PN7150 does not communicate with tag

[co23]

Hello,

I am using the PN7150 in poll mode with FrameRF Interface using ISO15693 protocol.

The tag I am using is ICODE SLIX HC (SLS2102).

The PN7150 is running on a self developed PCB and is controlled with a STM32F4xx uC on another PCB.

First it ran without problems, but within one day, the PN7150 stopped to communicate with the tag.

Everything runs fine, the initialization, and the start of the discovery signal. (The discovery signal can be seen with the scope and a little antenna.)

When I hold the tag over the transmission antenna, nothing is changeing, the discovery signal stays the same, also  no change on the IRQ pin can be registered.

When I use a exact copy of the PCB running the PN7150 and the same firmware. It runs without problems.

So I think it is a hardware defect, on the PN7150 but I want to know, what is the possible cause of this defect, to avoid further failures. Does anyone had the same issue?

Best Regards

Heinz

[co23]

Hello Ivan,

i have doublechecked with a duplicate of the custom board(with the exact same antenna and matching circuit), the tag is not damaged, other tags are also not working. I am really confused, because the board worked at first very well and suddendly gave me this failure, I think if the design of the antenna is really the issue, then none of the boards would work( I have five of them). But that is not the fact. I added two oscillograms from the discovery signal, one from the working board an one from the failing board. Meassured with a small coil above the antenna.

Working PCB

Not working PCB

I am now going to check my antenna design.

Regards

Heinz

[IvanRuiz]

Hello,

From my point of view, having being presented the fact that you can start the polling mode in the PN7150 custom board and after you have confirmed it with the oscilloscope. It is most likely the antenna which is not design correctly and is intermittent. There could also be the possibility that the tag is damaged, please try with another one to confirm or you can also read the tag with TagInfo app by NXP for mobiles. 

Please refer to the antenna design and matching guide for PN7150:

PN7150|High Performance Plug'n Play NFC for OS|NXP 

I hope this helps!

Regards,

Ivan.