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DLP-RFID2 can't write more than 30 bytes in the NDEF payload

devWarrior
Intellectual 330 points
Other Parts Discussed in Thread: RF430CL330H, TRF7970A, RF430CL331H

I am having trouble writing to a RF430CL330H type 4 tag from the DLP-RFID2 writer. Here is my original post:

e2e.ti.com/support/wireless_connectivity/nfc_rfid/f/667/t/509685

I've attached 2 logic analyzer captures using the Salae logic analyzer. After a lot of testing, I came to the conclusion that the DLP_RFID2 can write 30 bytes and under successfully in the NDEF payload. If I want to write 31 bytes and above, the DLP-RFID2 won't reply. Is this a firmware bug? Is there any way around this? I've contacted DLP Design directly and they said to post here to get help.

ps - I know the problem is not the RF430CL330H, because it works with the DLP7970ABP with 50+ bytes, and with NDEF messages less than 30 bytes on the RFID2

Salae Captures.zip

  • 0
    TI__Guru*** 131490 points
    Hi dev,

    Perhaps we at TI will need to reach out to DLP Design about this because the firmware on the DLP-RFID2 is not our own and we have no control over what it is doing or how it is configured at all. The firmware and how that DLP-RFID2 part behaves is defined by DLP Design, not Texas Instruments. I doubt it is a bug, it is likely done by design.

    We know it definitely isn't an issue with the RF430CL330H as well. The issue lies in the firmware which has been loaded into the DLP-RFID2 module and nothing else.
  • 0 in reply to Ralph Jacobi
    Intellectual 330 points

    Could you please? I emailed DLP and this is the response I got. I don't know what to do. I've even tried several RFID2 modules we have with the same results.

  • 0 in reply to devWarrior
    TI__Guru*** 131490 points
    Hi dev,

    After discussions, we have concluded that the 30 bytes at a time is the limitation of the firmware which is loaded into the DLP-RFID2 module. The only workaround to this limit is to send out multiple reads of 30 bytes.

    So basically there are two options for you right now I think
    1) If you want to use the FCC certified module then use separate transaction to get the data
    2) If you want to go through your own FCC cert, then you can layout a custom board based on the TRF7970A schematics online and have the full abilities of the TRF7970A available to use including being able to send/receive 255 bytes per packet.
  • 0 in reply to Ralph Jacobi
    Intellectual 330 points
    Thank you so much for verifying that. It would be too much work to go through the FCC and design our own board. I will use multiple transactions.
  • 0 in reply to Ralph Jacobi
    Intellectual 330 points
    I've been struggling to get this DLP-RFID2 sending 2 simultaneous writes to the RF430CL330H tag. Looking at this question:

    e2e.ti.com/.../1301866

    it looks like I won't be able to do 2 writes unless I remove the tag from the RFID field. Is there any way I could modify the firmware on the DLP-RFID2 to write more than 30 bytes, or is there another type 4 tag similar to the RF430CL330H that can receive multiple writes without having to remove it from the RFID field?
  • 0 in reply to devWarrior
    TI__Guru*** 131490 points
    Hi dev,

    As Alex mentioned in that post, the RF430CL331H would be a possible chip you can use to avoid that issue. It has been released since that post was made. It's a Type 4B Tag like the 330H is.

    I don't think it is possible to modify the DLP-RFID2 firmware, but if it is, that is something DLP Design would need to help with as I don't know how one would access a JTAG or SBW for programming the module.