When designing boards, one of the things I spend a lot of time checking is if my UART transmit (TX) and receive (RX) lines are the right way round, or switched over. When the design gets to the printed circuit board (PCB) level, it can be nearly impossible to rework. Development of firmware requires it to work; then you have to remember to fix it before re-spinning a new design to correct the issue.
This is where the UART Poka/Yoke comes in
Poka-yoke is a Japanese lean manufacturing technique for “mistake-proofing” processes to aim to achieve zero defects, which would be handy when dealing with TX/RX lines.
I came accross the above image via this Adafruit link, and given how easy it is to impliment I desided to create the schematic and footprint for KiCad so that I can use it in my own UART, RS232, RS485, CAN and other two wire busses where getting them swapped over causes failures.
Poka/Yoke KiCad parts
I have designed a KiCad library and footprints that contain the symbol, and two footprints, one of which uses two 0805 zero-ohm resistors, and one that is made up of two solder jumpers.
They are available to download in this zip file – Poka Yoke UART KiCAD.zip
