Reader to read multiple Hitag S tags at the same time (Reader with anticollision system)

[abderr]

Dear NXP-Community,

I hope this is the right place to ask.

I would like to build a 125 khz reader for Hitag S tags that allow to read at least 3 tags simultaneous within a range of 10 cm. The antenna may hav a size of 130x220 mm.

Can you suggest me which chip to use in my reader? HTRC110 can do the work?

Thanks

[KellyLi]

Hello @abderr 

HTRC110 is available for reading/writing Hitag S. But it may not work with multiple cards at the same time.
You may have misunderstood the concept of anti-collision. Normally, the reader can read and write only one RF card in the magnetic field at a time. However, when multiple cards enter the RF field of the reader at the same time, the reader needs to select a single card for read and write operations. This is anti-collision. Hope the above reply could help you.

Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.

Best regards,
Kelly
Technical Support
NXP Semiconductor

[abderr]

Thank you for your reply.

So if I understood correctly, when 3 tags enter the RF field at the same time, I have to send a select command to only one tag, then after reading its contents, I have to switch to another and so on ...

But to select a tag, I have to read its uuid first. How to retrieve the uuids of the 3 tags when they are in the RF field at the same time?

Thanks in advance

Cordially

[KellyLi · Accepted solution]

Hello @abderr 

The reader basically asks tags or cards to respond depending on their serial number or some other number.  If two or more tags respond, the reader asks again in a slightly different way, and then continues to do this until only a single tag responds.
For Anti-collision algorithm of Hitag S, please check command AC SEQUENCE that is in page 9 of datasheet.

Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.

Best regards,
Kelly
Technical Support
NXP Semiconductor

[abderr]

Hello @KellyLi 

Thank you for your quick response

It's much clearer now

Best regards