I’m starting to design a PCB to host a B524 SoM and would need to attach it to an off the shelf wiegand RFID\NFC reader.
Since I know that the B-SoM is 3.3V logic and Wiegand is 5V logic I have added a voltage level shifter (TXS0102) and capacitors + resistor as recommended by the datasheet of the TXS0102.
I also went and read this nice blog post and took some tips on the design from there (added current limiting resistors, optional pull-up resistors and ESD protection diodes).
My question, as this is a device that will be handled in the field by someone wiring it that might not be so “delicate”, is how should I protect this interface so that in case of an error the the Wiegand reader would not fry the B-SoM?
Here’s the current design, the Nets D0 & D1 connect to the B-SoM D0 & D1 respectively.