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ADXL 372. Switch from Instant On Mode to Wake Up Mode?

Question asked by Teliarg on Feb 9, 2018
Latest reply on Feb 13, 2018 by jwang



For a project, I have to create a "chocs detector" with a huge autonomy (1 year if possible). I've chosen to work with the ADXL 372.

Here is a quick explanation of my project idea before asking my question.


The aim is to save the chocs of a machine during one year and to analyse it after. In order to have the less consumption possible (no battery reloading possible), the idea is this one : Stay in Wake Up Mode while the machine isn't moving, and switch into Instant On Mode when a little movement is detected (thanks to Activity detection in Wake Up Mode). The activity detection will also "wake up" the microcontroller with an interruption (which were in Hibernate Mode). So the system is now ready to measure a choc with the autonomous switch of ADXL 372 into Measurement Mode.


When the measure is made, the result is send to the microcontroller which will save this measure.

After that, the microcontroller will send an instruction to the ADXL 372 to switch in Wake Up Mode and the microcontroller will go back in Hibernate Mode. Etc..



My issue is in the case where mouvement is detected but without any chocs. I don't want that the system stay in Instant On Mode during too much time?

The easiest way would be to add a timer in the microcontroller and to stop the Instant On Mode with an instruction after x seconds if there are no chocs but still in order to consume the less possible, I would like to switch the microcontrolleur in a semi-sleep mode (Flexi Mode) during the measure and only go back in Active Mode when the measure is made. In this Flexi Mode, the core of the microcontroller is off so it's impossible to use a timer.


My question is : Is it possible to switch from Instant On Mode to Wake Up Mode without microcontroller (with a kind of timer in ADXL?)? Or to use the inactivity detection in Instant On Mode? This inactivty detection could be send to the microcontroller to "say" to it that there are no chocs and that it could go back in Hibernate Mode.


I suppose you guessed it but my English isn't perfect and It's difficult for me to understand that with the datasheets.

I already thank you for having read my long post!