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.

Files at this revision

API Documentation at this revision

Revision 7:8aa5123d403f, committed 2013-10-17

Comitter:
nherriot
Date:
Thu Oct 17 09:40:10 2013 +0000
Parent:
5:b3d0abd97e55
Child:
8:89272163f395
Commit message:
Fixing bug in write IIC methods -where register pointer was being reset to 0 as the write function was not doing a repeated 'start' for multiple register reads.... :-)

Changed in this revision

MMA8452.cpp Show annotated file Show diff for this revision Revisions of this file 
--- a/MMA8452.cpp	Wed Oct 16 18:55:16 2013 +0000
+++ b/MMA8452.cpp	Thu Oct 17 09:40:10 2013 +0000
@@ -240,7 +240,7 @@
     xaxis_register[0] = OUT_X_MSB;                          // this is the register we want to get data from
     //signed short s = 0;
     
-    if(m_i2c.write(mcu_address,xaxis_register,1) == 0)
+    if(m_i2c.write(mcu_address,xaxis_register,1,true) == 0)
     {
         if(m_i2c.read(mcu_address,xaxis_buffer,2) == 0)
         {
@@ -280,7 +280,7 @@
     yaxis_register[0] = OUT_Y_MSB;                          // this is the register we want to get data from
     //signed short s = 0;
     
-    if(m_i2c.write(mcu_address,yaxis_register,1) == 0)
+    if(m_i2c.write(mcu_address,yaxis_register,1,true) == 0)
     {
         if(m_i2c.read(mcu_address,yaxis_buffer,2) == 0)
         {
@@ -321,7 +321,7 @@
     zaxis_register[0] = OUT_Z_MSB;                          // this is the register we want to get data from
     //signed short s = 0;
     
-    if(m_i2c.write(mcu_address,zaxis_register,1) == 0)
+    if(m_i2c.write(mcu_address,zaxis_register,1,true) == 0)
     {
         //if(m_i2c.read(mcu_address,zaxis_buffer,2) == 0)
         if(m_i2c.read(mcu_address,zaxis,2) == 0)