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.cpp

Revision:
4:27aa3cd43234
Parent:
3:ffb0b1650ca2
Child:
5:b3d0abd97e55
--- a/MMA8452.cpp	Wed Oct 16 14:11:04 2013 +0000
+++ b/MMA8452.cpp	Wed Oct 16 16:26:26 2013 +0000
@@ -290,10 +290,11 @@
     
     if(m_i2c.write(mcu_address,zaxis_register,1) == 0)
     {
-        if(m_i2c.read(mcu_address,zaxis_buffer,2) == 0)
+        //if(m_i2c.read(mcu_address,zaxis_buffer,2) == 0)
+        if(m_i2c.read(mcu_address,zaxis,2) == 0)
         {
             //strcpy(yaxis, yaxis_buffer);
-            memcpy(zaxis, zaxis_buffer, 2);
+            //memcpy(zaxis, zaxis_buffer, 2);
             //yaxis[0] = 0x00;                        // make sure the array is set to zero
             //yaxis[1] = 0x00;
             //s = *reinterpret_cast<short*>(&xaxis);