NTAG I2C Plus giving NACK over i2c

[tarunpanchal]

I am working on  NTAG I2C. plus 2k version

I  Could read/ write to the NFC chip through the host microcontroller and a NFC device.

Now all of sudden the I can neither read nor write into the NFC chip through I2C from the host MCU, but I can read/ write NDEF mesages through my mobile phone (NFC device). I can also read registers using the NXP Android app.

I check the I2C pin, everything is correct.

Can someone please tell me whats going on here?

[kaibuechler]

I think I found the Problem. It seems like the reset button of the ntag demo app is Setting the slave address of the tag to 0. 

[Kan_Li]

Can the I2C host access the register in the tag? for example, the session register.

Have a great day,
Kan

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[kaibuechler]

Hello,

no I cannot access seassion or config registers. I'm geting a NACK after sending the NTAG address and a 0 for writing.

I can read the seassion and config registers over nfc, but writing the config registers fails (with the nxp nfc demo app).

Like I've said before, a new chip works for a while, but they'll  start to act weird sooner or later (all 4 chips usesd are from the same reel). 

[kaibuechler]

Hey, 

I'm having the exact same problem! I already killed 4 of these tags in a row. Reading worked fine for a few weeks (I was developing other stuff meanwhile but a reading of the config Register after every reset was implemented), than I started to write to the tag (over I2C) and the chip died after a few resets. With the Android app you can still connect, but writing to the config register stopped working in most of the cases.

What I did so far:

I checked the i2c bus with my scope - looks good, no noise, no Spikes.

I checked the supply voltag, steady at 3.3V with Vpp of 30mV

May I ask which mcu you are using? For me it is a EFM8B2.