When I first built my machine one of the first problems I encountered was an inability to easily access both the machine and its controls simultaneously. Buying a pendant was out of the question and microcontrollers are a pain, but luckily I recalled hearing about people hacking their old keyboards for custom gaming controllers back in the 90's. At the time I thought it must of been hard but now that I know better I got that old dusty keyboard out of the closet(I know you have one too), rustled up some switches, a prototype board, and bought a suitable enclosure at radioshack. And here it is:
It plugs right into the keyboard port. I use an old laptop so a full keyboard is also accessible. You could also use a cable splitter. This project can be hardwired to control any function on any program that utilizes keystrokes. Heres a quickie Tutorial to get you started on your own custom controller:
Materials:
- 1 old dusty keyboard (will be cannibalized)
- assorted switches, mostly N.O. momentary contact
- 1 enclosure (buy one or use your imagination)
- old floppy disk ribbon cable or other wire
- zip ties, 1 rubber grommet, standoffs or insulating paper for metal enclosures
Step 1: Preparation
Open up that keyboard and remove the circuit board inside and keep the cable for later. You can see mine in the top picture. It'll have two rows of contacts on it, one for rows and one for columns. connect any one row with one column and wallah a key press. I had to lightly sand off some carbon for soldering. Now strip out two lengths of ribbon cable for soldering to the contacts(4-5in). I had 8 rows and 18 columns. Don't forget to tin the other sides of the wires. This takes a bit of practice and patience, but it all pays off in the end.
Step 2: Discovery
Now get yourself a breadboard and connect the row and column wires so each wire has its own track. Here's what I did. I marked the first wire in each length with a permanent marker. Then I downloaded a keyboard test program and made a table of each row/column combination by connecting jumpers between them and observing the results on the program. Now decide which functions you want to use and consult your table. If I wanted to press f6 I would consult the table and connect row 3 and column 8 (yours will probably be different). You can connect multiple switches at once but some may have unexpected results. For more info look for keyboard ghosting in Google.
Step 3 :Ratsnest
Once testing all my switch combinations, I soldered up my mess of wires on a protoboard just like on the breadboard. Then I drilled some holes for switches and finished it with some fine steel wool and acrylic spray. Now wrap it up in your enclosure, and pretend the inside looks as good as the outside. If you ever need a new function added on, get some switches and drill a new hole. I need to add a feed override switch to mine.
Tips:
- Keep your table for future reference
- label your switches
- insulate the inside of metal enclosures
- I have one non-momentary switch and if its on when I start my computer the keyboard wont work until I turn it off.
- rubber grommets and zip ties make suitable strain reliefs
Posts
