Which method would be better to transfer data to/from the ST25 - FTM (mailbox) or NDEF ?

[NDvas.3]

Our hardware, based on the ST25DV, needs to communicate with a smart phone and send/receive short bursts of data. I have the FTM already working but we are also looking to use the NDEF protocol so we would be compatible with the iOS/Android standards.

I will be glad to hear your professional opinion on this since this is our first NFC project.

Thank you,

Nir.

[JL. Lebon]

Hello Nir,

If you send/receive short bursts of data, the FTM is clearly the best way to go.

The main difference between FTM and NDEF is that FTM does not use the EEPROM memory, when NDEF does. This has several advantages:

• write speed (EEPROM is 5ms for programming a block, whereas FTM has no programming time)
• cycling endurance: no cycling when using FTM, whereas EEPROM has limited cycling life.

Another advantage is that FTM does not requires the overhead of NDEF messages.

The drawback of FTM is that it is proprietary. So you need a dedicated application on your smartphone to have it working.

Using NDEF, you are "standard". But what iOS and Android can do in "standard" with NDEF is quite limited. If you want to do short send/receive bursts of data with NDEF, you will quickly be limited.

NFC Forum defined a protocol called TNEP on top of NDEF, that is using NDEF messages to do bidirectional exchange of data in a similar way as FTM. But it is currently not natively supported by iOS and Android, so the standard aspect of this is very limited.

Best regards.

[NDvas.3]

Hey J.L.

Thank you so much. One last question: Does NFC based payments like Apple Pay etc also use the NDEF protocol or is it something else?

Nir

[Ulysses HERNIOSUS]

Hello Nir,

the question is quite unrelated to the original request. If you want to have details please open a new thread. In short: Payment in general is based on EMVCo which uses smartcard APDUs (ISO7816-4) to perform its job. NDEF is not a protocol but a data format to denote hyperlinks, etc. On an NFC Forum T4T APDUs are used to read and write NDEF content.

BR, Ulysses

[NDvas.3]

Hey JL,

Is it possible, using NDEF, to do both send and receive data using a single NFC exchange or will I need to ask the user to remove the smart phone from our device after the write and then bring it back in range to perform the read?

Nir.

[NDvas.3]

Hey JL,

Would really love to hear your answer on this since this will help me decide if we will be using the FTM for this project or NDEF.

Thank you,

Nir

[JL. Lebon · Accepted solution]

Hello Nir,

"Is it possible, using NDEF, to do both send and receive data using a single NFC exchange or will I need to ask the user to remove the smart phone from our device after the write and then bring it back in range to perform the read?"

You don't need to remove the smartphone from the device after write. This can all be done in the same NFC session.

The difficult point using NDEF for this kind of exchange is to correctly synchronize both sides. The MCU on the NFC side needs to know when the smartphone has finished to write the NDEF message before starting to write its own new NDEF message. One the other side, the smartphone needs also to know when the new NDEF message is ready to be read.

But in any case, no need to remove and bring back the smartphone.

Best regards.