G84-4100PPAUS: parallel port to USB?

[Dreamkey]

Hello everyone,

I just salvaged a G84-4100PPAUS, which is really good because I was thinking to buy a keyboard for my tablet - I travel a lot by train, I think it can be useful to write long emails.

The problem... it uses a parallel port:


I opened it to check what I can do, here is the chip:


You can see 5 wires; I opened the plug, so the two black wires are ground, green wire is auto feed (pin #14), yellow and white are data bit 1 (pin #3) and data bit 2 (pin #4).
The parallel port seems to come from the manufacturer, but all the others G84-4100 keyboards I saw are using PS2 or USB.
Do you think it's possible to rewire it so I can have a more modern connector? I was pondering to mod with a bluetooth module (if such things exist) because I'm not sure my tablet is OTG.

Thank you

[Dreamkey]

Little update: I was able to find here the keyboard's pinout.
So I rewired it on a PS2 cable, it worked perfectly
By the way, I said "parallel port" because of the DB25, but with only 4 wires inside, it was simply a DB25.
Next step, I tried a passive USB converter, obviously it didn't work, but with an USB converter I was able to use it.

Now I would like to know, it was a cheap USB converter like this one ("13ba:0018 PCPlay Barcode PCP-BCG4209" from lsusb), and for the few minutes I played with it, it seems to work well.
A lot of people recommend the "blue cube" (UA270), saying those cheap adapters don't work correctly; I live in EU and can't find blue cubes for a correct price, plus I already have on hand my converter, so I am missing something?

[suicidal_orange]

Great news!

As for converters if it works it works - give it a thorough test ( olots of typing, boot plugged in, hotplug, sleep/wake, bios/bootloader?) and if it it's all good be happy you saved yourself some money.  No-one will recommend you buy a cheap one as it may not work, but if they were completely useless they wouldn't make them

[Dreamkey]

Thanks for your answer.
I did some extensive testing: no problems for coldplug/hotplug, sleep, BIOS. But with gummiboot (now systemd-boot), I was able to go down once inside the menu, then it was stuck (the keyboard, no problem with my laptop keyboard).
Also I tried with a French keyboard, it has one additional key like the UK keyboard. This additional key works well, but for some reason KP_Divide doesn't. I can't tell if it's my keyboard or the adapter, while it works correctly on the G84.

Then I tried to clean it by removing all the keys, but I realised some tabs were bent during the process, so I stopped.

Also I received my OTG cable, it works well with my tablet.
I will post some pics of the USB conversion during the week

[Dreamkey]

And here is the result!

All the magic is inside the epoxy, there is not a lot to see. Each square is 5mm, as you can see it's quite small.

The back helps for the pinout:


I desoldered the existing cable, removed the zip tie and used one of its hole to pass the USB cable (another salvage from a mouse), it should help if it get pulled on.


Pretty happy with the result, I get some black looks in the train but it's really useful

[suicidal_orange]

Ooh an internal mod - very nice!

I would have thought the train is one place keyboard noise would not be problem...