NT3H1201: NDEF data can be stored from in the middle of user memory?

[norihiromichiga]

Hi,

Please advise me if my usage can be allowed by NT3H1201 device.

I want to reserve some memory area (around 300 byte) of user memory,

So I write NDEF to user memory in  the middle of user memory space like below.

----- User memory (start page)

0x00 0x00 0x00 0x00  // For reserve purpose

   :

0x00 0x00 0x00 0x00  // For reserve purpose

(Actual NDEF data is stored from here)

   :

   :

----- User memory (end page)

With this usage, I noticed that some Android 5.0 or later terminals couldn't read NDEF data.

Do you think that my usage is possible? 

Thanks,

Norihiro Michigami

[norihiromichiga]

Hello Jorge-san,

Thank you for your comment. I understand Android may expect that valid NDEF records at the begining of block.

After that, we tried to set "Empty record" at the begining of NDEF message as RESERVED area of memory, instead of using NULL TLV. But it doen't work (Android seems to not be able to detect it as valid NDEF message)

Thanks,

Norihiro Michigami
AVNET

[norihiromichiga]

Hello,

Anyone can help me? 

Simply, my question is that whether Android can read NDEF message after multiple NULL TLV(0x00).

NFC forum Type2 spec seems to ask a NFC reader to skip or ignore such NULL TLV and read the next byte.

Thanks,

Norihiro Michigami

[Jorge_Gonzalez · Accepted solution]

Hello Norihiro:

I tried your use case of storing an NDEF text record at the middle of an NTAG I2C chip and then reading the tag. I tried with 2 android phones and both interpreted the tag as EMPTY.

According to the NFC Forum T2T specification, the NULL TLVs shall be ignored, but it does not imply that the NFC device should scan the whole memory looking for NDEF records.

The usual case is to store NDEF records at the start of user memory space, so I guess that is what Android devices expect.

That storage must be possible, but you would need to develop a custom Android app. For this NXP has the MIFARE SDK framework. See more information in the next links:

https://www.mifare.net/en/products/tools/mifare-sdk/

http://www.nxp.com/wcm_documents/products/related/customer-training/mifare_sdk_webinar_slides.pdf

I hope this helps.

Best Regards!,
Jorge Gonzalez

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