Electronics > Projects, Designs, and Technical Stuff

PS2 keyboard controller

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cowasaki:
I have this IC from an old Compaq keyboard.  I need to use it to make a controller for about 40 buttons for a computer game.  I can't find a data sheet and can't be sure I have the IC type number.  All I need is the be able to identify the rows and columns.

I have actually got two new Holtek keyboard controllers but I was trying to be lazy as this board is basically already made! 

magic:
Many old PS/2 keyboards simply contain some general purpose MCU running proprietary firmware with no public documentation.
If that's the case, you can only try to short various contacts and see what characters are generated.

cowasaki:
To be honest that will end up being my first option...  I was just hoping someone recognised the IC.  I do have a couple of Holtek HT82K629A-40DIPLF ICs I bought which are a dedicated USB/PS2 controller but I would have to build a PCB for it some thought that it would save some time if I could just use this from an old keyboard.

amyk:
The routing of the traces and the fact that a quick Google for the part number shows images of it being used on other keyboards suggests that this is at least a semi-standard part, as otherwise they would be routed in a far more straightforward fashion.

If you power it on and probe the pins you should be able to see the periodic scanning pulses on the outputs; what's left will then theoretically be the inputs.

The images I mentioned above may also be helpful in determining which pins do what.

cowasaki:

--- Quote from: amyk on May 11, 2019, 12:04:15 am ---The routing of the traces and the fact that a quick Google for the part number shows images of it being used on other keyboards suggests that this is at least a semi-standard part, as otherwise they would be routed in a far more straightforward fashion.

If you power it on and probe the pins you should be able to see the periodic scanning pulses on the outputs; what's left will then theoretically be the inputs.

The images I mentioned above may also be helpful in determining which pins do what.

--- End quote ---

Arrr yes, good idea I shall have a look.

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