Hi,

I'm porting a medical application which measures activity levels of seniors using the N900 accelerometer. It requires accurately timed accelerometer samples. I've looked at the accelerometer driver and it uses an interrupt to read the accelerometer which is likely to result in precise sample times, but that precision in timing is lost when accessing the accelerometer data via the DBUS or via it's file device interface because DBUS calls can be delayed by system events, as can reads from the file device. I've tried both and the jitter is unacceptable (4 milliseconds variation at best when no other apps are running and 50 milliseconds with an audio app running with a 100Hz sample rate). Perhaps the accelerometer data should include a timestamp from the driver?
Or maybe I can just assume a precise interval between readings if I read faster than the default sample rate of 100Hz (if I read data at 200Hz each reading should repeat twice so I'd be able to tell individual readings apart as long as they were changing)?

Ron