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MERSI
Associate III
March 5, 2025
Solved

Advice on Using NFC for Sensor Identification in a Multi-Sensor System (STM32)

  • March 5, 2025
  • 2 replies
  • 696 views

Hi everyone,

I'm working on a product that involves multiple sensors connected to a main system. Up to six sensors can be attached (see image). The overall diameter of the system (as shown in the image) is approximately 20cm. I want to use NFC tags on each sensor to identify the type of sensor (including ID and other details) when plugged into the system.

The sensors are eventually connected to another system via cables. The sensors only output current (and are supplied with voltage) – so, two wires ( + - ). The identification of the sensors (reading the NFC tags) will then be transmitted from my system to the main system.

I've come up with two antenna concepts (see image) for this purpose:

  • A single large antenna for all sensors
  • Individual antennas for each sensor

Which approach would work better? Does anyone have experience with this? I'm particularly interested in how the NFC performance would differ between these two antenna configurations.

In the version with multiple antennas, I was thinking of using a multiplexer so that only one NFC reader is needed. For this, I’ve considered using either a PIN diode circuit (do these work well for NFC systems?) or an RF switch IC. Have any of you used these or can recommend one over the other (or maybe a different technique)?

The NFC tags are mainly only read once, during system power-up, to identify the attached sensors.

Additionally, could anyone recommend a development board that would be suitable for testing out these ideas? I’m looking for something that can help prototype the NFC functionality and sensor connections quickly.

One additional question: Will the antennas interfere with or disturb the sensors in any way, even if they're only used once during system startup? For example, could they cause increased susceptibility to external disturbances or other types of interference? Are there any tricks or techniques to mitigate or reduce these potential effects?

I appreciate any input or advice you can share.

Thank you in advance!

Best regards

 

nfc_antennas_concept.png

 

 

This topic has been closed for replies.
Best answer by Ulysses HERNIOSUS

Hi,

In your six antennas configuration the antennas will most likely also read neighboring tags. Especially for those at 2,4,8 and 10 o'clock positions. 

BR, Ulysses

2 replies

Andrew Neil
Andrew Neil
Super User
March 5, 2025
@MERSI wrote:

I want to use NFC tags on each sensor to identify the type of sensor (including ID and other details) when plugged into the system.

Why NFC?

If they are plugged-in, wouldn't it be easier to obtain this information over the "plug" interface ?

Some more background on the setup would help ...

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
    M
    MERSIAuthor
    Associate III
    March 5, 2025

    The sensors are eventually connected to another system via cables - there is no electrical connection to my system. They simply output current (and are supplied with voltage by the other system) – so, two wires ( + - ). The identification of the sensors (reading the NFC tags) will then be transmitted from my system to the main system.

      Ulysses HERNIOSUS
      Ulysses HERNIOSUSBest answer
      Technical Moderator
      March 5, 2025

      Hi,

      In your six antennas configuration the antennas will most likely also read neighboring tags. Especially for those at 2,4,8 and 10 o'clock positions. 

      BR, Ulysses

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