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ISO14443 Type B: Maximum NDEF Size

Guru 24520 points
Other Parts Discussed in Thread: RF430CL330H, RF430CL331H, TRF7970A

Hi community member,

Please let me confirm the following question.

[Question]

 Does the NFC protocol define the Maximum NDEF size?

* I think that I should read the NFC project protocol, but please help me.

My customer would like to sent the firmware to their application via RF430CL330H from smart phone. 

At this time, there is a possible that the files size will be over 3KB. So, we would like to introduce some solutions to customer for this.

If you have any question, please let me know.

Best regards,

Kaka

  • for Type 4 tags, the max size allowed is 64kB (as the sub-field for indicating this (inside V-field of the TLV) is two bytes wide)

    for the RF430CL330h, as the SRAM is limited to 3037B (or ~3kB), max size possible to indicate in this field would be 0x0BDD 

    which means per tap, they could send that many bytes over, with the RF430CL330H

    if they want to do FW update or something like that, then they will need to use RF430CL331H or use P2P, with the TRF7970A. (which would be faster) - but understanding their application requirements and cost targets would be something to make sure you understand here. 

  • Hi Josh,

    Thank you for your response.

    Please let  me confirm my understanding.

    [My understanding]

     If my customer want to do F/W update (the file size is over 3KB), they need to use the RF430CL331H or they must tap several times in order to sent it in case of using RF430CL330H.

    Is my understanding correct?

    Also, please let me confirm the following question.

    [Question]

     Can NFC application continue to send the NDEF data without tap(i.e. Keep  put smartphone on application) after finishing to send that data?

       I explain about the usage.

       1. Send the F/W(over 3KB size) to their application from smartphone

       2. First, tap the smartphone to application. ( At this time, send the 3kB data to application)

       3. And send the other F/W data to application without re-tap the smartphone.

     My customer would like to know whether they can do this usage.

    If you have any questions, please let me know.

    Best regards.

    Kaka

  • Kaka - 

    the writing of the tag from a handset will happen all at once. this means that it will not send more data unless tag is sending back request for more time - this is called an S(WTX) request in ISO14443-4 language. The reader will acknowledge this request for more time (according to the time requested by the tag)

    this is how we can use the RF430CL331 to process large messages with one tap, as it is the advanced version of the RF430CL330H. Basically, it has the ability to request more time from the writer (handset in this case), signal (with GPIO) to the MCU to read out current SRAM contents out (thereby clearing it out) and then when timeout elapses the writer will fill SRAM up again, and the process repeats until all data is transferred, inside of one tap action by the user.

    This is still slower than P2P, but a cost effective alternative and one of the main use cases for why we built this device in the first place. (so you could do exactly what you want to do here)

    If the customer can accept slower throughput than what they can realize with P2P, then its perfect fit. The real delay we see here is really on the handset side as NFC Forum currently restricts communications with tags to 106kbps. When 212kbps, 424kbps and 848kbps are allowed, throughput speeds will increase.  

     

     

  • Hi Josh,

    Thank you for your cooperation.

    Please let me confirm the RF430CL331H. 

    Would you please teach the production schedule of RF430CL331H?

    My customer also be interested in this device.

    Best regards.

    Kaka

  • Kaka - 

    RF430CL331H is already in production. Application of it is restricted until mid-next year. If you can send me email at josh.wyatt@ti.com we can discuss what your customer is doing and then see if they can use it now.