I'm working with a PN7160 devkit, the OM27160A1HN (I2C version), connected to a Karo QS93 which features an i.mx93 processor.
The issue I'm encountering has to do with the two voltage inputs of the devkit (screenshot from the devkit user manual):
It can be seen that both VDD(PAD) and VDD(UP)/VBAT are supposed to work with a 3.3V input. But the issue I'm running into, is that the devkit can't detect a tag, when using this 3.3V input voltage. ONLY when providing VDD(UP)/VBAT with 5V from the Karo QS93, the devkit will actually detect the tag and can successfully read its data. When providing this pin with 3.3V the tag CAN NOT be detected.
Regarding the software: I use the libnfc-nci library and the provided nfcDemoApp to verify the devkit. Link to the library:
https://github.com/NXPNFCLinux/linux_libnfc-nci
I run the demoApp with the 'poll' argument, and the tag is only detected and read out successfully, when using 5v for VDD(UP)/VBAT. With 3.3V, nothing happens, whatever I try. The demoAPP is just stuck on "waiting for tag" in that case.
I've read through all the related documentation and have not been able to find any remarks that address this issue. So for now I'm a bit stuck on this, any help would be greatly appreciated!
There is a very similar issue described in AN13892. It could happen that PN7160 can not generate an RF field due to bad power supply on VUP/TVDD or a bad power configuration. Typically happens once 3.3V as the VUP has been used.
https://www.nxp.com/docs/en/application-note/AN13892.pdf -> 9 TXLDO check
Can you try to disable the TXLDO check?
Regards
Daniel