the write speed is too slow when writing date into Half-duplex 256 bytes dedicated buffer

[ivantan]

hello sir

       I am using the fast transmission mode of the nfc chip ST25DV04KC to transmit picture data. The NFC chip is used with the MCU of  STM32G071G8U6. When I write the 25KB picture data through the mobile APP into the NFC cache, I find that the entire writing time takes about 11 seconds. Please tell me know, Is the transmission and writing time normal? If not, what is the error? If normal, is there any other chip or solution that can replace it? I need to control the entire time within 4 seconds

Thank you.

[JL. Lebon]

Hello, 

The 11s time to transfer seems normal. It may be possible to optimized it a little bit to gain 1 or 2 seconds but not more.
Please take into consideration that ISO15693 data-rate (from reader to tag) is 26kb/s. You have to transfer 25000*8 bits. So even if we don't consider protocol overhead, at 26kb/s, the minimum theorical time would be 25000*8/26000=7.7s.
If you want to transfer data from the MCU to the reader, then you have the possibility to use the Fast data-rate, which is 53kb/s. In that case, you can expect faster transfer time (not divided by 2 due to protocol overhead, but close). But this only work in this direction, not from reader to MCU, and it is not supported by smartphones, only by RF readers (like ST25R3916).

Best regards.

[ivantan]

Hello

thanks for you kind reply.

The writing time of 11 seconds is the actual measured time, even if it is reduced to the theoretical time of 7.7 seconds, it is a bit long. If I want to shorten this time to less than 4 seconds, does ST have any other FTM solutions that it can provide?

[Ulysses HERNIOSUS]

Hi ivantan,

theoretically you could use one of our reader chips supporting card emulation. In card emulation mode you can use NFC-A 106kbps and NFC-F 212kbps and 424kbps. 

Candidates could be ST25R3916B / ST25R3918 and others. We don't have a ready-made bi-directional demo implemented but such could be done. With the pairing demo (part of STSW-ST25R-LIB) you can emulate an NFC Forum T3T or T4T and look at the achievable net data rate. 

Previous experience with two ST25R3916 tells gross 30KByte/sec (@ net 424kbps) to be achievable. Smartphones are likely slower (more internal transfer over low speed i2c busses, phones not optimized for NFC throughput, etc.)

BR, Ulysses

[JL. Lebon]

Hello, 

Unfortunately, ST has currently no FTM solution to reach your 4s target. Sorry for this.

Best regards.