Only receiving 0xFF from NTAG 5 Link when reading registers over i2c

[Lukas5]

Hello,

I am trying to set up my NTAG 5 Link. I want to set the ED-pin to change levels when an HF-field is detected. I am doing this like I read in the datasheet, I am writing the Value 0x01h to the register with the address 0x10A8h. When I check the ED-Pin with the 3.3 V connected to the Tag, the ED-Pin is at a level of 2,92 V.  The Problem is, when I try to put my phone on the tag, the level of the pin is not changing.

So I tried to read the register Value to check if it was written correctly. Now the problem: Whatever register I am trying to read on my device via i2c, I am always getting the Value “0xFF”. Why is that happening? Did I do anything wrong?

Would be really happy if someone could help me.

Kind Regards

Lukas

[Lukas5]

Hello Ricardo,

thanks for your answer. Yes, I have checked the Application Note. I tried setting the ED register to the wanted Value of 01h, but the ED-Pin is not changing from HIGH to LOW when a NFC-Field is next to the tag. Because of that, I tried to read the register, to check if it contains the right value. When I do this, I am only getting an 0xFF back over I2C. This happened when I tried to read other registers too, although the Value can't be 0xFF, I think.

Unfortunately I don't have any I2C logs right now, but I am getting the ACKS from the NTAG to my master when reading and writing, so it seems like the communication is working right, only the Value is weird.

Regards

Lukas

[Ricardo_Zamora]

Hello Lukas,

Could you please try getting some I2C logs? Without some logs, it would be hard to identify this behavior.

Also, can you read these registers by NFC interface?

Regards,

Ricardo

[Lukas5]

Hello Ricardo,

sorry for the late answer. I got some I2C logs, as you can see in the attachment.

In the first picture is the logic level of the I2C traffic and in the second picture you can find the data in text.

I tried reading the register with the address “10A8”. After transmitting the request, I only receive an “FF”, as I have explained before. Do you have any idea what I am doing wrong?

Thank you for your help!

Regards,

Lukas

[Ricardo_Zamora]

Hello Lukas,

Hope you are doing well. Could you please check section 5.1 of this Application Note? NTAG 5 - Use of PWM, GPIO and event detection

Do you have a log of the I2C communication?

Regards,

Ricardo