On Mon, 12 Jan 2009 14:33:00 +0100 Stefan Schmidt <[email protected]> wrote:
> > | Threshold for accels. We finally like to ship the great accel > > | gesture application from our GSoC student, but it would only be > > | really useful if we could set a threshold instead of parsing > > | data all the time and burn cpu. > > > > This is done by Simon Kagstrom some time ago, it's down in /sys. > > Maybe Simon can give some advice. > > Cool, that must have slipped through our radar. Simon, is the > threshold working and if how can we use it? I sneaked it in low under the radar at the kernel mailing list ~two months ago or so :-) It's simple to use, just write the threshold value in mg's to /sys/.../lis302dl.1/threshold. Writing zero will revert to the default behavior and generate each data item. To get a feeling of how it works, just hexdump the accelerometer input device and raise the threshold until the device no longer generates data when lying still on the table. If you drop it to the floor and it doesn't generate data, you set the threshold too high. Or the phone broke. In the long run, I think an adaptive daemon could be used to export the accelerometer data with thresholds. The threshold can be a slight problem if the user use slow, smooth moves (although I think the duration parameter can help with that). So I think the daemon could set the threshold high at start, wake up when the user starts moving around the phone and set the threshold to zero until the device stops moving. The issue of users walking around with the phone with accelerometer-dependent apps is ... an interesting problem. // Simon
