Regarding NFC Implementation and FOTA with ST25R3916 and STM32WLE5

[VIGNESH_KUMAR_M]

My organization is currently planning to develop a monitoring unit that will connect with a mobile app via NFC. For this, we have chosen the ST25R3916 NFC module, with the STM32WLE5 series controller as our main MCU. Recently, we started working on the NFC-A configuration for active peer-to-peer communication using the ISO14443A standard.

We are currently encountering issues with lagging during testing and have been unable to find reference sources online for implementation and testing. We have come across a video that demonstrates some testing methods through a GUI, which I will share below. Additionally, we found some source files for the ST25R3916 module, which I will also provide links to. However, the problem is that the complete implementation is in C, while we are looking for a C++ implementation since we are using Mbed OS for development.

We also have a key question: is it possible to implement FOTA (Firmware Over-The-Air) using NFC in passive mode? If so, we would appreciate guidance on the procedure, especially regarding how the SPI communication would work in this context. Additionally, is it possible to switch from passive to active mode when receiving a request from the mobile app? This way, the unit can remain in passive mode to save power (since our application is battery-operated) and then switch to active mode only when necessary to respond to the main controller.

As we are new to NFC, we have several questions, and any information or guidance you can provide would be greatly appreciated.

GUI testing Reference Video : https://www.youtube.com/watch?v=SKy-WrmOImo&t=384s

[Ulysses HERNIOSUS]

Hi,

some pointers to your keywords above:

1. Active P2P is basically disappearing. Phones are not offering APIs for it anymore. I would stay away from it unless you target a fully closed solution of your own two peers.
2. Passive communication goes in both directions. The so-called poller (reader) emits a field and does AM/OOK modulation on its own carrier. The so-called listener (aka PICC, tag, card) will change a load to perform its modulation - this is called load-modulation.

So about transferring data to your device it can be done in passive mode. Actually both directions would be possible. But you sound you would want the listener role on your device side and the poller role on the mobile side.

How large will your Firmware updates be? I am asking as typically NFC is limited to gross 106kbps and net data rate is typically more in the 4KByte/sec.

BR, Ulysses

[VIGNESH_KUMAR_M]

Hi,
Thanks for the reply. The firmware size is currently 134.5KB and may increase to a maximum of 150KB. We are now analyzing the Poller method. Do you have any references for implementing or testing the Poller method?

[Ulysses HERNIOSUS]

Hi,

I am not aware of such reference. It would require an app on the mobile registering for an AID (Application ID). Then the poller can discover the mobile in listen/CE mode and use a SelectApdu to open a comm channel with the app.

The other method could be exercised by changing the pairing demo inside the ST25R NFC lib to replace the weak demoNdefFile with e.g. a JPG - prepended 2 bytes little-endian size of the following JPG. I think also NDEF_SIZE needs to be adapted. 

This way I was once emulating an NDEF tag which will then be read by the Android OS. For a 60KB image it took some 10 secs when using T3T and 13 sec when using T4T.

BR, Ulysses

[Billy OWEN · Accepted solution]

Hi @VIGNESH_KUMAR_M 

This post has been escalated to the ST Online Support Team for additional assistance.  We'll contact you directly.

Regards,

Billy