Multiple COREs, shared ground? shared MIDI?

MIDIfication
1

Hi,

I’ve spent some time in the forum and in SmashTV site, and came out with more questions than answers.

I don’t want to fry a CORE if I make a mistake.

As said before, I have the project of MIDIfying a 3 keyboard / pedalboard / 68 stop switches + a number of buttons old analog organ console. I plan to use MIDIO128 for its ease of usage, and thus 3 CORES, 10 DINS, 3 DOUTS for later LED feedback on the stops.

I’m wondering if I can? may? must? connect together the ground line of all DIN chains.

Each keyboard has 61 keys, and I would like to “optimize” the usage of contacts in MIDIO128, since I’ll have 3 spare contacts per pair of DINS : map the first keys of each “subsequent” keyboard on the last free pins of the “previous” keyboard DIN pair. That would allow me to “save” the last 9 pins of the last keyboard DIN and use them for stop or preset control.

I imagine that a shared ground would enable me to achieve this.

I’m also wondering about the MIDI connectors.

I plan to interconnect all CORES though J11 and activate the MIDI forwarding in order to have a MIDI chain with a single MIDI-In and a single MIDI-Out.

Is is possible/allowed to set the full MIDI interface on the “slave” boards, just to be able to connect each one to the computer, one at a time, when and only when I need to upload / update the application ?

For normal operation, the MIDI connectors would be unconnected.

Last unanswered question:

I was led to believe that, on the SmashTV CORE, all I need to use to connect the DIN chain is a 5-pin SIL connector (I don’t want to solder wires to the pins). True ? False ?

And I believe that the same holds true if I want to connect a DIN chain AND a DOUT chain to the same CORE.

Many thanks for your patience about newbie questions.

2

I’m wondering if I can? may? must? connect together the ground line of all DIN chains.

There is only one ground and hence all grounds must be connected.

Is is possible/allowed to set the full MIDI interface on the “slave” boards, just to be able to connect each one to the computer, one at a time, when and only when I need to upload / update the application ?

Yes. You can mount all parts (maybe except for the midi sockets you don’t need) and connect those out -> in to the next core module.

I was led to believe that, on the SmashTV CORE, all I need to use to connect the DIN chain is a 5-pin SIL connector (I don’t want to solder wires to the pins). True ? False ?

Correct. You can also use a 2x5 and simply chain all DIN and DOUT modules taht are hooked up to a single core in one line.

3

Hi,

I’ve spent some time in the forum and in SmashTV site, and came out with more questions than answers.

I don’t want to fry a CORE if I make a mistake.

Very hard to fry a Core but still a good idea to ask questions before proving me wrong about that.

As said before, I have the project of MIDIfying a 3 keyboard / pedalboard / 68 stop switches + a number of buttons old analog organ console. I plan to use MIDIO128 for its ease of usage, and thus 3 CORES, 10 DINS, 3 DOUTS for later LED feedback on the stops.

I think you only need 9 DINS (9x32 = 288 inputs). 3x61 + 32 + 68 = 283 but maybe you have more than 5 buttons (pistons)? Also you should have at least one spare DIN and a spare Core if the budget allows for a project of this size.

I’m wondering if I can? may? must? connect together the ground line of all DIN chains.

I’ll second nILS on tying all grounds together.

Each keyboard has 61 keys, and I would like to “optimize” the usage of contacts in MIDIO128, since I’ll have 3 spare contacts per pair of DINS : map the first keys of each “subsequent” keyboard on the last free pins of the “previous” keyboard DIN pair. That would allow me to “save” the last 9 pins of the last keyboard DIN and use them for stop or preset control.

I imagine that a shared ground would enable me to achieve this.

I think the “optimization” of packing all the keyboards is a poor idea. Start each keyboard at the same place on a DIN board. It will pay big dividends in maintaining your sanity. It doesn’t really matter where anything is connected. You can make any input do anything via the configuration table. Use the disjointed spare pins for pistons or stops (pistons are more useful) as you wish. Dealing with 9 scattered pins is no big deal. Dealing with 183 keyboard inputs that are not highly consistent is a nightmare.

I’m also wondering about the MIDI connectors.

I plan to interconnect all CORES though J11 and activate the MIDI forwarding in order to have a MIDI chain with a single MIDI-In and a single MIDI-Out.

Is is possible/allowed to set the full MIDI interface on the “slave” boards, just to be able to connect each one to the computer, one at a time, when and only when I need to upload / update the application ?

For normal operation, the MIDI connectors would be unconnected.

I recommend using the MIDI connectors and NOT using J11. The reports I have seen from people doing multi-core organ Midifications is that daisy chaining the Core MIDI connections and enabling the MIDIIO128 MIDI Merge is the easier way to go. If each PIC has a unique ID, you can program them while they are connected in a daisy chain.

I recommend adding the PCB mount MIDI connectors (no longer included in the Smash Core kit). DIN sockets are better mechanical connections than SIL connectors. Even you are going to use panel mount MIDI sockets, I recommend using half of a MIDI cable to connect the panel socket to the Core MIDI socket. This also makes it easier to work with a bare Core board if the need arises.

Last unanswered question:

I was led to believe that, on the SmashTV CORE, all I need to use to connect the DIN chain is a 5-pin SIL connector (I don’t want to solder wires to the pins). True ? False ?

While only 5 pins are absolutely necessary, Smash provides 10 pin DIL connectors. Use 10 pin IDC connectors on ribbon cable to interconnect the boards. DIL connectors are better mechanically than SIL connectors.

And I believe that the same holds true if I want to connect a DIN chain AND a DOUT chain to the same CORE.

As of R4 DOUT and R5 DIN, Smash has set up the DIN and DOUT boards so they can be freely intermixed in one chain using the 10 pin connectors.

4

I think the “optimization” of packing all the keyboards is a poor idea. Start each keyboard at the same place on a DIN board. It will pay big dividends in maintaining your sanity. It doesn’t really matter where anything is connected. You can make any input do anything via the configuration table. Use the disjointed spare pins for pistons or stops (pistons are more useful) as you wish. Dealing with 9 scattered pins is no big deal. Dealing with 183 keyboard inputs that are not highly consistent is a nightmare.

Occured to me also after sleeping on it :).

I recommend using the MIDI connectors and NOT using J11.

Why is J11 so bad ?

And can I make my own short MIDI cables to connect MIDI-Out to the next MIDI-In ?

If yes, which kind of cable should I use ?

Edit: Oh, I think I found out : shielded twisted pair should do the trick

I recommend using half of a MIDI cable to connect the panel socket to the Core MIDI socket

Do you mean a regular male DIN plug at the CORE end and the panel mount socket at the “outer world” end ?

5

Why is J11 so bad ?

I wouldn’t say J11 is bad. Bear in mind I have never set up a multi-core system myself. I just recall seeing posts from people who were doing it and having trouble configuring a J11 chain. When they switched to a MIDI chain they got everything working right away. If you use a MIDI chain then everything is according to MIDI standard. The MIDI Out of each board is just what you’d expect. MIDI In is merged with the MIDI generated at that Core. You can use all your MIDI troubleshooting knowledge to deal with any issues, either Core by Core or anywhere in the chain. Plus I’m really big on good mechanical connections and the DIN 5 connector used for MIDI is very good mechanically. Chosen to stand up to the abuse of stage performances. :slight_smile:

And can I make my own short MIDI cables to connect MIDI-Out to the next MIDI-In ?

If yes, which kind of cable should I use ?

Edit: Oh, I think I found out : shielded twisted pair should do the trick

Of course you can make your own MIDI cables. But you’ll probably get a better cable for less money buying premade if you can. Hosa makes 1 foot MIDI cables. Third party seller Brook Mays has them for $2.31 on US Amazon: # ASIN: B000068NTK # Item model number: MID301BK

Do you mean a regular male DIN plug at the CORE end and the panel mount socket at the “outer world” end ?

Exactly. My point is spend a buck and add the PCB mount female DIN socket on the Core and use a male DIN plug rather than the 3 pin SIL connector. I’ve had nothing but trouble with broken connections to the 3 pin SIL. BTW, if you have an old XT/AT keyboard, you can probably scavenge a cable with a 5 pin male DIN plug at one end from it. Otherwise, buy a long premade MIDI cable, cut it in half, and add your female DIN panel sockets to the cut ends. You probably want 2 cables for DIN and DOUT so you can program the Cores with a panel connection.

6

What’s wrong with just soldering the wires from one board to another?

7

Inevitably you are going to need to do something where you need to remove a board. PCBs aren’t made to withstand repeated soldering and unsoldering.

With all due respect, if you have these kinds of questions, you should start with a less ambitious project. I am pretty sure that the #1 reason for failure of MidiBox projects is overambition. You are going to learn a lot in getting your first MidiBox up and running. Your second MidiBox will be a lot better. I think you will be a lot happier if the big project is your second project.

8

What’s wrong with just soldering the wires from one board to another?

Yeah, like he said..

Testing and troubleshooting are a big part of the project. And the easiest way to get it right

is to first test your PC MIDI interface, then test two standard MIDI cables, then you can test

and program each core individually, with the fair assumption that your interface and cables are good.

It is well worth the cost of connectors to do this right.

LyleHaze