CR95HF: Tag removal detection

[g23]

Posted on May 06, 2014 at 11:42

Detecting the presence of tags with the CR95HF works fine. But is it possible to detect the removal of a tag within the antenna field?

I was thinking about polling the Tag Detect command with a very short timeout. As long as the wakeup event is ''tag'' and the timeout doesn't occur the tag is still present. But for my application power consumption is very important, meaning I want to stay in Sleep as long as possible.

What�s the best way to implement the detection of a tag removal?

#cr95hf #cr95hf #cr95hf-iso15693 #tag-detect #an3433

[Anais GALLIGANI]

Posted on May 19, 2014 at 10:21

Hello,

The tag detection process is looking for a variation of the antenna loading ,

Playing with the calibration state and the detection limits  you must be able to define a set-up which detect presence or absence of tag .

Please look at the dedicated AN3433

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/application_note/DM00034250.pdf

I hope this is helping,

Thx a lot,

Have a nice day,

BR,

ST NFC/RFID dynamic tag support