jimhenry

Have you looked inside your keyboard? Do you know if the keys are wired with a diode matrix? The MIDIIO128 project is the most likely choice for MIDIfying a keyboard. The easiest way to use it is to have up to 128 switch closures that generate MIDI messages as you define in a table. You will need a core board and 1 DIN board for each 32 switch inputs. There is an experimental project for using a diode matrix switch. It probably is pretty close to usable for what you want to do but documentation and support will be minimal. For this you need the core board, 1 DIN board, and 1 DOUT board. If you want to build your own boards, you actually only need 1 DIN chip and 1 DOUT chip for 64 inputs.

I don't know if there is anyone here who knows USB-MIDI deeply enough to advise you. If you don't mind gutting the keyboard it would probably be a surer path to success to simply replace the existing keyboard electronics with a MIDIbox. Trying to take advantage of the USB interface looks like an uphill battle to me. Trying to add any additional controls to use the existing electronics sounds particularly difficult.

If you have a +5V logic supply on the analog console that can source a few hundred milliamps for the MIDIbox, it would probably be better to run the MIDIbox on the same power as the analog console. Hopefully Smash will smash in here as he is a much better source of advice on these types of things than I am. But if you do run separate power for the MIDIbox, it is that power that Smash was suggesting putting the caps on to get a very low noise power supply.

Confirmed on it's OK to use MIDIIO128 with only DOUT or only DIN. SmashTV's latest version of DOUT board allows the use of driver chips as an alternative to the current limiting resistors. You might be able to use those instead of relays or they will at least simplify driving the relays if needed.

It sounds like you were being modest in your original post. The newest version of SmashTV's DOUT board can use driver chips rather than current limiting resistors. Perhaps you can find chips that will allow you to deliver the higher voltage you need to drive the tone generators.

Analog organ circuits are all over the map. It is possible that there is an audio signal being switched by the keys. If it is DC, it is impossible to say what that signal feeds into and whether the minute pullup current on a DIN would upset the balance of the circuit. It might well be an easy thing to do and it might not. Unless you have the circuit diagram and you can evaluate the effect of adding the DIN circuit to an existing analog circuit, you just don't know.

My suggestion would be to radically midify the Wurlitzer 950 first as that appears like it will be an easier project. Once you have that under your belt you will be in a much better position with regard to the other organ. If you want to proceed now with the other organ, I would still suggest only providing MIDI Out. I don't dispute your reasons for wanting to add MIDI In but your self assessed electronic skills don't seem up to the challenge. You need to understand the analog electronics to be able to add MIDI In. The safest way to add the MIDI Out would be to add a set of contacts for every switch and key that is to be MIDIfied to keep the MIDIbox electronics completely separate from the original organ electronics. It might not be necessary but you'll need to understand the analog electronics to know if you can borrow the signals for the purposes of MIDIfying the console. Building a MIDIbox as a standalone project is not too hard. When you start modifying the circuits of an analog organ you are now reengineering the organ. That is a big step up from merely building a MIDIbox. I hate to rain on your parade but I don't want you in over your head on an organ you are trying to preserve.

Go to the DokuWIKI http://wiki.midibox.org/ via the button at the top of the Forum page. Look for the entry on where to get parts and kits. Building a core and a DIN and experimenting with them on the bench will teach you more in a week than you can learn with a year of reading. Be sure to include an LCD display, at least in your first project.

On the DIN side a simple resistive voltage divider can lower the voltage BUT it might upset the analog circuits in the organ. DOUT is more complicated because you need to know what is needed in terms of both voltage and current. Further, there might be issues of noise being introduced into the analog audio circuits. Before you get too far into this you need to ask yourself why you want to preserve the original organ sound and why you want to use DOUT. These days you can get an organ sound that is probably far superior to what an analog electronic organ produces. Are you holding on to the analog circuits for any reason beyond a sense that you shouldn't discard that much circuitry? I've been wrestling with the issue for years with my Rodgers Trio organ, a high end electronic of its time. Other projects have kept me from doing anything with the Trio but I have decided that when I get back to it I'm stripping out the analog electronics as not worth the extra complications to making the console into a MIDI controller. Once you discard the analog electronics, DOUT would be pointless with nothing to control. But if you retain the analog electronics, why do you want to control them with MIDI? The only reason I can think of is so you can use a sequencer to drive the analog tone generation. Do you really have analog tone generation that is so good and so unique that it is worth the effort to drive it with MIDI?

The MIDIIO128 project is the one to use for converting keyswitch closures to MIDI messages. You'll need a Core and 2 DIN boards for your 61 keys. It is probably easiest to add new contacts under the keys for the MIDIbox rather than trying to find a signal that you can use without upsetting the KCII unless you are pretty savvy about what is going on inside the KCII.

For organ projects where one needs to deal with a lot of inputs only or a lot of outputs only, would it make sense to take MIDIIO128 as a starting point and create an application that does just input or just output? I am trying to make a guess as to why there is a 128 input or output limit. Is it the practical limit on the length of the serial shift chain? The limit of available memory for the configuration tables? A perceived limit because of 128 MIDI values? Just arbitrary based on the needs of the project that gave rise to MIDIIO128? What I am thinking is that both of the serial pins could be used for input or for output and one of the two configuration tables replaced by a second input or output table to service the second serial shift chain. Is this sensible? Or should I just use 2 linked cores for every 256 inputs or outputs and not worry about trying to squeeze more into an input only or output only configuration? What I am think of initially is just an "extension cord" to take about 500 wires from an organ console, convert them to MIDI, run them to the organ chamber via MIDI over fiber optics, and then convert them back to 500 wires. Ultimately I might enhance the deserialization end to convert the MIDI In to the 1000 or so wires needed for the pipes.

To answer my own question, I think it is not so hard although I haven't looked at the code yet. Consider what the MIDIIO128 does with MIDI Input. It looks for an entry with the same MIDI command and the same MIDI channel number and sets an output pin on or off. It may consider what a parameter value is to decide on or off. The channel number part of the table is 4 bits for 16 channels, not enough to support the 128 MIDI instruments, which would require 7 bits. So you add a 16 byte channel table in the synth, one byte per MIDI channel. Each byte holds a 7 bit instrument number. When you receive a MIDI message you use the MIDI channel as an index into the channel table to look up your instrument number. The MIDIIO output table has to be made bigger with a 7 bit instrument number replacing the 4 bit channel. Now you look for an entry with the same instrument number as you obtained by look up rather than the same channel number. The only other change is that MIDIIO128 has to process program change as a message directed to the synth engine and not for generating an output. Program change simply writes the instrument number into the appropriate byte of the channel table.

Does anyone have a sense of how big an effort it would be to extend MIDIIO128 to operate as a MIDI driven synthesizer with support for Program Change and Channels? What I mean is that I would like to identify a range of outputs as belonging to a MIDI insteument (0-127). I would then like to be able to send a Program Change on a MIDI Channel selecting a MIDI Instrument. Thereafter the MIDIbox would take the MIDI messages and direct them to the appropriate output pins based on the MIDI channel.

Agreed about needing to get some documentation about this branch of MidiBoxes into the Wiki. Check out this proud owner and his MidiBox: There is nothing in that console but MidiBoxes and maybe audio amplifiers. Some Miditzer users are working on a box that converts three expression controllers to MIDI. This will be a good starter project because it only uses a core board.

The Miditzer has always output MIDI. A long time ago the channels were fixed but they have been configurable for quite awhile. If your pipes are driven by MIDI then the Miditzer could drive them.

I love the new look! ;D And the tabs to jump right to the WIKI or the uCapps pages is a big help. BRAVO!!

I think you can also solve the switched pins on the core board by using a cable that twists the 5 and 6 wires: Mind you I haven't tried this. I haven't even ever built an IDC cable with a twist. But if I was going to, I'd split my flat cable between 4 and 5 and between 6 and 7 for about 3 inches. Then I'd twist the 5-6 pair 180 degrees. Then I'd tape the flat cable on both sides of where I was going to add the IDC connector so that I had all the wires firmly held where they belong. I'd be extra careful when making the crimp to be sure the all the wires were lining up correctly with the insulation displacement forks in the connector.

The Miditzer is also capable of being used without the computer screen, mouse, or computer keyboard. It is just less aparent since the Miditzer is designed to make it very easy for a new user to get started and so it presents those interfaces as something everyone will have. You can also drive any output device you want including MIDI controlled pipes. Again less obvious because the Miditzer tries to be sure everyone will hear something without effort. I believe jOrgan now has a way to tie a rank to a specific MIDI channel which is needed for real pipe control but that has always been inherent in the Miditzer.

SmashTV is doing a design upgrade to all the boards used in the various MIDIbox projects, primarily to ease construction and to provide more connector options. I've seen a sneak preview of some of these improvements. It will be well worth the wait for the new design. I'm told it will be "a couple of weeks." It's a major effort, so I counsel patience. For MIDIbox, I'm far from being a guru. The Miditzer question should be reposted on the Miditzer Forum, www.VirtualOrgan.com/forum/.

Yes, you are headed in the right direction as far as MIDIbox goes. As to trying to repair the Yamaha, you may be better off just biting the bullet and scrapping all the electronics. MIDIbox wants simple switch inputs. Trying to uses the console switches (keys) to control both the existing tone generators and the MIDIbox adds a layer of complexity. You probably would be better off using 2 DINs on one core for one manual and 3 DINS on the other for the other manual plus pedals to balance the processing load. For 1 expression input you will not need the AIN. You can go directly into the core. When you get to that point, we can dig up the particulars.

Are you looking for something like these found in the MIOS Download area? sm_example1_v2.zip 41k How to drive a button matrix of 8x8 = 64 buttons. See also this connection diagram. Additional examples, e.g. for 1024 buttons scanned by a single core module, are planned once this driver has been tested in a real environment. sm_example2_v1.zip 43k How to handle a button matrix of 8x8 = 64 buttons superfast (within 80 uS) and with debouncing. I've done some further development of those examples but I haven't yet expanded beyond an 8x8 matrix.

What sort of help do you need? The MIDIIO128 project was original for Midifying a band organ. DOUT boards will produce a digital on/off signal in response to MIDI messages of your choosing. You'll need to provide some additional circuitry between the DOUT and the pipe magnets to handle the electrical load. There is some documentation, a schematic as I recall, of a way to connect a DOUT to relays on Thorsten's site. That will give you some ideas. You need to think about whether a standard MIDI cable is going to be fast enough to deliver all the data a pipe organ will consume on the output side of the virtual relay. I think some "cleverness" will be required in this regard. Maybe it will be as simple as using a multiport USB to MIDI interface box and then running MIDI cables to multiple Midibox cores, each core controlling 1 or 2 ranks of up to 128 pipes. I wouldn't suggest using the core linking feature for this application.

I have no idea.

MIDIO128 is the project you'll want to use for both projects as your type of project is exactly what MIDIO128 was done for in the first place. MIDIO64 is directed more toward making a MIDI control surface including potentiometer inputs. Take some time to poke around. There are lots of interesting and useful things to be found including the story of the original MIDIO128 project and recommendations for LCD displays.

I think it would be appropriate for Thorsten to politely but firmly point out to the seller that the MIDI Box code is NOT licensed for use in commercial project.