topic NTAG I2C Plus giving NACK over i2c in NFC

NTAG I2C Plus giving NACK over i2c

tarunpanchal — Wed, 30 Aug 2017 10:21:23 GMT

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?

Re: NTAG I2C Plus giving NACK over i2c

kaibuechler — Mon, 04 Sep 2017 17:48:10 GMT

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.

Re: NTAG I2C Plus giving NACK over i2c

Kan_Li — Wed, 06 Sep 2017 07:32:31 GMT

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

Have a great day,
Kan

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Re: NTAG I2C Plus giving NACK over i2c

kaibuechler — Sun, 10 Sep 2017 15:46:17 GMT

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).

Re: NTAG I2C Plus giving NACK over i2c

kaibuechler — Sun, 10 Sep 2017 16:23:18 GMT

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.