GPIO streaming timestamp not accurate

Comments

• Eric

  May 2016

  I do not see any issues exporting data past 1 minute on my Nexus 6 (Android M) and Nexus 7 (Android 5.1.1).

  
  

  Just to be clear, you can see 1 min worth of data on the graph but when you export the CSV file, you only receive ~40 seconds?
  

  
  

  
  
• udi_o

  May 2016

  Yes, I'm streaming 1 minute measured with external stop-watch, then I stop the streaming and save+email. 

  The final entries on the CSV file are:

  40.722

  40.755

  40.788

  40.821

  40.854

  40.887

  40.92

  
  

  The file consists in total 1242 rows of data which match ~40 seconds: 1242 X 0.033 = ~40

  
  
• Eric

  May 2016

  Does the graph show 1 minute worth of data?
• udi_o

  May 2016

  The graph shows 40 seconds but the actual duration was 60 seconds.

  It looks like the sampling rate is actually 0.050 and not 0.033
• Eric

  May 2016

  The sampling rate is 0.033s (30Hz).  If you run the sampling for longer, say 120 seconds, does the graph stop at 40 seconds?  If not, then it seems like your device is not capturing all data packets.
• udi_o

  May 2016

  1) Why should the graph stop at 40 seconds?

  2) Is the time-stamp calculated by the SampleAndroidApp regardless missing packets?

  3) The same fault occurred both with LG 5.5 and Samsung 4.3 devices, any suggestions / workaround?
• Eric

  May 2016

  1. It shouldn't so if it does, something is seriously wrong with the app
  2. Time stamps are based on number of samples received.  The were originally based on when the mobile device received the data but high frequency streams results in multiple data being received at the same time.
  3. You can try lowering the sampling frequency to 1Hz and increasing it until you see this error.