Accelerometer SensorEvent timestamp

Question

Im currently working on a android application.. I have to log the accelerometer sensor event coordinate with event time. I got the sensor event timestamp like "3497855005850" but i am not able to convert event timestamp into user readable date time format.Thanks in advance

How can i convert SensorEvent timestamp to unix timestamp?

Answer 1

The sensor timestamp is actually nanoseconds of uptime, not system time in nanoseconds. See SensorEvent.timestamp to absolute (utc) timestamp?.

In theory, you can convert sensor timestamp to time in milliseconds using:

long timeInMillis = (new Date()).getTime()                      + (sensorEvent.timestamp - System.nanoTime()) / 1000000L; 

You could even bracket the (new Date()).getTime() call with two System.nanoTime() calls and average them to get closer to the actual offset.

Then you can format the sensor time as date and time.

Answer 2

You can set referent time variables in your onSensorChanged(SensorEvent) function.

Reference for current time and event time. When event arrives subtract sensor referent time from event time and you will have difference in nanoseconds. You can add that difference divided by 1,000,000 to current time reference to get event time in milliseconds.
Error with calculating this can be max 0.5 milliseconds for one event. You can minimize error by changing referent times occasionally.

private long sensorTimeReference = 0l; private long myTimeReference = 0l;  public void onSensorChanged(SensorEvent event) {     // set reference times     if(sensorTimeReference == 0l && myTimeReference == 0l) {         sensorTimeReference = event.timestamp;         myTimeReference = System.currentTimeMillis();     }     // set event timestamp to current time in milliseconds     event.timestamp = myTimeReference +          Math.round((event.timestamp - sensorTimeReference) / 1000000.0);     // some code... }