Ashley Mills / Mbed 2 deprecated MMA8452_Test

A test program for the MMA8452 accelerometer

Dependencies:   MMA8452 mbed

The test program runs a bunch of tests for the MMA8452 accelerometer.

What is below is not the test program, but an example to whet your appetite about the library.

#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.

main.cpp

Committer:
ashleymills
Date:
2014-03-04
Revision:
0:0c17274c3b7c
Child:
1:e9981919b524

File content as of revision 0:0c17274c3b7c:

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

DigitalOut myled(LED1);

Serial pc(USBTX,USBRX);

#define LOG(...) pc.printf(__VA_ARGS__); pc.printf("\r\n");
#define LOGX(...) pc.printf(__VA_ARGS__);

void printByte(char b) {
   LOG("%d%d%d%d%d%d%d%d",
       (b&0x80)>>7,
       (b&0x40)>>6,
       (b&0x20)>>5,
       (b&0x10)>>4,
       (b&0x08)>>3,
       (b&0x04)>>2,
       (b&0x02)>>1,
       (b&0x01)
   );
}

void sampleMMA8452(MMA8452 *acc, int nsamples) {
   int samples = 0;
   int bufLen = 6;
   char buffer[6];
   memset(&buffer,0x00,bufLen);
   while(samples<nsamples) {
      if(!acc->isXYZReady()) {
         wait(0.01);
         continue;
      }
      memset(&buffer,0x00,bufLen);
      acc->readRawXYZ(buffer);
      LOGX("Sample %d of %d: ",samples,nsamples);
      for(int i=0; i<bufLen; i++) {
         LOGX("%.2x ",buffer[i]);
      }
      LOG(" ");
      samples++;
   }
}

int test() {
    MMA8452 acc(p28, p27, 40000);
    
    acc.debugRegister(MMA8452_CTRL_REG_1);
    
    LOG("Entering standby");
    if(acc.standby()) {
       LOG("Error putting MMA8452 in standby");
       return false;
    }
    
    acc.debugRegister(MMA8452_CTRL_REG_1);
    
    LOG("Activating MMA8452");
    if(acc.activate()) {
       LOG("Error activating MMA8452");
       return false;
    }
    
    // test setting dynamic range
    MMA8452::DynamicRange setRange = MMA8452::DYNAMIC_RANGE_UNKNOWN;
    MMA8452::DynamicRange readRange = MMA8452::DYNAMIC_RANGE_UNKNOWN;
    for(int i=0; i<=(int)MMA8452::DYNAMIC_RANGE_8G; i++) {
       setRange = (MMA8452::DynamicRange)i;
       if(acc.setDynamicRange(setRange)) {
          LOG("Error setting dynamic range. Failing.");
          return false;
       }
       readRange = acc.getDynamicRange();
       if(readRange!=setRange) {
          LOG("Read dynamic range: 0x%x does not match set: 0x%x",readRange,setRange);
          return false;
       }
       LOG("Success on dynamic range %d",i);
    }
    
    // test setting data rate
    for(int i=0; i<=(int)MMA8452::RATE_1_563; i++) {
       if(acc.setDataRate((MMA8452::DataRateHz)i)) {
          LOG("Error setting data rate. Failing.");
          return false;
       }
       if(acc.getDataRate()!=(MMA8452::DataRateHz)i) {
          LOG("Read data rate: 0x%x does not match set: 0x%x",acc.getDataRate(),(MMA8452::DataRateHz)i);
          return false;
       }
       LOG("Success on data rate %d",i);
    }
    
    // set bit depth to 8 and read some values
    LOG("Sampling at BIT_DEPTH_8");
    acc.setBitDepth(MMA8452::BIT_DEPTH_8);
    sampleMMA8452(&acc,10);
    
    // set bit depth to 12 and read some values
    LOG("Sampling at BIT_DEPTH_12");
    acc.setDataRate(MMA8452::RATE_100);
    acc.setBitDepth(MMA8452::BIT_DEPTH_12);
    sampleMMA8452(&acc,10);

    return true;
}

void loop() {
   while(1) {
      wait(1);
   }
}

int main() {
    pc.baud(115200);
    LOG("Begin");
    for(int i=0; i<20; i++) {
       LOG(" ");
    }
    if(!test()) {
       LOG("FAIL.");
       loop();
    }
    LOG("Tests passed");
    loop();
}