LIS2DE12 Sleep-to-wake and Return-to-sleep feature

[Fahad Mirza]

Posted on November 21, 2017 at 23:34

I like to use the

Sleep-to-wake and Return-to-sleep feature of the LIS2DE12. I am wondering what axis value is compared with the threshold value (ACT_THS). Can I select the axis? The

http://www.st.com/content/ccc/resource/technical/document/datasheet/group0/72/cb/80/a7/5e/fe/46/9d/DM00153214/files/DM00153214.pdf/jcr:content/translations/en.DM00153214.pdf

doesn't say much!

#sleep #accelerometer #mems

[Miroslav BATEK]

Posted on November 22, 2017 at 08:36

All three axis are compered with the threshold value, you can't select them.

[Fahad Mirza]

Posted on November 22, 2017 at 23:19

Any idea how can I use this feature to detect activity-inactivity? I can't use HP filter on the axes to 'zero-down' the acceleration value because I am actually measuring tilt. Filtered data will only detect the change.

[Miroslav BATEK]

Posted on November 23, 2017 at 09:50

For acitivity-inactivity you can set the threshold above 1g so it will work without any HP filter.

You can also use HP filter for interrupt generator 1/2 and implement the activity-inactivity (or power save mode) with help of you microcontroler. You can wake up the system using threshold interrupt (with HP filter) keep it alive and if there is no more interrupt during some time reduce the ODR and switch the device to power save mode.