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Old 01-28-2016, 06:17 AM
Richard Richard is offline
Junior Member
Join Date: Feb 2014
Posts: 10
Question Swell Pedal Code Help


I wondered if you could help me. I have a 25 note Conn pedal board that I installed a Midi 3 controller in and the pedals work fine. I've included a listing of the code I used for reference and perhaps it will help someone else. Now, I am trying to connect a swell pedal (also from a Conn organ). To get something working, I am just using a 10k pot not mounted in the pedal. I can not get the AtoD converted to work. I have searched the forums but only find snippets of code but nothing that has helped. In one position of the pot the Midi CPU sends out a value but it's always the same. All of my pins above ct15 are free. I have connected the wiper of the pot to ct16 and the ends of the pot to the reference pins on the MIDI CPU.

For the life of me I can not insert code that makes the pot cause the Midi CPU to output a message when the pot's wiper changes position. I see examples for outputing a constant stream of notes but all I want is a volume control. My firmware is 1.2a. I tried updating to 1.4 beta but nothing would work at all with that firmware installed. I was able to reload 1.2a and at least got back to where I began. I tried this twice and got the same results each time. I suspect I am missing some key concept. I don't understand if I have to put in upper and lower range limits and how to use the registers. I was dropped on my head when I was a kid so please forgive me if these questions have been answered. I would like to know what do I have to add to my code to accept an analog input on ct16. Nothing I have tried comes close to working.

Thanx Richard

//Using a 4x8 matrix
F0 00 01 5D 04 01 00
//Data Lines
00 00 7F 00 00 00
00 01 7F 00 00 00
01 00 7F 00 00 00
01 01 7F 00 00 00
02 00 7F 00 00 00
02 01 7F 00 00 00
03 00 7F 00 00 00
03 01 7F 00 00 00
04 00 7F 00 00 00
04 01 7F 00 00 00
05 00 7F 00 00 00
05 01 7F 00 00 00
06 00 7F 00 00 00
06 01 7F 00 00 00
07 00 7F 00 00 00
07 01 7F 00 00 00
//Control Lines
08 00 2C 00 24 00
08 01 7F 00 00 00
09 00 2C 00 2C 00
09 01 7F 00 00 00
0A 00 2C 00 34 00
0A 01 7F 00 00 00
0B 00 2C 00 3C 00
0B 01 7F 00 00 00
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Old 01-28-2016, 11:21 PM
Richard Richard is offline
Junior Member
Join Date: Feb 2014
Posts: 10
Default Here is a little more info about my Swell pedal project

I upgraded the firmware to 1.3 Beta 4 since 1.4 Beta 4 didn't work at all. This version did not work either. I uploaded the newer version 1.3 Beta 4 and it seemed to load ok. The Led went out after the send. When I rebooted the Midi CPU, I tried sending the sequence in the instructions. The light did not flash and nothing worked at all. I reloaded 1.2a and it's back to working. I suspect there may be something wrong with the Midi CPU because no matter what code I send to modify the unused CT's above 15, nothing changes. They still act like a switch even with a pot connected. There is one position that will send key down and key up messages but always the same message.

I am using all eight data bits in the switch matrix. Does that not allow an Analog input because there are no available data inputs?

Since this Midi CPU will not work with newer firmware and I get nowhere trying different configurations for the higher pins, is this a lost cause. Am I just spinning my wheels?

I works ok for my original purpose as a Pedal Midi Interface.

I considered using a Arduino as a Analog to Digital converted which I know how to do and feeding it into the Midi CPU as an encoder input but is that do-able?

Thank you in advance for any advice you can give me.

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Old 01-29-2016, 07:01 PM
Richard Richard is offline
Junior Member
Join Date: Feb 2014
Posts: 10
Default How I added contacts to Conn Organ Pedals..

Perhaps someone considering converting a Conn 25 note pedal board to Midi will find these pictures useful. The organ was a Conn 640 Theater organ (with vacuum tubes. I am using the lower half of the console for my Virtual Pipe Organ. The top and bottom halves are screwed and glued together. I took out the screws and pried the two halves apart with a big screwdriver from the back. They came apart without doing too much damage to the case. Next, I tool the pedal mechanism out of the bottom of the case. It had lotsa useless parts and vacuum tubes which I removed. The original contacts may have been enough to make this work but they were 50 years old and didn't look good. My first attempt to add new contacts were using magnetic reed switches and magnets mounted on each pedal lever. There is so much steel inside the assembly that it didn't work to well. I had to use some powerful magnets and they would sometimes cause neighboring reed switches to close too. I scraped that idea and went to small micro switches I bought from china. This approach seems to be working well. As long as the switches hold up, this should do the trick.

Here are some pictures....

#1 Empty Conn console lower half Up-Side-Down
#2 Original Electonics
#3 Micro Switches and Midi CPU installed
#4 A hold down strip installed to keep the switches from moving (made form window stop molding)

Hope this is useful to someone...

Attached Images

Last edited by Richard; 01-29-2016 at 07:09 PM. Reason: Rewording
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Old 02-13-2016, 03:59 PM
Synthetech's Avatar
Synthetech Synthetech is offline
Join Date: May 2012
Location: USA
Posts: 711

Hi Richard,

Sorry I did not see this earlier.. if you are still needing help, perhaps I can assist.

First, when you said-

I have connected the wiper of the pot to ct16 and the ends of the pot to the reference pins on the MIDI CPU.
what "reference pins" are you talking about?
you should be using the Vreg terminals from the MIDI CPU.

what code are you trying to use to get a CT to use a potentiometer?
are you using the Analog Registers chart at the beginning of the manual to find and insert the proper register for the CT you are using in the code?

I am certain your MIDI CPU can upgrade to 1.4 since it seems to work for other updates.. perhaps there is an operation error we can uncover.

Let me know if you would like to try and get it working and I'll try to help.
It will help if you can get a Configuration Dump for your CPU. Check the end of the manual on how to get a Dump for your Layer 00h.

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analog input code, potentiometer input, swell pedal

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