Problems Reading Accelerometer Device

[Michael Tansella]

Hi,

I want to read out the Acc device and for me it is important to get really 
every measurement.

I read the wiki and the gestures source code but it didnt't help.
I set the samplerate to 400 Hz and though I think the time between two (x y z 
separator) measurements should be ca 2,5 ms, but in my logfile you can see that 
there are sometimes 30 ms. So I think I loose some values.

Any idea what I'm doing wrong?
Greets
Michael

------------------------------------------------------------------------------------------------------------------
Code:

///* reading the accelerometer Reports
void MokoAcc::run()
{
	const unsigned int ReportLength = 16;
  	unsigned char Report[ReportLength];
    while (GoOnFlag)
    {
    	int ReadLength = read(AccDevice, Report, ReportLength);
	//First 4 Bytes -> seconds
       	int Seconds = *(int *)(Report + 0);
       	//next 4 Bytes -> useconds
	int uSeconds = *(int *)(Report + 4);     
	// conversion to mseconds
	float mSeconds = uSeconds/1000.0;
	// next 2 Bytes: Rel=0 -> Separator Rel=2 -> Message
        unsigned short int Rel = *(unsigned short int *)(Report + 8);
	// next 2 Bytes: Axis Index 0->X  1->Y 2->Z
    	unsigned short int AxisIndex = *(unsigned short int *)(Report + 10);
	// next 4 Bytes: ACC Value in milli G
    	int ValueMG = *(int *)(Report + 12);
    	// Write to LogFile  
	AccLogFile<<"time: "<<Seconds<<" s"<<mSeconds<<"ms"<<"Rel:"<<Rel<<"Axisindex: 
	"<<AxisIndex<<" Value: "<<ValueMG<<" Timer dt: "<<ReadTime.elapsed()<<"ms\n";
	// Restart Qt Time (measures time for one loop)
	ReadTime.restart();
	}
}


------------------------------------------------------------------------------
Logfile:

time: 1227390487 s 897.588 ms  Rel: 2 Axis Index: 0 Value: -630 Timer dt: 14ms
time: 1227390487 s 897.622 ms  Rel: 2 Axis Index: 1 Value: -432 Timer dt: 0ms
time: 1227390487 s 897.628 ms  Rel: 2 Axis Index: 2 Value: 432 Timer dt: 0ms
time: 1227390487 s 897.636 ms  Rel: 0 Axis Index: 0 Value: 0 Timer dt: 0ms
time: 1227390487 s 917.129 ms  Rel: 2 Axis Index: 0 Value: -648 Timer dt: 19ms
time: 1227390487 s 917.158 ms  Rel: 2 Axis Index: 1 Value: -450 Timer dt: 0ms
time: 1227390487 s 917.164 ms  Rel: 2 Axis Index: 2 Value: 450 Timer dt: 1ms
time: 1227390487 s 917.172 ms  Rel: 0 Axis Index: 0 Value: 0 Timer dt: 0ms
time: 1227390487 s 956.199 ms  Rel: 2 Axis Index: 0 Value: -648 Timer dt: 38ms
time: 1227390487 s 956.223 ms  Rel: 2 Axis Index: 1 Value: -450 Timer dt: 0ms
time: 1227390487 s 956.229 ms  Rel: 2 Axis Index: 2 Value: 432 Timer dt: 1ms
time: 1227390487 s 956.235 ms  Rel: 0 Axis Index: 0 Value: 0 Timer dt: 0ms
time: 1227390488 s 5.068 ms  Rel: 2 Axis Index: 0 Value: -630 Timer dt: 51ms
time: 1227390488 s 5.103 ms  Rel: 2 Axis Index: 1 Value: -468 Timer dt: 0ms
time: 1227390488 s 5.11 ms  Rel: 2 Axis Index: 2 Value: 450 Timer dt: 6ms
time: 1227390488 s 5.117 ms  Rel: 0 Axis Index: 0 Value: 0 Timer dt: 0ms
time: 1227390488 s 19.714 ms  Rel: 2 Axis Index: 0 Value: -630 Timer dt: 6ms
time: 1227390488 s 19.744 ms  Rel: 2 Axis Index: 1 Value: -486 Timer dt: 0ms
time: 1227390488 s 19.75 ms  Rel: 2 Axis Index: 2 Value: 450 Timer dt: 0ms
time: 1227390488 s 19.758 ms  Rel: 0 Axis Index: 0 Value: 0 Timer dt: 0ms
time: 1227390488 s 36.8 ms  Rel: 2 Axis Index: 0 Value: -648 Timer dt: 17ms
time: 1227390488 s 36.824 ms  Rel: 2 Axis Index: 1 Value: -468 Timer dt: 0ms
time: 1227390488 s 36.829 ms  Rel: 2 Axis Index: 2 Value: 450 Timer dt: 0ms
time: 1227390488 s 36.836 ms  Rel: 0 Axis Index: 0 Value: 0 Timer dt: 0ms
time: 1227390488 s 110.09 ms  Rel: 2 Axis Index: 0 Value: -612 Timer dt: 77ms
time: 1227390488 s 110.134 ms  Rel: 2 Axis Index: 1 Value: -468 Timer dt: 1ms
time: 1227390488 s 110.14 ms  Rel: 2 Axis Index: 2 Value: 432 Timer dt: 0ms
time: 1227390488 s 110.147 ms  Rel: 0 Axis Index: 0 Value: 0 Timer dt: 0ms



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