FAQs
cancel
Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for 
Search instead for 
Did you mean: 

Writing to 20 NFC Stickers: Can X-NUCLEO-NFC12A1 Do Antenna Multiplexing

pnuno_2002
Associate

‎2025-11-03 4:27 AM

 

Hi,

I need to write the same kind of NDEF data to ~20 different NFC stickers placed on a panel. The idea is to have ~20 small antennas, select one at a time, and write to the sticker sitting above that antenna.

Questions:

  • Can I do this with X-NUCLEO-NFC12A1 + STM32 by multiplexing the RF path (switches/decoder → select 1-of-20 antennas)?

  • Any recommended switch/multiplexer parts or reference designs for 13.56 MHz?

  • What are the practical limits on antenna count and cable/trace length when switching like this?

  • Do I need individual tuning (matching caps) per antenna position?

  • Is there a better Nucleo shield for this use-case (e.g., higher RF drive) or is NFC12A1 enough?

Goal: operator chooses pad 1…20, we write an NDEF, verify, then move to the next pad.

Kindly advise—example schematics/app notes or code pointers would be great.

Rgds,
Rp

#stm32 #nfc #x-nucleo-nfc12a1 #antenna #multiplexing #ndef

0 Kudos
1 REPLY 1
Travis Palmer
ST Employee

‎2025-11-05 1:11 AM

Hi pnuno_2002,

 

please have a look at AN6121.

There are also some interesting posts regarding this topic.

Please have a look at this post.

  • Can I do this with X-NUCLEO-NFC12A1 + STM32 by multiplexing the RF path (switches/decoder → select 1-of-20 antennas)?

    • Yes, please take a look at AN6121 as a reference. 

  • Any recommended switch/multiplexer parts or reference designs for 13.56 MHz?

    • There are very little multiplexer ICs available for NFC/RF  applications. (either too low voltage or too high dcr). This is why we came up with AN6121.

  • What are the practical limits on antenna count and cable/trace length when switching like this?

    • At the end with every antenna and every cm of trace, additional parasitic capacitance is being added. It is hard to predict a maximum number of antennas. 

  • Do I need individual tuning (matching caps) per antenna position?

    • Yes, due to the parasitic capacitances and different environmental effects it might be required to tune each antenna individually.

  • Is there a better Nucleo shield for this use-case (e.g., higher RF drive) or is NFC12A1 enough?

    • At the end you will need to design one PCB implementing the NFC IC and multiplexer. The antennas can either be dedicated or part of this PCB. A dedicated antenna (twisted pair cable or coaxial cable) makes it hard to predict parasitic components. Please have a look at AN5592.

Please let us know, if you have additional quesitons.

 

br Travis

0 Kudos
Top