USB to PS/2 Convertor

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Introduction: USB to PS/2 Convertor

Here i will show you a simple tutorial to convert your USB keyboard to comfortably adapt to a PS/2 connector in a computer.

The Situation
I had actually bought a flexible keyboard from the market and i had no idea that it had a USB socket to the output. I was using this USB keyboard for a couple of days and after using it for some time it was giving me trouble. Sometimes the keys did not function properly and sometimes it would automatically eject i.e disconnect from the computer port and again connect. I was having such problem and decided to find a solution for it.

The conception
After doing a bit of research i found out that most of the modern keyboards can be easily adapted to a PS/2 connector with ease. The only thing you need is just the USB socket and a PS/2 Jack (i got mine from an old mouse of mine). I also found out that when you buy a keyboard and if it is for the long run like in a Personal Computer, then it is better to have a PS/2 connector bought. Since the flaws for buying a USB keyboard are (i) It is gonna occupy one of the USB slots in your computer and hence there will be no space for USB when you are connecting multiple com ports. (ii)It is gonna use some kind of processor time since it has plugged into a USB. Very nice to have one more empty USB connector
Therefore my suggestion for you all if you are buying for a Personal Computer is to buy a PS/2 keyboard in place of USB. But again if you have already bought it then this instructables is gonna teach you how to accomplish the feat.

Step 1: The Project

Parts needed:-
1. USB SOCKET 1 PCS
2. PS2 JACK 1 PCS
3. CABLE HAVING 4 WIRES. (ANY)

Then the only thing you have to do is see the circuit diagram that i have submitted here and solder the wires according to the pins. You are then done.
Your USB keyboard will be hooked to a PS/2 converter and will work just fine.
It should also be noted that some old keyboards will not work as the parts used inside the old keyboards will not generate the required cock timings required for the motherboard to comply with it.
But most of the Keyboard will definitely work.

Step 2: Analysis and Completion

Now after you have successfully wired the USB socket with the PS/2 jack, it's time to test weather the connection were made rightly. Check the continuity of the wires.
Then finally apply some duct tapes or paper tapes to conceal the hotglue remainings so that the wire gets a rigid shape.
And finally your DIY cable is complete.

2 People Made This Project!

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Tips

Questions

I have a question: I have an USB keyboard and an arduino to control the keyboard. The arduino supports only the PS/2 connector. I have a USB-PS/2 converter. It not work. Can I use this to make the USB keyboard working? Thanks!

37 Comments

That is possible but in some cases the wiring in the mouse plug is different and you would need to change some of the pins.

If that is the case, the correction below should work.

For data use pin 2 of the ps/2 and connect that to pin 2 on the usb

For clock use pin 6 of the ps/2 and connect that to pin 3 on the usb.

Proper ps/2 connectors are colour coded, e.g. purple is keyboard and green is mouse this is reflected on the sockets on the back of the computer to make sure the correctly wired plug is installed.

Most "modern" ps/2 computers are fully wired up on both sockets, but plugs aren't.

i have a ps2 optical mouse, i want to make a USB connector for that. Is it possible to follow the same circuit diagram for that. (i have usb male connector and ps2 female connector)

man... this is great... this is what I've been looking for... Thank You.

Can I do the opposite with it i.e from Ps/2 to USB conversion

1 reply

Actually for reversing you have ready made adapters available. These have 1 USB plug that will plug into the port on the PC and have 2 pigtails to accepy PS2 mouse and keyboard. Look up on dx.com or aliexpres. These are quite cheap and work VERY well.

can i reverse it ? i want to convert the PS/2 keyboard to USB ?

1 reply

Nice mod sir, congrats :). I have a Saitek ST220 Digital Joystick with
an old 15 pin game port connector. Is it possible to mod it into usb?.
Problem is device driver availability. After intensive search no one
seems to have published a mod like that. Someone published an usb ball
mouse steering wheel mod very nice, and I'm thinking this mouse circuit
board could be used for the Joystick.
http://usabuzz.net/page/watch/vid2016WoABrWUetfA

ha all of you are talking sophisticated, it's ironic because usually comment sections go straight to hell, occasionally come back, and plunge ever deeper into the abyss of rude language, but here the "be nice" policy seems to actually be working.

Nice Idea..

This will not work.
The PS/2 keyboard is like I2C serial device. It has clock and data lines.
The hardware inside a PS/2 keyboard doesn't have capabilities to emulate a USB HID device as a USB keyboard.
Hence USB will give message device not recognized.

5 replies

Well Mr. Basak!!
I think you have not read my instructables properly. I have already mentioned in my instructable that only some recent usb keyboard can be adapted for this method. And for your information i have already tested in my PC and it is working 100%. you can see the pictures in the instructables given.
And thanks for you comment

arupbsk is saying that a PS/2 to USB adapter won't work. He is correct.

You ralkut are arguing that he has not read your instructable properly, but you have in fact not read his comment properly and assume that he is saying that your instructable will not work. He is not. His comment is likely an answer to lukeD's question above.

lukeD, having tried it and researched it I can concur. It does NOT work.

Then it may be because of manufacturers making same COB IC for keyboards whether it is PS2 or USB.
Otherwise, theoretically it seems impossible because of different topologies in these two types of keyboards, which prevent them from interchanging interfaces (USB to PS2, or vice versa).

Anyway, thanks for writing a detailed instructable.

That is correct, and it has nothing to do with how recent the keyboard model is. Most USB keyboards are USB only, but some are USB+PS/2 compatible. It will say on the box if the USB keyboard will work with PS/2, and such keyboards usually come with a plug adapter that performs the same function as this DIY cable.

Certain keyboards have PS/2 support without having PS/2 output, just over these kinds of adapters

Will this work the other way around? To get a PS/2 keyboard connected to USB? Thanks!

Can I make it the other way around (PS/2 to USB) with this method?

The information given here, also inadvertently states that if I wanted to Convert a USB to PS/2 Optical mouse that this information would be valid. The reason I ask is I have a Microsoft Comfort Optical mouse 3000. To which I have been using as a PS/2 mouse with the USB to PS/2 Adapter however recently the adapters (two) have stopped functioning. And Using the mouse as USB bothers me because it ejects it's self automatically after about 30 seconds and makes That sound when you eject a device, however once you move the mouse that irritating sound once again emits and begins functioning after a brief pause.

can i use ps/2 cable to make an LED torch...?