THE CONCEPT

We all know that Live allows you to map keyboard characters to pretty much any function within the DAW - REC, PLAY, STOP etc on each track; turning FX on and off; triggering a fade-out, playing MIDI instruments etc (other DAWs may do the same). I came across this webpage:

http://createdigitalmusic.com/2007/08/02/get-loopy-with-the-diy-10-ableton-footcontroller-no-soldering-required

Where a guy removed most of the keys on a USB keyboard, leaving a few remaining which he could control with his feet, for hands-free looping control.

I thought this was pretty cool (and a very cheap alternative compared with a commercial pedalboard which are upward of £130) so copied his idea. However a USB keyboard is kinda limited:

- keys are too small and low-profile, meaning it is hard to find the right one with your feet
- keyboard is too lightweight and flat, meaning it skates around on the floor when I am searching for the right key, and it is hard to access the rear row of keys without hitting the front row
- not enough room for as many switches as I wanted (could only fit 2 rows of 6 switches if I used a sensible key spacing)

I thought the concept could be MUCH improved by taking the buttons out of the keyboard form factor and into a more robust case. The image/form factor I had in mind was along these lines:



PROTOTYPE

The important component is the PCB controller card from inside any old USB keyboard:



In a standard configuration (inside a keyboard!), characters are output to your PC by shorting terminals on one side of the card to terminals on the other. This is normally achieved when a key on the keyboard is pressed against a membrane, allowing conductive traces on 2 sheets of plastic to be briefly contacted together.

I want to take that concept and use proper momentary footswitches to achive the same result.

After some experimentation I cobbled something together from a cheap plastic parts organiser and a few switches:



Which certainly proved the concept, but was not ideal (not enough switches, wrong form-factor etc).

I figured I'd do a proper job, and it turned out pretty well. So... here's a complete guide to building your own!


MARK II

Just so you know where I'm headed, here's the finished product:



Materials required:

- sheet of 6mm MDF
- 15mm square-section stripwood
- momentary switches (I used 21, but you could make a very functional device with 8-12)
- fine gauge wire (solid core is easier to work with)
- old USB keyboard
- salvaged ribbon cable (I used an old PC IDE cable)
- terminal block
- LED mount grommit
- glue, screws and nails/tacks
- 12mm washers

Total cost was around £40, but I have PLENTY of MDF/glue/nails/screws etc left over.


BASE

I wanted enough space for LOTS of switches, and plenty of room between them so I can locate them with my feet. I used Pythagoras' Theorem and trigonometry (for the first time since high school...) to work out the dimensions of my base, lid, font, back and side panels... here are my rough plans:



I have gone for a width of 560mm because my POD XT Live is 520mm wide, meaning I can add 'feet' to raise my DIY controller above my POD so they share the same footprint, i.e:





I have gone for a pitch of 30 deg so make it easy to access buttons at the back without hitting the ones in front.

The MDF sheets were cut to size and glued/tacked together. 15mm bead was used on the internal corners to add strength. I covered the outside of the box and lid with wood-effect Fablon (self-adhesive vinyl wrap found in DIY stores):




THE LID

As seen in the above picture, I drilled 21 holes and attached the footswitches. I reversed it and wired them together in a grid:



This left me with a bundle of 3 wires (one running along each row, commoning 1 side of each switch in the row together), and a bundle of 7 wires (one running down each column, commoning together the OTHER side of each switch in that column).

NEXT - the PCB etc...

THE PCB

Note: I found a VERY useful resource on rejigging a keyboard controller card here:

http://www.geocities.com/AirPanther/keyboard.htm (using a USB controller card in a flight sim application)


As explained in the PROTOTYPE section, different characters are produced by a matrix of combinations of terminals from the LHS and the RHS of the keyboard PCB. This is normally handled by the arrangement of the conductive tracks on the plastic sheets inside your keyboard, so we need to replicate it in our wiring layout:

Separate the three sheets and discard the inner blank sheet as it serves no purpose here. Examine the bottom sheet; you should notice that groups of character terminals share particular conductive traces, all the way back to the region at the top right where they interface with the keyboard PCB.

Select three groups of characters you would like to output, making sure that the three groups each share one particular conductive trace:



I have chosen the following and indicated them on the sheet:

- track 4: F1, 2, W, S, X, \ and CAPS
- track 6: 4, 5, R, T, F, G, V, B
- track 7: 6, 7, Y, U, H, J, N, M

Allowing for (7+8+8) i.e. 23 characters, depending on the number of switches I use. You could build an 8-output board with only 1 group of charcters (and one conductive trace from the bottom sheet)

Now, overlay the top sheet on top of the bottom, and mark the terminals on that one too:



Each track on this sheet will lead back to 1 of 8 terminals at the PCB. You can trace the route by hand (tedious and tricky to distinguish between all the parallel lines) OR you can do it the easy way with a meter. Simply place a probe on the character terminal you wish to trace, then run the OTHER probe along the 8 'contenders' at the top right:



The needle will deflect when you have found the correct one.

I drew a table in Excel with three columns:

Character
Terminal# on bottom sheet
Terminal# on top sheet

And created a matrix of all possible charecters by quickly tracing them with the meter. I.e. shorting terminal 4 on the bottom sheet with terminal 1 on the top sheet will output a F1 character; shorting 4 to 2 gives a 2, shorting 4 to 3 gives a W etc...

Now we need a way of attaching the footswitches to replicate the action of these plastic sheets. The REALLY tricky bit is attaching stuff to the keyboard PCB; normally the conductive traces are held against it by a small metal strip and piece of rubber acting as a clamp within the keyboard case. I am going to replace that with soldered connections... and herein lies the problem; the terminals are approx 1mm wide with only a 1mm gap in between. Also the PCB is covered with a varnish which melts and gets right in the way when you attempt to solder anywhere near it.

To reduce the number of soldered connections to a minimum, I decided to solder some fine 'lead wires' from the PCB to a terminal block, and to make all other conenctions to that.

I had very little soldering experience before I started, and required a bit of practice to get my soldering skills good enough to get it right. I used an IDE ribbon cable in the end, as it has VERY FINE solid copper cores, was reasonably flexible, and could be managed very easily thanks to the ribbon design. First, carefully remove the varnish from the the terminal area of the PCB (5 minutes rubbing with steel wool) so it doesn't gunk up your soldering work. Then tin the terminals and the stripped ends of your wires:



If you do this well, all you need is a very quick application of the soldering iron tip to reflow the solder and make a neat join. TIP: use a bright light and some sort of 'helping hands' device to hold you parts in place as you work!

Finished soldering:



Was pretty happy with this, considering the ugly, blobby soldering work I did on the prototype. Well worth getting some practice in before you ruin a working keyboard PCB!

I was able to use the original metal/rubber clamp from the keyboard to secure the wires in place (used three bolts to hold it all together:



That ain't going anywhere!

At this point I also removed the CAPS LED from the PCB. If I include CAPS as one of my switches, I can use this to DOUBLE UP on the number of unique characters I can output from my controller. The LED will indicate whether I am sending upper or lower case characters - i.e. BANK 1 or BANK 2...



It was very simple to gently unsolder the LED and replace it with two long wires to run the LED to the front of the case (the LED now sits in a rubber grommit which cost around 7p).

FINAL ASSEMBLY

All that now remains is to connect the switches and wiring loom on the lid to the PCB via a terminal block:



Very conveniently, the bolts holding the PCB together fitted almost exactly into the holes on top of the terminal block (not shown in pic), so I could stack one upon the other, leaving nothing dangling around inside the case.

I stuck little rubber self-adhesive feet to the underside of the base, and ran adhesive window/door-sealing foam strip around the upper surfaces to provide a tight seal.
Added the lid:





Pretty much done! Each switch sends a unique character to my PC (tested in notepad); the CAPS footswitch performs as expected, i.e. changing characters to CAPS and lighting the BANK LED (top right of lid).

I now have 21 buttons, 20 of which send up to 40 unique outputs depending on the status of the BANK switch...

The main intended use will be to control REC, PLAY and STOP for each of 12 separate tracks in Live, leaving three switches for:

- CAPS (i.e. BANK)
- Stop/fade out all tracks
- Tap tempo/engage metronome

Of course I can dynamically re-assign any function during a Live session by activating the Key Mapping function - without stopping the music.


Sure beats a Boss looping pedal, doesn't it?

Feel free to copy my design and use this thread for any questions you may have!

Very cool post, thanks!

Please, where didi you buy these metal momentary switches? The one I found seemed very expensive to me...

I *had* been looking at Maplins.co.uk but they were close to £4 each. Then I found these:

http://www.rapidonline.com/Electronic-Components/Switches/Push-Button-Switches/Foot-switches/79208

£1.04 each in quantities of 10 or more. Seem just as robust as those on my guitar pedals etc. Euro and US links at the top right of the home page.

Brilliant! Thanks for sharing.

.m

I kinda thought it might go down well on this forum! I posted this guide on a guitar forum I go to as well and they weren't very interested...

Building the base took the longest amount of time and required the builk of the tools. If possible I would recommend using an existing enclosure if you have something suitable. A flat box can be used with wedges underneath to raise it to the right angle!

If you had a suitable enclosure and only wanted 10 switches (say, 2 rows of 5, plus one for CAPS to allow you to control 10 tracks) you could build this in a few hours.

(one and only) bump...

thats one damn sexy footswitch right there man.

very cool post

thanks for sharing

thank you so much, this is wonderful!

so there are two keyboards connected (the footswitch one and a real one).. i wonder how the computer reacts:
* just one keyboard works?
* or both work simultanously?
* is there difference between usb + ps/2 keyboard compared to two usb keyboards connected?

Yes, both keyboards work simultaneously, so if you are using AutoHotkey to convert your controller outputs into more memorable characters for Live (I use QWERTYUIO to trigger rec/play in each clip slot, ASDFGHJKL to stop the same tracks), you need to right-click the system tray icon and briefly suspend your Hotkey script if you need to type something.

Never tried a PS2 keyboard but there's no reason it shouldn't work in exactly the same way.

What would be REALLY cool would be to use the innards of a *wireless* keyboard... hey presto, a wireless foot controller!

you can run it through glovepie, because then you can tell glovepie to only take the keyboard input from usb hid 1 (your diy controller then) and translate it into something else instead, midi messages for example, and take input from usb hid device 2 (your "normal keyboard) and do nothing with it so that it still works as a regular keyboard.

Cool tip about glovepie.