geekhack
geekhack Community => Keyboards => Topic started by: smw on Wed, 13 August 2025, 09:44:03
-
Sorry if this has been asked before, but search isn't working for me. The diagram for the model F terminal connector (here it is on Admiral Shark's excellent site (https://sharktastica.co.uk/topics/connectors#529XHeader2Soarer)) has pin #3 marked as "PE". Several other keyboards that use a modular connector have a PE pin as well, but I couldn't find any explanation as to what it's for.
-
OK, after a closer look, it appears that PE is the plug/cable shield. Would still like to know what it stands for, though.
-
Hi, Admiral Shark here! I must first disclaim that I am not an electrical engineer, but at most a hobbyist. "PE" stands for "protected earth". At least here in the UK, you may see "earth" and "ground" used synonymously (and the former may even by preferred by IEC/BS standards.)
What a ground/earth is doing is quite context dependent. In their documentation, I have seen IBM refer to such pins as either "PE" or "frame ground". I believe PE is specifically intended for a person's safety context, whereas "frame ground" is more signal integrity. But I guess it functionally does both, and IBM didn't standardise how they refer to it? Also, my use of nomenclature was initially borrowed from KbdBabel (http://www.kbdbabel.org/conn/index.html). They were my inspiration when I started making these diagrams, because I essentially wanted to fill in the blanks.
This talk gives me an idea, though. Perhaps a new section in my Keyboard Connections page for describing pin functions is in order? As such, if anyone else believes I was wrong and has corrections or has anything else to add to what I said, I welcome it. I only want to put out the best information!