NFC type 4 Write

[Arepa]

Hi all,

I am trying to study the NFC type 4 write and how use the values received.

I cant find where can I see the data I am receiving when I write to a nRF52 tag using a smartphone (in code), I just can see it reading back the tag using the a smartpone.

Where can I see the values I wrote?

I am using the SDK13 and nRF52.

Thanks

[Jørgen Holmefjord]

Hi,

When the NDEF buffer is updated (written), you will get a NFC_T4T_EVENT_NDEF_UPDATED event in nfc_callback. Typically, this will happen two times, as described in this answer. The data will be available in the NDEF message buffer given to the function nfc_t4t_ndef_rwpayload_set, which in the writable NDEF message example corresponds to m_ndef_msg_buf. The first two bytes of the buffer, the NLEN field, contains the length of the data.

Best regards,

Jørgen

[Arepa]

Hi Jørgen, I checked it, now I am receiving the data I wrote, but always on the first write I received corrupt data (always the same message possibly the last message default data on the buffer?)

update: I fixed it reading the m_ndef_msg_buf when it match with the expected data in NLEN field

[Jørgen Holmefjord]

Yes, the message buffer will be filled with old/garbage data. You need to use the NLEN field to get the valid data from buffer.