Baldwin 640 pedalboard conversion

[smccafferty]

I'm attempting to convert a Baldwin 640 pedalboard to midi and hoped I could get some advice. I have no real knowledge or experience with electronics...but I'm somewhat handy and can handle some simple electrical and soldering tasks. I removed the pedalboard from the organ and performed a basic examination. The pedals appear to utilize magnetic switches. I tested the continuity of these switches and believe that they share a common ground and each circuit closes when the pedal is depressed. (see pic of switches attached)

Based on my research I feel that I should be able to simply solder a new wire to each contact and connect it to an Arduino Mega...and then also connect the common ground to the Arduino. I was a bit hesitant to go this route because I have zero experience with coding...but I've seen some posts on this forum that lead me to believe that I'd simply have to copy/paste some coding that members have provided.

Is it this simple? Solder some wires, connect a 5 DIN female MIDI plug, copy/paste some code, and done? I know there are conversion kits available but they seem a little pricey...and require me to replace the switches. I'd prefer to go the Arduino-route and utilize the existing switches...as long as it's do-able by a noob like me! :)

One last question: would it be possible to somehow utilize the existing wiring without having to solder new wires to each switch? Or would this be too complicated? I notice that the existing wiring seems to travel through a circuit board and terminate with two plugs: a 12 pin plug and a six pin plug. I'm guessing that the existence of this circuit board...and the fact that there are 18 pins instead of 32+... would indicate some form of diode matrix? (pics attached) Would there be some way to wire these to the Arduino and adjust the coding such that I wouldn't need to solder 32 new wires to the switches?

Your advice would be greatly appreciated.

[Larason2]

Yes, I think it's doable with an Arduino, and we can certainly help you. The wiring harness does have me a bit confused though. It could have a common ground, but there seem to be some of the top wires have two wires going to them as well. Could we get a closer picture of the switches, and a picture of what the chips on the circuit board are? I don't see any diodes, which would be weird for a matrix, and the pattern doesn't look right either. You also don't need a 16 pin and a 6 pin connector for a matrix! My pedalboard has a 6x7 matrix. I'm wondering if maybe the board has a shift register, and that's how it is accomplished.

Anyway, if you cut all the wires and soldered it to an arduino, then it certainly should work. However, we can probably save you some trouble wiring if we can figure out how it works. If we can't tap into the IC's on the circuit board, it could still save you trouble using some of those wires. Is there a connector onto the circuit board from the pedal board you can disconnect?

[smccafferty]

Thanks for the quick reply. It definitely looks weird to me too…but I don’t know anything…so it all looks weird!!
The pedalboard is at the church but I’ll stop by after work to pick it up and bring it home. I can then partially disassemble the mounting bracket tonight so I can get some better pictures.

[Coenraads]

It looks like this may be a 12 x 3 or 8 x 4 matrix. Check the daisy chained common wires, to see if they apply to groups of 12 keys or 8 keys.
How many wires go into each of the two plugs you show?
We need a closeup of a circuit board carrying a reed switch to look for diodes. If it is matrix wired we can certainly write some custom code to scan it.

If worst comes to worst, we could just join all the common wires together and parallel scan it by running one wire to each switch.
This should be a straightforward conversion either way.
John

[John Kinkennon]

Hopefully someone will provide details on the Balwin 640 pedal wiring. I see magnets on the ends of the pedals but the circuit boards that respond to the magnets have three wires for each note so I'm thinking perhaps it's an 8x4 matrix using Hall Effect sensors. Just a guess. What is essential is to know the circuitry on the matrix board, if that's what the additional board is in the third photo. It appears that the smaller connector just has five contacts with one empty position. Actually it might be twelve columns on one connector with the second having three rows and a pair to provide biasing for five wires total. A good photo of the front and back of the large circuit board could give us the answers. A closeup of a smaller board's component side would help to identify a possible device number.

[Coenraads]

What appear to be three wires to each board I think is only two. Two of the wires appear to connect to the same wire-wrap pin which make me think they are just the daisy chained common wire. My money is on a simple reed switch and nothing more.

[John Kinkennon]

I do believe you are correct.

[smccafferty]

Well I got the pedalboard home and removed the backboard to provide a better view of things. John K is correct...the pedals have magnets on the ends and the switches have 3 wires for each note (except C1 which only has 2 wires). But as Coenraads pointed out...two of the wires are wrapped around one pin and one wire to the other pin. John K is also correct that the small plug only has 5 contacts with one empty position. The other plug has 12 contacts.

I've attached some pics that will hopefully help.

[Larason2]

Interesting. The board on the bottom has diodes all right, but also capacitors and a resistor. The resistor is wired in parallel with the diode, the capacitor across the connection. So I think Coenraads is right that it's a 12x3 matrix, and John is right that it's an array of hall effect sensors.

No IC's to be found! So it should be pretty easy to wire up. I'm guessing one of the contacts on the 5 prong connector is V+, the other ground. The rest of the contacts would each go to a pin on the arduino. What do you guys think?

[Coenraads]

Hall switches require three connections, I only see two, as would be the case for reed switches. We need to see the backside of one of the little switch boards. The main board might be a diode matrix, but what a mess.
If this were mine, I'd strip off all the wires and just parallel wire it to an Arduino.

[smccafferty]

I removed one of the switches so you guys can have a better look. I also started separating the wiring and found that there are 2 wires on the bottom posts of each switch because they are daisy chained from switch-to-switch…just as Coenraads suggested. That’s why C1 only has one wire…that’s where it starts.

[Larason2]

That's definitely a reed switch. So much for my theory!

[smccafferty]

Here’s what I was thinking…
im going to separate all the wires and inspect them for damage and check continuity. If they’re ok I’ll simply cut them to length and strip the ends. Then I’ll get the Arduino Mega with a screw terminal shield and start attaching the wires…starting with C1 in pin 22 and ending with G3 in pin 53. Then of course the common ground to a ground pin. No soldering required 😁
Sound ok?

[Coenraads]

I suggest you do the following. Go ahead and use the screw type breakout board for making all the pedal connections.
Also go ahead and use a MIDI shield and mount it off the Arduino. Using three male to female Dupont connectors, connect +5V, ground and Tx0 by plugging the female ends into the MIDI shield connectors and then connect the male ends to the corresponding screw points on the breakout boards. This will work fine and no soldering!
If you use my program, you need not worry about pull-up resistors. They are not needed.

No need to apologize for asking questions. We all got where we are by asking lots of questions and we're only too happy to help you any way we can.

[Coenraads]

One more thought. Crimping, although doable, is a PITA. And in your case the wires look like they may be 22 gauge or even 20. I think the screw connectors will accommodate these nicely.

[smccafferty]

Coenraads I definitely agree that crimping would've been a huge PITA! That's a lot of connectors to crimp!! I opted for the screw terminal shield instead. I cleaned up all the wiring today in preparation for the delivery of my Arduino, terminal shield, and MIDI shield. These small solid-core wires are in good shape and easy to strip. I think they should work well with the screw terminals and this process should go pretty smooth (fingers crossed).
I also downloaded Arduino IDE today in preparation for copying/pasting your code. I may be bugging you again in the coming days when I get to that step :)

[Coenraads]

smccafferty I think your plan is a good one. By all means salvage as much of the wiring as you can. You may have to link some of the common wires so that there is a single one connecting all the reed switches which will ultimately go to Arduino ground. Screw breakout boards are handy if you don't like soldering but they would prevent you from mounting a MIDI shield. In that case you will have to wire up a 5-pin DIN MIDI connector where you will need two 220 ohm resistors. Where Larason2 says 1/4 amp, I think he means to say 1/4 watt. 1/2 watt would also be fine. Tolerance is not an issue.

Alternatively, you could use a MIDI shield and mount it off the Arduino board. All you need to connect are +5V, ground and Tx0

If you intend to use my parallel code
https://sites.google.com/site/casava...tep-expression
you will see that in the preamble it specifies that bottom C starts at pin 2.

MIDI messages assume bottom C connects to pin 2. Subsequent pins follow the
order: 2 - 12, 14 - 19, 22 - 68.

Should you for some reason, such as wanting to use an onboard MIDI shield, want to use pins 22 to 53 I could modify the code for you. But you may decide to make use of the remaining 32 digital inputs for pistons. There is also provision for a swell pedal and daisy chaining. If you are not hooking up a swell pedal, be sure to connect pin 69 to ground to prevent spurious analog input.

I've wired up many pedal boards and have found the on-board 100k pull-up resistors to be adequate in all case. I've only run into problems with Alan and Galanti where the sense lines are daisy chained from great to swell to pedal.

I assume your reed switches are normally open which is almost always the case.
Edit: This was written before I saw #9.4 and responded with #9.5
John

[Larason2]

Ah, yes sorry. 1/4 watt! 1/2 watt will certainly work, but I think that's paying too much. Now, I haven't heard Allen called "Alan" before!

[Coenraads]

Hmmm... I remembered thinking it looked funny. WWIT. (What was I thinking?)

[smccafferty]

Coenraads Thank you so much for the detailed reply.

I like the idea of using the screw breakout board for the pedals and then using a separate MIDI shield. Easy peasy!!

No need to modify any code for me. I'll hook things up in whatever way you tell me. Just to make sure I've got it:
- I'll connect the pedals to digital pins 2-12, 14-19 and 22-36. I've posted a picture of the breakout board that I was planning to use.
- I would then connect the common ground from the pedalboard to Arduino ground (does it matter which ground pin?)
- I'll connect the Arduino to the MIDI shield by using three male to female Dupont connectors (although I assume I'll be cutting the male end off and stripping the wire to insert into the screw terminal). I'll connect the male end to +5V, ground and Tx0 on the Arduino and then female ends to the corresponding pins of the MIDI shield. Does it matter which +5v and ground pins I use on the Arduino? And is Tx0 the same as digital pin 1?
- I assume I'm supposed to connect Arduino Tx0 to MIDI shield Rx0, right?
- Since I don't plan (at the moment) to use a swell pedal then I'll need to connect pin 69 to ground? So I'll use a small jumper wire to connect pin 69 (A15) to ground? Does it matter which ground pin?

[Larason2]

I'd get something like this. I found that by pushing on the screw terminals I'd get a better connection sometimes. So there may have been problems with how everything was connected inside. I think this particular design makes more sense, as all the soldering points are accessible. https://www.amazon.ca/dp/B01CU3OB5Y/...G9uZV9kZXRhaWw

[smccafferty]

That's a very different design than others I've seen. Looks good. I'll definitely consider this one instead.
What are your thoughts on just getting a Dupont crimp tool kit and simply crimping connectors onto all the pedal wires and attaching them directly to the Arduino without the shield?

[Larason2]

Yes, that works! What I do is buy AWM ribbon wire, and attach an IDC header on the end, then use dupont "jumpers" to connect the flat cable to the arduino. There's a lot of ways to do it, but dupont connectors are practical.

[Coenraads]

I've never used a breakout board because I like soldering, but it sure looks like it would make life easier!

Yes, the pedal switches are connected in the order indicated starting with bottom C at pin 2.
All grounds and 5V power pins are equivalent. I think you'll probably be able to insert the male Dupont connector without having to strip it. Try it and see.
Tx0 is indeed pin 1.
Tx0 on the Arduino connects to Tx0 on the MIDI shield. Rx0 is not used. Think of it this way, If the shield were mounted on the Arduino then the Tx0 pin of the shield would plug into the Tx0 socket on the Arduino. Normally when connecting Arduinos serially, Tx0 of one does indeed go to Rx0 of the next. But this is different.
Pin 69 goes to ground. I always just use the nearest one (at the end of pins 52 and 53).

Hope this helps, and let me know of anything else you may not be certain about.
John

[smccafferty]

Thanks for the clarification. On the MIDI shield pictured I coudn't find a Tx0 pin...only Tx1. Is the label blocked by one of the MIDI ports and I simply can't see it?

[smccafferty]

I looked at the Mega and MIDI shield a little closer...and I think I now realize that the Tx1 on the MIDI shield aligns with the Tx0 on the Arduino.

[Coenraads]

The Arduino Mega has four serial ports, Tx0,Tx1,Tx2 and Tx3.
The Arduino Uno and the shield only have one, labelled Tx. The number one you see beside it is the pin number, not the port number. So Tx0 on a Mega = Tx on the Uno.

[smccafferty]

Perhaps it's a little late in the game to ask this question...but am I correct in my belief that this pedalboard conversion requires that the output be via MIDI? And that I'll subsequently need to use some sort of interface to convert to USB to connect to the computer? I recall reading somewhere that the Mega isn't well suited to MIDI over USB so that's why I assumed the 5 pin DIN connection was required...and why I intend to get the MIDI shield and connect everything as we discussed.

In this regard, is there a particular interface that you would recommend? A simple cable like pictured?

[smccafferty]

I've seen some of the cheap ones online for around $13 that I was avoiding based on bad reviews. I recall reading somewhere on this forum (I think) that you can get a decent cable for around $30...which was roughly the price-point of the one in the picture. But I'm happy to get the Roland if it's a proven high-quality product. Thanks for the recommendation!

[myorgan]

I have never had an issue with a Roland (Edirol) UM-1 series. You can even find them used on some of the online shopping websites.

Michael

[Coenraads]

Indeed the Arduino Mega is not set up for USB MIDI, hence the 5-pin DIN MIDI connection. Many VPOs however, incorporate something like the Focusrite Scarlett 4i4 4th Gen Audio Interface which has 5-pin DIN MIDI connections.
In the absence of such an interface, a simple MIDI to USB converter can be used. And one more vote for the Roland.
Mine has a tiny slide switch to select between an iPad or a computer. Make sure it's in the right position.

[smccafferty]

Thank you to everyone for your help and comments in relation to this pedalboard conversion!! It's all done and working perfectly :)
Special thanks to Coenraads for the code and very specific instructions. Even a noob like me was able to pull it off!!

My original intention with this project was to buy a couple of cheap midi keyboard controllers to replace the existing keyboard manuals on the old Baldwin...pull the controllers from their plastic cases and use some of my carpentry skills to incorporate them into the Baldwin console. But now I think I've found the confidence to dig into this conversion a little more and attempt to convert the existing manuals. I'll head over to the church tomorrow to dig into the wiring of the manuals to see if I can make heads or tails of it.

I'm thinking of just doing the exact same thing I did to the pedalboard. 2 more Arduinos...2 more midi shields...copy/paste the code to each board...connect the keys the exact same way I connected the pedals (pins 2-12, 14-19, 22-68)...2 more Roland UM-1 cables...and done. Sound right?

[Coenraads]

Thanks for letting us know how things worked out. It is always rewarding to see everyone's advice come together leading to a successful outcome.
You call yourself a noob but from your neat work, I'd see you have some fine technical skills. Nice job. I hope your success will encourage others to do the same.

Re the manuals. You just need the two additional Arduinos. One shield, one UM-1 is all you need for the whole system. Over short distances, one Arduino's Tx0 can just be wired directly to the next Arduino's Rx0 as long as all the Arduinos have their grounds connected.

Keep your fingers crossed that the manual key contacts are in good order. Good luck.
John

[smccafferty]

That's sounds easy enough. Thanks again fellas!!

[Coenraads]

Very simple actually:

Serial.write (noteStatusRx + 1); //output on port 0, one channel up
Serial.write (noteNumberRx);
Serial.write (noteVelocityRx);

Adding one to the noteStatusRx does the trick.

[smccafferty]

Do I also need to daisy-chain the 5v power from the pedalboard Arduino (the one with 9v AC power supply and connected to the midi shield) to each of the new keyboard Arduinos...along with grounds and Tx/Rx wiring?

Or do I connect the two new Arduinos to their own 9v power supplies and simply connect ground and Tx/Rx between each?