Really need assistance with specific keyboard for case mod


2 posts
by zunebuggy » Wed Aug 07, 2013 12:31 pm
Please see attached images. I have an ELC-001 and after measuring, I know the Pi I have will fit inside it. The ELC-001 is a toy messaging device that allows two people to type on a keyboard and view each others message through an eyepiece. Basically it is a walkie talkie but instead of voice, it sends text and it has a headset with an eyepiece that projects onto the right eye, a very red display (like a low tech Borg from Star Trek). Even if you do not know anything about the ELC-001, I have included pictures of the keyboard, the simple keyboard circuit board and the ribbon cable coming from the board.

My question is this. I just want to use the keyboard. The rest of the messaging circuit I plan on removing. The keyboard is 36 switch contacts wired in a simple matrix that goes to a 14 wire matrix. Is there a way to convert this to work with the Raspberry Pi? I

I like this case because it has a keyboard that you wear on your wrist, the Pi fits and I am planning on replacing the cheap ELC-001 eyepiece with a pair of MyVu glasses I own and know they already work well with the Pi.

My phone has unlimited data and will tether to my Pi as a Wifi Router using the software FoxFi. I have made battery packs to power it all and keep it all running for several hours. I even plan on mounting a webcam in my cap and then I can live stream while hiking.

This has been my dream for a while and if I can get the keyboard working it will be great.

I CAN print my own circuit boards. If possible, if you do know a similar keyboard circuit that is known to work with the pi (obviously the switches will not line up with my keyboard), I can replace just the switches only and design the circuit board with switch contacts in the same position as the one shown so that it will work with my keyboard.

Thank you for any technical help.
Attachments
switch_contact_board.JPG
switch_contact_board.JPG (44.61 KiB) Viewed 619 times
ribbon_cable.JPG
ribbon_cable.JPG (59.21 KiB) Viewed 619 times
keyboard.JPG
keyboard.JPG (43.66 KiB) Viewed 619 times
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Joined: Wed Aug 07, 2013 11:52 am
by ame » Tue Aug 13, 2013 2:26 am
I can suggest two ways to do it. There are probably others.

1) Wire up the Pi's GPIO lines to the keyboard matrix and write a program that loops around looking for key presses. Here's a general outline of the technique:
http://www.8051projects.net/keypad-inte ... uction.php

A disadvantage of this is there is a lot of wiring to the Pi itself and you use up a lot of I/Os. Plus you have to write some software.

2) Take apart an old PC keyboard and remove the controller board. Wire up your keyboard matrix in place of the original keyboard matrix. The advantage of this is it should behave like any other keyboard when you plug it in. Here are some examples:
http://runawaybrainz.blogspot.kr/2012/0 ... rpose.html
http://www.mp3car.com/input-devices/128 ... atrix.html
http://scramtronic.tumblr.com/post/1966 ... board-hack

A disadvantage of this is your keyboard matrix might not be wired in the same way as the original keyboard matrix. You might have to add some sort of translation software to map the actual keypress to its corresponding key. This might get tricky for special keys such as 'shift' or 'ctrl'.

Good luck.
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