How to reliably configure NXP NTag I2C - Pass Through Mode?

Showing results for 
Search instead for 
Did you mean: 

How to reliably configure NXP NTag I2C - Pass Through Mode?

Contributor II

Dear NXP-Forum,

I'm trying to configure the pass through mode with my NXP NTag I2C. I'm trying to send dynamically data from I2C to my smart phone via NFC. Here are my configuration-steps:

1. I've put FD_OFF and FD_ON to 11b from the Config Register via Phone.

2. While being connected via NFC, I've changed the NC_REG to 7B via I2C:

Bit 6 = Pthru_on

Bit 54   = FD_ON 11b

Bit 32 = FD_ON 11b

Bit 0 =  0 Direction from I2C to RF.

3. Afterwards I try to write SRAM, which usually doesn't work. Also the NTAG sometimes thinks it's password protected, even though I've neither entered one, nor activated it. Putting in any passowrd displayed (Sun, Moon and so on) doesn't open up the NTAG. Only after disconnecting Arduiono from my PC disables the password-protection.

Once I also managed to almost complete a pass through cylce, but I somehow couldn't go any further from there. I.e. how I exactly read/write Sram via phone or how either knows, that the data can be picked  up. (See picture)

I know I'm asking a lot in this forum lately and I really hope I don't bother anyone with that, but you guys have been a great help for me, trying to understand how everything works. 

Thank you in advance.

Best regards


0 Kudos
1 Reply

NXP Employee
NXP Employee

Hi Norman,


Hope you are doing well. I am aware that there are two threads with the same question, so to facilitate communication I will continue the support in these other thread:


Best Regards,


0 Kudos