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ADXL345: Question about reference values for AC-coupled mode

Question asked by foresightyj on May 30, 2012
Latest reply on Jun 4, 2012 by foresightyj

Hi guys,

 

ADXL345 has AC-coupled mode for both ACTIVITY and INACTIVITY interrupts. According to the datasheet, this is how reference values are defined:

 

"In ac-coupled operation for activity detection, the acceleration value at the start of activity detection is taken as a reference value."

 

My question is:

For example, if I only enable ACTVITIY interrupt in the AC-coupled mode with a threshold of 0.5g. The purpose is to if the orientation of the ADXL345 is constantly changed, assuming the ADXL345 is embedded into a watch and I want to know if the user's wrist is moving. Does it mean that this reference value is only taken once, the moment I activated the ACTIVITY interrupt? Or every time an ACTIVITY interrupt is generated, a new reference value is taken?

 

Thanks for any inputs.

 

YJ

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