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:
16:d6dde2318edc
Parent:
14:0602b45ca70f
Child:
17:6e4232c421c0
--- a/MMA8452.cpp	Wed Mar 05 15:36:03 2014 +0000
+++ b/MMA8452.cpp	Wed Mar 05 16:47:13 2014 +0000
@@ -121,14 +121,31 @@
    );
 }
 
-int MMA8452::isXYZReady() {
+char MMA8452::getMaskedRegister(int reg, char mask) {
    char rval = 0;
-   if(readRegister(MMA8452_STATUS,&rval)) {
+   if(readRegister(reg,&rval)) {
       return 0;
    }
-   return (rval&MMA8452_STATUS_ZYXDR_MASK);
+   return (rval&mask);
+}
+
+int MMA8452::isXYZReady() {
+   return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_ZYXDR_MASK)>0;
+}
+
+int MMA8452::isXReady() {
+   return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_XDR_MASK)>0;
 }
- 
+
+int MMA8452::isYReady() {
+   return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_YDR_MASK)>0;
+}
+
+int MMA8452::isZReady() {
+   return getMaskedRegister(MMA8452_STATUS,MMA8452_STATUS_ZDR_MASK)>0;
+}
+
+
 int MMA8452::getDeviceID(char *dst) {
    return readRegister(MMA8452_WHO_AM_I,dst);
 }