AnsweredAssumed Answered

ADXL345 Dev. Board datalogger (UG-065) - Missing milliseconds at 400Hz

Question asked by Aris on Mar 7, 2016
Latest reply on Mar 17, 2016 by Aris

Hey guys!

 

I'm having a problem with this product and i'm not sure if there's something i'm doing wrong or not..

I'm uploading .hex files using ARMWSDv1.8.

Up to 200 Hz i'm counting 200 measurements/sec (all good).

 

But when i upload 400 Hz - 8G (full res. or 10bit) i can see that each second does NOT have exactly 400 measurements.

 

There are some specific 'groups of seconds' that are ok in total (eg. 4 seconds = 1600measurements = 4*400), but not all same groups (eg next 4 seconds) have same measurements (some have 1500, others have 1644 etc).

 

Isn't the timer precise or what am i not getting here?

Should i suppose that every 400measurements are 1 sec of time (and just not take into consideration the second matrix column)?

 

Example of SD card Matrix (just a few rows):

ndx:    HR:MN:SC:1/128s:    x:    y:    z:

473,    00:00:07:057,    68,    -12,    226

474,    00:00:07:057,    69,    -11,    228

475,    00:00:07:058,    69,    -11,    226

476,    00:00:07:058,    69,    -14,    224

477,    00:00:07:058,    72,    -13,    223

478,    00:00:07:058,    70,    -14,    222

479,    00:00:07:059,    68,    -14,    223

 

Anybody has encountered the same problem?

Meybe neilzhao knows something..?

 

Big thanx!

Outcomes