Keyboard Encoders
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My PC recycling buddy made me an offer I couldn't refuse..
20 Dell PS2 keyboards for a couple bucks a piece.
Of course I'll use these in the PC shop and for emergency
keyboards on the road, but it's got me thinking that there
are some wonderful encoder chips waiting to be removed
(from a couple keyboards) and added to my Propeller parts collection.
{perhaps even another entry for the cookbook}
Has anyone already mapped out any of the common keyboard
decoder chips? I haven't cracked one open to get the exact
numbers from the IC, but I've gotta think there can't be that
many of these created since they all do the same function.
Anyone have any data to start with?
Hey 104 inputs and three outputs (LEDs).. What's not to like?
Thanks
OBC
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New to the Propeller?
Getting started with a Propeller Protoboard?
Check out: Introduction to the Proboard & Propeller Cookbook 1.4
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card connected? - PropDOS
20 Dell PS2 keyboards for a couple bucks a piece.
Of course I'll use these in the PC shop and for emergency
keyboards on the road, but it's got me thinking that there
are some wonderful encoder chips waiting to be removed
(from a couple keyboards) and added to my Propeller parts collection.
{perhaps even another entry for the cookbook}
Has anyone already mapped out any of the common keyboard
decoder chips? I haven't cracked one open to get the exact
numbers from the IC, but I've gotta think there can't be that
many of these created since they all do the same function.
Anyone have any data to start with?
Hey 104 inputs and three outputs (LEDs).. What's not to like?
Thanks
OBC
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
New to the Propeller?
Getting started with a Propeller Protoboard?
Check out: Introduction to the Proboard & Propeller Cookbook 1.4
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card connected? - PropDOS
Comments
Most likely the Rows and Columns are condensed into only 24 inputs.... possibly an 16x8 arrangement to accept a maximum of 128 different keys. The Keyboard Chips that I have seen are 40 pin or 32 pin IC's so this would "fit".
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
So, you can't really use it well as logic inputs because the way the keyboard works is that half those lines will be outputs, and the keyboard encoder checks whether the signal put on the lines which were outputs is seen on the lines which are inputs (i.e. that the two were connected by a key press). At most you get 16 inputs, maybe 8 or less.
However, one place this works really well is if you have some other key matrix to decode, then you can hook it up to the PC keyboard lines and it will decode it for you. That was part of the circuit I did for the Propeller design contest - I wanted to decode the keyboard matrix from a toy laptop, so I hooked it up to the decoder board from a real keyboard. You have to do some experimenting to get the best subset of rows and columns to connect to, because not every combination of row and column may be used.
Another place I can see this being useful is if you wanted to read a lot of switches, or if you wanted to make a game controller that you connect to a computer as a keyboard.
An Epoxy blog... Ugh!
Does look like one *might* be able to solder to the edgecard. Messy.
Not at all the DIP I hoped for.
Perhaps I need to find a source of keyboards from about 10 years ago. [noparse]:)[/noparse]
OBC
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
New to the Propeller?
Getting started with a Propeller Protoboard?
Check out: Introduction to the Proboard & Propeller Cookbook 1.4
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card connected? - PropDOS
While you are on the subject ... how about a wireless keyboard for your book?
Rich
I discarded the keyboard recently because it was failing, though. I think one of the rows or columns was not making good contact somewhere. Wish I had kept it around. ^-^''
My point is they do exist, you just gotta look a little older.
Just add a little bit of scanning software (ho-hum) and bit bang the output as PS/2 or serial as you like, why mess with old keyboards?
Well, that's how I see it.
*Peter*
P.S. I now question myself as to why I'm not using the SX chips in place of some of the other peripheral controllers I am now using.
P.S./2 - shouldn't this be in the Sandbox?
(and of course mastery of the 28hour for the additional time required. [noparse]:)[/noparse] )
One of the concepts behind some of my Cookbook projects is making use of materials
which are common around us. Anyone can purchase an "exact" part, but I find it more
interesting to recycle/reuse/reclaim items from things which might otherwise be heading
for the rubbish pile. Of course this attitude really only works on a hobby level.
Sometimes the attitude works, (like the $20 video screens) and other time it fails.
There is good adventure in the attempt..
@Moderators: Yes, this thread is fine for relocation to the Sandbox if deemed necessary.
OBC
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New to the Propeller?
Getting started with a Propeller Protoboard?
Check out: Introduction to the Proboard & Propeller Cookbook 1.4
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card connected? - PropDOS