c;
       int _frequency;