Same Board, Same Code — Issue Seen Only After Replacing NFC Module (OM27160A1HN)

[Niranjan123]

Hello everyone,

I am interfacing the OM27160A1HN NFC module with the OM29110RPI-B Raspberry Pi interface board.

Setup Clarification (Important)

• Same OM29110RPI-B interface board

• Same Raspberry Pi

• Same firmware, binary, and configuration

• Only the NFC module (OM27160A1HN) is replaced

Observed Behavior

• NFC Module #1 (Working):
  The application works correctly and I get the expected NFC output.

• NFC Module #2 (Not Working):
  With the same board and same code, the NFC functionality does not work as expected.

Since the exact same hardware platform and software work with one NFC module, this strongly suggests that:

• The code is correct

• The interface board is fine

• The issue may be related to the specific NFC module, its electrical behavior, or tolerances

What I Have Checked

• Same wiring and connections

• Same initialization and reset sequence

• No software changes between tests

Additional Debug Data

• I have attached:

  • Screenshots of working vs non-working runs

Questions to the Community

1. Are there any known module-to-module variations, errata, or sensitivity issues with OM27160A1HN?

2. Could this be related to:

   • Reset / VEN timing

   • IRQ behavior differences

   • Internal oscillator / RF startup differences

3. Are there any recommended electrical checks or minimum signal requirements that should be verified when swapping NFC modules?

4. Has anyone seen a similar case where one OM27160A1HN works and another does not on the same board?

Image 1: Not Working Module

The top waveform is the IRQ and the below is the clock.

IRQ is asserted by the host, but no response is observed from the NFC module. No clock activity is generated after IRQ, indicating the module is not responding.

Image 2: Working NFC Module

The top waveform is the IRQ and the below is the clock.

IRQ is asserted by the host, and the NFC module responds correctly. Clock activity is observed on the bus after IRQ, indicating normal operation.

Any guidance on what parameters or signals I should focus on next would be very helpful.

Thank you for your support.

regards,
Niranjan

[Tomas_Parizek]

Hello @Niranjan123 

Thanks for the provided data! 

Yes, it really looks that something is wrong with the board. 

Did the board have these symptoms out of the box or something happened during debugging ? 

Where did you buy this board ? If from nxp.com, you can go for Returns and Warranty.

BR

Tomas 

[Niranjan123]

Additional observation:
In the not working board, I could observe that the SDA line stays low. This doesn't seem to be the right default state. could this indicate something?? 

[Tomas_Parizek]

Hello @Niranjan123 , 

Do the both boards use the same configuration file (libnfc-nxp.conf) ?

Can you double check that, please? 

I see that the IRQ and Clock signals have a different polarity on the "Non working" board. 

What if you use the NFC Factory Test application ? 

https://community.nxp.com/t5/NFC-Knowledge-Base/PN7160-Extended-NFC-Factory-Test-Application-for-Lin...

BR

Tomas 

[Niranjan123]

Hi, @Tomas_Parizek 

Yes, I double-checked the configuration and can confirm that both setups are using the same libnfc-nxp.conf file, with no differences in content or path.

As suggested, I also tested using the PN7160 Extended NFC Factory Test Application.

Observations from Factory Test Application

• Working NFC module:
  The factory test application initializes successfully and proceeds beyond reset. The PN7160 is detected, and the application displays the test menu as expected.

  

• Non-working NFC module:
  The factory test application does not progress beyond the reset stage. The output stops immediately after reset, and the application does not reach the test selection menu.

  

  Since:

  • The same interface board is used

  • The same configuration file is used

  • The same software stack and factory test application are used

           and only the OM27160A1HN NFC module is replaced.
  
  

  Thank you for your guidance.

  Best regards,
  Niranjan