No ACK signal issue of NT3H1201 I2C-I/F with the I2C address at 0x55 as the default.

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No ACK signal issue of NT3H1201 I2C-I/F with the I2C address at 0x55 as the default.

Contributor I

Dear all,


We are working for the I2C-I/F of NT3H1201 but have not received an ACK signal with the I2C address at 0x55 from SDA of the NT3H1201. Please see the page 3 of the attached file.


When we did put 0x00 on the I2C address field, the NT3H1201 sent an ACK signal back to the I2C master device. So, we suppose that our AC timing implementation must be correct. Please see the page 6 of the attached file.


After setting the I2C address field to 0x00, we did read the user memory space from an HF RFID R/W and saw the original user memory data but could not find the write data on the user memory of the NT3H1201.


As you know well, 0x00 is called "General Call Address" in the I2C specs and seems the broadcast address. So, we will not be able to use the General Call Address at 0x00 for the general write/read operations.


Could you please help us to fix the above no ACK signal issue in NT3H1201?


Thanks and regards.

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1 Reply

NXP Employee
NXP Employee


First of all, let me apologize for the late response, we are currently under a great load of work and there is delay on our responses.


I made some test with NTAG I2C, and its correct what you did. You can change the I2C address.


I read the memory from the device, with the original 0x55 address, and I received values from the 0x00 memory address.


Address 0x55.png


Then I changed the I2C address to 0x00, same as you. And again read the same memory register, and I received the same values.

Address 0x00.png


The issue could be when you write to the User Memory. Please make sure the host it is doing correctly.


You can try using the Peek and Poke tool if desired to make sure that you are writing the correct address.

Best Regards,


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