Search:
Submit Search


Adding MIDI to a pedalboard

Building organ consoles for use with Hauptwerk, adding MIDI to existing consoles, obtaining parts, ...

Adding MIDI to a pedalboard

Postby wiznap » Tue Jun 05, 2018 1:50 pm

Hi to everybody.

I wish to share with you my notes for the project of adding MIDI to an organ pedalboard. I hope my notes can be useful to all those that wish to MIDIfy existing pedalboards and even keyboards or any other sort of buttons.

The goal of my project was to replace an old noisy and very light-touch (to my taste) pedalboard.

I am lucky to know an old friend who builds/restores pipe organs and historical instruments for a living (Massimo Elice). I commissioned him a 32 notes concave/parallel BDO pedalboard like the one he puts in the regular pipe organs.

The result is a solid, fully built in solid ash tree pedalboard without compass springs but with rear spring steel. This allows some sort of regulation for the lightness/strength of the touch.

Nice. I am very happy with it.

Because this is a pedalboard "thought and built" for a regular pipe organ, I needed to take care of the generation of the MIDI messages in order to connect it to my Hauptwerk system.

Here, my electronic engineering background helped me. I opted for a solution with Hall sensors and little magnets for capturing the pedal movements and for an Arduino Leonardo to transform the signals detected with the Hall sensors into MIDI "Note On", "Note Off" events.

Arduino is an open source hardware project with single board microcontrollers and a software Integrated Development Environment (IDE) that makes very easy to program the microcontroller by using a C like language.

I chose the Arduino Leonardo instead of the Arduino UNO because Leonardo has an ATmega32u4 which supports USB, whereas the UNO has an ATmega328 which doesn't have USB support onboard. Other than that the two boards are basically the same.

Indeed the UNO could be used too, but the process to build a similar system with it, is slightly more complex. With Leonardo all the difficulties are gone and you don't even need a MIDI plug because the onboard micro USB go straight into the PC USB port. So, no need of any MIDI-to-USB boxes.
The 32 Hall sensors are connected in a 4x8 matrix and so use only 12 pins of the Arduino board, leaving 8 pins free for additional connections (having a 4 manuals organ, I plan to use 4 potentiometers for sweller and expressive pedals). They are connected directly into the onboard pins.

By following and combining together several code examples I found on the net, I wrote a fairly simple program to read the sensor state and create the MIDI events by using the MIDIUSB Arduino library. Of course I can change the MIDI channel programmatically as I wish. The power to the sensor is provided by the Arduino which is powered by the USB.

As you can understand, I consider the simplicity of the solution the main advantage and the success of this project.

In terms of costs, besides the pedalboard, the Hall sensors cost few Euros by the hundreds and the Leonardo (original) is €18.00 from the Arduino web site (but given the fact it's a Open Source project you can find also cheaper clones. I did not test any of these).

I posted few pictures in Flickr, available here.

-Carlo
wiznap
Member
 
Posts: 10
Joined: Mon Sep 29, 2008 8:05 am
Location: Nice area - South of France

Re: Adding MIDI to a pedalboard

Postby EricJ » Fri Jun 08, 2018 5:59 pm

Carlo, Thank you for starting this topic. I am embarking on this same project myself. I look forward to any updates you have, especially regarding magnet size, type, polarity alignment, and their effect on controlling the speaking point.

I have one question. Everything I read indicates that Hall Effect Sensors are the best approach and I will use it as well. However, it seems that all the commercial consoles that describe their technology only use reed switches. Is that just because they are slow to adapt? Hall effect sensors have been around for a long time as best I know.
EricJ
Member
 
Posts: 4
Joined: Tue Sep 12, 2017 1:27 pm

Re: Adding MIDI to a pedalboard

Postby organtechnology » Fri Jun 08, 2018 8:27 pm

Hi Carlo,
The use of Hall effect sensors for a pedal board is second best in my opinion. I think the easyist most reliable way is with optical interruptor modules where an opaque flag interrupts the light beam across the sensor. The Hall effect devices are a little fussier due to the width of the magnetic field from some magnets. Sometimes they interfere with the pedals on either side.

This can also be a problem in reed switch type pedal boards. There can also be a case of magnetic interuptor modules but these must be self made.

We are working on releasing a relatively simple to install optical system for both keyboards and pedal boards. If you would like to be a beta tester, please contact me. The pedal board system consists of 33 boards 32 for the pedals and one combiner board to terminate the wiring harness. The wiring is 'punch down' connectors with no soldering and the 32 sensor boards are to be offered fully assembled. The optical system is designed to work with Midi-Hardware (Roman Sowa) and with the MGB HWCE encoder system.

Best regards,

Thomas
Complete VPO systems powered by Hauptwerk™. Real Wood Consoles, PC or MAC Computer Sound Modules, Audio for Home or Church.
info (at) organtechnology.com http://www.organtechnology.com

Authorized Hauptwerk Dealer; Milan Digital Audio Dealer..
User avatar
organtechnology
Member
 
Posts: 1714
Joined: Sun Aug 02, 2009 5:58 pm
Location: DFW, TX USA

Re: Adding MIDI to a pedalboard

Postby GrahamH » Sat Jun 09, 2018 9:01 am

I agree with Thomas, here.
Having recently fitted a pedal board with photo-interrupters, I don't think I'll be going back to reed switches.
Suitable photo-interrupters are less expensive than the equivalent reed switch + magnet combination, and easier to adjust. As far as I can see, their only disadvantage compared to reed switches is that they need powering.
I can't see the attraction of Hall Effect sensors at all. Not only do they require magnets with all their associated complications, they also need to be powered.

Graham.
GrahamH
Member
 
Posts: 512
Joined: Tue Sep 09, 2008 7:39 am
Location: Near Manchester, England

Re: Adding MIDI to a pedalboard

Postby wiznap » Sat Jun 09, 2018 9:50 am

@EricJ

I did not experiment with reed switches for 2 reasons: the first is very basic: I had many Hall sensors sitting in my drawer :-D.... The second is more serious because I did not want to add either diodes or any other kind of additional chips (mux or shift registers) and/or resistors. With Hall sensors and the Arduino Leonardo everything came out pretty neat: I had just to solder the cables from the sensors to the board pins.

I use 5x2(mm) magnets (sorry I don't have the specs for the strength, but their magnetic field does not "seem" very strong). While experimenting on the breadboard, my observations are: they trigger the Hall effect up to ~10mm distance coming from the front. They trigger the "on" while ~50-60% in front when sliding up to down, and conversely the "off". I purposely wanted something that was fuzzy enough to not having me to spend too much time in a "precision" position setup. Once all was wired, I noticed that all worked with an approximate positioning while pushing the pedals with the hands (magnet in front of the sensor when pedal is down). I fine tuned the position of the magnets once the pedalboard was positioned in its place and I was putting the "foot" push strength.

I just ordered a 8x3(mm) magnets to evaluate if there is any advantage in position tolerance, but so far, I can play with no problems as it is.

Overall, I must admit it was a very fast tuning to find the right position (BTW: the magnets are attached with some UHU patafix glue pad that allows an easy reposition if needed. I can postpone the definitive fix after I test the new magnets).

Regarding polarity it is pretty easy: normally Hall sensors, as you imply, have, let's say, an "orientation". So, if you mount them all in the same, consistent way, you only have to determine if it is the "north" or the "south" of the magnet that triggers the sensor. You need to determine this only for the first magnet, because all the remaining magnets will be positioned with the same orientation.

Regarding the switching speed, I did not notice any difference from my previous old pedalboard that uses reed switches.

Regarding magnetic field interference. The magnets on the pedals are at about 30-35 mm apart. On a flat, smooth surface their magnetic fields start to interfere at about 22mm. Indeed I did not notice any interference in the mount. I am curious to test the new (8x3mm) magnets to verify if the absence of interference persists.


@Thomas

Thanks for your comments. I agree with what you say, even if I'd like to appreciate how easy would be the initial positioning and the tolerance to position variations while playing, of the various light beams.

Then there is also some cost-benefit analysis aspect that need to be evaluated.

I would be very happy to beta test your solution. Let's take this offline as a PM.

Only one caveat though: for my 32 inputs (and not only), even if I understand your solution is a packaged, "no-soldering" one (nice), I'd like to keep the Arduino interface instead of going with the Midi-Hardware and encoder....a potential variant? ;-)

@Graham

As you understand from my above message to Thomas, I did not test the opticals so I can not take position.

Correct: the Hall sensor need power. The power come from the Arduino pins (which take power from the computer USB port), They are powered in a round-robin way, so only few of them (8 in my case) are powered at a time.
wiznap
Member
 
Posts: 10
Joined: Mon Sep 29, 2008 8:05 am
Location: Nice area - South of France

Re: Adding MIDI to a pedalboard

Postby organtechnology » Sat Jun 09, 2018 11:34 am

wiznap wrote:
@Thomas

Thanks for your comments. I agree with what you say, even if I'd like to appreciate how easy would be the initial positioning and the tolerance to position variations while playing, of the various light beams.

Then there is also some cost-benefit analysis aspect that need to be evaluated.

I would be very happy to beta test your solution. Let's take this offline as a PM.

Only one caveat though: for my 32 inputs (and not only), even if I understand your solution is a packaged, "no-soldering" one (nice), I'd like to keep the Arduino interface instead of going with the Midi-Hardware and encoder....a potential variant? ;-)


Whether you can work the system with the Arduino would depend on your scan method and polarity of the scan and data pulses. Ours are tailored to match the expectations of the Midi-Hardware and MGB modules.

I will keep you posted on the progress and we can decide about the beta testing when it is ready.

Thomas
Complete VPO systems powered by Hauptwerk™. Real Wood Consoles, PC or MAC Computer Sound Modules, Audio for Home or Church.
info (at) organtechnology.com http://www.organtechnology.com

Authorized Hauptwerk Dealer; Milan Digital Audio Dealer..
User avatar
organtechnology
Member
 
Posts: 1714
Joined: Sun Aug 02, 2009 5:58 pm
Location: DFW, TX USA


Return to DIY organ consoles / MIDI

Who is online

Users browsing this forum: No registered users and 7 guests