NTAG I²C - Unable to modify data in user memory space

[helmitoncunhajr]

Hello folks!
I'm having with a NTAG I²C 1k, using its I²C interface to communicate with a Genuino Uno. I'm able to read data without trouble, but for some reason I cant modify anything on the user memory space (01b to 37b). The data seems fine in my logic analyzer, I receive every ACK as I'm supposed to and the data in the bus follows the READ and WRITE operations protocol on the datasheet. But when I try to read them, I always read zeros. My reading operation shouldn't be the problem, as I'm able to read properly other sections of the memory such as 00b (that contains addr, serial number, cc and static locks). Actually I was even able to change the addr on one of the tags, but even then I wasn't able to modify the user memory space. I've also checked the static lock bytes and made sure they're set to 0 just in case.

What am I missing here? Is there something, maybe a configuration step I'm missing?
I have attached prints of my logic analyzer just in case.

Thank you for your time!

[Kan_Li · Accepted solution]

Hi Helmiton,

Please use 16 bytes for writing operation.

Wish it helps.

Have a great day,
Kan Li
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[helmitoncunhajr]

Thank you so much! It worked like a charm! I was sure it would be something with the I²C locking, I had no idea that I needed to write the whole block in order to properly modify it.