PS/2 to USB Adapter


14 posts
by gardrek » Sun Feb 26, 2012 4:42 pm
Hi, everybody! I was wondering if it is possible to use a PS/2 to USB adapter (such as the one shown in the image below) with the Pi. A quick Googling tells me that this is probably not a converter, but just a passive adapter. I read the FAQ, searched the wiki and the forums, but couldn't find anyone talking about this. Sorry if this is one of those "We won't know until it's out" things. Thanks for all the help.

PS/2 to USB Adapter
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by grumpyoldgit » Sun Feb 26, 2012 4:57 pm
I have quite a few old PS2 mice and keyboards and was thinking of using them with an adapter as I am trying to do the whole Pi thing with the absolute minimal cost. The problem appears to be that they only work with devices that are usb compatible. There are a number for sale on Amazon and they get really bad reviews. Basically, they don't seem to work with some devices and often particular keys don't work. On that basis I have decided to invest in a mouse and keyboard from Tesco, Asda, Wilkinsons or similar; the total cost of which will be about £10.
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by drgeoff » Sun Feb 26, 2012 5:17 pm
The adaptors that come with mice and keyboards generally are just passive.  The mouse or keyboard is dual mode and switches automatically depending on the presence of the adaptor.

However, I cannot see how that trick could work to put two separate devices into one USB plug.  So I think the one that gardrek shows must be an active device.

I have a similar device that I found in the skip during a tidy up at work some years ago.  I've never tried it.  Must dig it out some day and give it a go.
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by davehiggins21 » Sun Feb 26, 2012 6:58 pm
I have pretty much the same adapter which I used to use with a machine without PS/2 ports and both devices worked together. I don't have any PS/2 mice left so can't test it any more but was going to try it with an old PS/2 keyboard when (if) I get a PI.33
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by MattHawkinsUK » Sun Feb 26, 2012 10:44 pm
I use a similar device at work on a laptop. The moulded plastic round the USB plug appears to contain some electronics so I believe it is "active". Never tried it with any vintage PS/2 devices but I'm sure it will work.

Whether it would work under Linux I do not know. I will be able to test as soon as I get a PI :-)

As far as I am aware it presents two USB devices to the port you plug it in, so I don't see why it wouldn't work with any PS/2 keyboard or mouse.
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by HB » Mon Feb 27, 2012 1:36 am
I've used one with Linux, and it worked fine for me. Of course, technology being what it is, what works for me may or may not work for you. If you've already got one, it can't hurt to try it, but if you'd need to buy one you may as well just buy a cheap new USB keyboard and/or mouse.
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by Millillion » Tue Feb 28, 2012 4:03 pm
Hi, I had the same question a few days ago and discovered that USB - PS/2 converters that come in cable form with a plastic block at the cable junction (like the one you have a picture of) do all the required work onboard and require no drivers of any kind because they simply make the keyboard/mouse look like a generic USB Human Interface Device to the computer.

So, to answer your question, you should have absolutely no problem aside from device specific problems or low quality adapters that make things laggy.
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by grumpyoldgit » Tue Feb 28, 2012 4:14 pm
Even though I was a bit dubious, it is so cheap I have ordered one.
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by arm2 » Sat Mar 03, 2012 12:41 pm
The adaptor 'should' work. We have been selling what looks like that identical adaptor for use with the Iyonix ARM based PC for years. But we have had some batches that look identical but withg a different Vendor and Product USB ID and didn't work:-(

As soon as we can lay our hands on an RPi that is one of the things we will be testing. Though compatibility may be OS Distribution specific.
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by grumpyoldgit » Sat Mar 03, 2012 1:32 pm
I bought one of these

http://www.amazon.co.uk/gp/pro.....00_details

for £1.21, inc P&P.

It works on my decrepit Ubuntu system, with one reservation.

The | \ (usually to left of Z) does not work. If you look at some of the comments for these devices on Amazon, a number of people make the same comment and recommend the following:-

You can generate these chars in Windows by holding down the Alt key and typing the char ASCII code on the num pad (not the main k/b numbers). Ensure num-lock is on. So:

'|' is ALT-124
'\' is ALT-92

As I'm in Linux these instructions don't seem to work, however you can get them by using the Alt Gr key instead.

|  Alt Gr plus key to left of 1(the ¬` key)

\  Alt Gr plus key to right of 0 (the _- key)
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by jojopi » Sat Mar 03, 2012 2:12 pm
Grumpyoldgit said:

The | \ (usually to left of Z) does not work.

That is a serious fault that suggests they never tested it with non-US keyboards.  Also very inconvenient for programming.

I have two of these, of different designs, and both of mine have faults too!

One works perfectly in Linux (I am using it now) but stops working in the BIOS after the first keystroke, presumably due to some quirk in its USB HID implementation.  (Yes, the BIOS does support USB keyboards; it is a USB-only motherboard.)

The other occasionally sends random mouse clicks when the mouse is moved, generally pasting huge blocks of text into random shell windows, which makes it dangerous and unusable.  (I suspect it is getting the data out of sync on the PS/2 side.)

My conclusion is that these devices are generally pretty shonky.  I intend to make my own with a PIC18F2550 one day.
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by darkcity » Mon Mar 05, 2012 3:34 pm
car boots are good for cheap mice.  Got an optical usb mouse for 50p ; -)
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by Burngate » Mon Mar 05, 2012 6:13 pm
I've also got something similar. But in my case, the mouse / keyboard are routed as ps2 through a KVM switch (by chance, sold to me by arm2 just above!). That works well while switched to the Risc PC, the Arm9Home or the windowsbox as ps2, but for the laptop (which has no ps2 sockets) I use this splitter-dongle-usb-thingy.

So does it work? hmm. Sort-of. But it gets its knickers twisted quite often - a string of n's, shift key or ctrl key stuck on, that sort of thing.
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by qlue » Sat Aug 11, 2012 9:04 am
I have a similar looking adaptor that works fine with Linux, but won't work with my RPi. I think the usb port power output is too low. :(
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