Diode Matrix and MIOS v 1.7

[robinfawell]

Dear Thorsten or anyone else.

I have returned to my SCPOP (Sound Canvas Pipe Organ Project) based design after a few weeks doing other tasks.

I have now stored all the Sysex messages successfully into my Bankstick module and have started producing a table (on paper) with the Sysex file name, the BS No, the Start Offset Address and the length in bytes.

Before starting the next phase - the Button handler for the stops, I would like some advice on two matters.

Diode Matrix

I have wired up one 61 note keyboard (without diodes). This has two DIN Modules at either end. I have built and tested 5 DIN Modules. The Pedal board and the 2nd Keyboard are as yet unwired.  I have calculated that I need 2 core modules. The first will be used for the two keyboards and the second will be used for the pedalboard note inputs (32) and the Stops (revised to about 35) .  I need about another 20 DIN inputs for the Memory Presets to store the Stops and Fader setups. There will be, I'm sure, a few more stops to use with the LCD display.

Is the any advantage, in my case, to reducing the No of Core Modules to one?  Obviously there is a cost implication but I have already incurred this cost.

MIOS Version 1.7

Should I update to the above? (hardware and program)

Regards Robin

[TK.]

Hi Robin,

if the modules are already built, I would suggest the use of one core only for the 8x8 diode matrix (just use the sm_example2, nothing has to be changed), and the other core for the rest. This has the advantage that the button matrix will be scanned under best conditions (lowest latency).

Yes, please update to MIOS V1.7, it always makes sense to use the most recent version (although in this case one hardware change is required: see update info page)

Best Regards, Thorsten.

[John_W._Couvillon]

Robin,

I am just about complete hooking up converting two Moller keyboards for midi, one midio128 with 4 din modules, 61 inputs for the great and 61 for the swell. A second  midio128 will provide for the 32 notes in the pedal and the balance for stops and presets.  Almost complete wiring the swell.  Both work fine with a shorting jumper.  With the merger function implemented,  Jim henry's Miditzer and jorgan work well. Had a bit of a problem with a stuck note, but Thorston and Per s  helped fix that. Boy its just great to have experts to call on!

Cheers,

Johnc

[robinfawell]

Dear John

Its good to hear of your progress. Im in the thick of it trying to design a button handler.

Rgards Robin

[robinfawell]

Dear Thorsten

My keyboards have 61 keys. The switches are formed with a common buss serving 12 keys.  The depression of the key bends a sprung wire to make contact to make a connection to the common buss.  Every contact is gold plated.

The connections required although different to your diagram should be OK .

If convenient the diodes could be mounted on the DOUT modules.

This means that I am unable to use an 8 X 8 scan matrix.

Have you any thoughts?

Regards Robin

[John_W._Couvillon]

Robin,

I went through the same procedure.  Note in the schematics for the DIN modules that you don't need any diodes. The console that I midified has the same common bus for each keyboard. Just isolate it from the power supply and wire from the common bus to the other end of the spring wires.  You don't need diodes. works fine!  I wish that my little spring wires were gold plated. Having problems with poor contacts on some, and can't reach them to clean them.

Johnc

[robinfawell]

Dear John

Your project is about the same as mine.  Before the question about scan matrix and improved latency came up I had decided on two core modules divided in the same way as your configuration.

I cannot relate latency to the organ performance in a practical sense.

I'm not convinced that is so important in my case.

If you or anyone has some comments I will be appreciative.

Regards Robin

[jimhenry]

My keyboards have 61 keys. The switches are formed with a common buss serving 12 keys.  The depression of the key bends a sprung wire to make contact to make a connection to the common buss.  Every contact is gold plated.

Hi Robin. The Switch Matrix should be perfect for your keyboards. I plan to expand Thorsten's example to a 16x32 design to handle my console. Perhaps a 16x16 would be good for you. You would connect each buss to a DOUT pin. You could bring the key contacts in to the DIN pins in groups of 5.

The advantage of putting the diodes at the keyboard end is that you reduce the number of wires that you need between the keyboards and the MIDIbox. If the keys are already cabled, or if there just is no place to put the diodes, you can make a simple diode array to terminate the contact. Here is one of 4 boards I will use in my console:

I already have enhanced the example prepared by Thorsten, in which he did all the hard bits, so that the outputs are set by a table and to provide a display that shows what switch was last closed and what message that sent. For now the table is assembled in rather than being done with a seperately loaded table as in MIDIO128.

If you are ready to start wiring up your keyboards, I'd be happy to work with you to size the switch matrix for your requirements. How many keyboards are you connecting? All based on 12 key busses? Any other inputs?

[robinfawell]

Dear Jim

Thanks for your input.

My system could probably be handled by a 16 X 16 Matrix.

I have 2 keyboards with 61 notes with 5 busses of 12 and 1 buss with 1 note (highest) C?

I have a 32 note pedal board (individual switches, no buss).

Total so far 154

The Console has 51 push buttons associated with Stops including Couplers, Tremelo, Reset.

I have allowed 10 Presets plus 4 controls for Memory.

I estimate to use no more than 10 additional Push Buttons for Controlling the Display

Grand Total 229

If you read my Push Button Handling Thread you will get an idea of the way I hope the button handling is to be achieved.

Do you think that the system musical performance would be better?

One reason for asking is that I have already wired up one manual, with 2 DIN modules  one right and one left of the keys. Using ribbon cable, the wiring seems fairly minimal and neat.

The Pedalboard can be wired using only 1 DIN module.  I have already constructed and tested the DIN modules.

I have plenty of room in the keyboard to mount diodes. However these could alternatively be mounted in the DOUT modules if I adopt the Scan Matrix approach.

Thank you for your interest.

Regards Robin

[jimhenry]

My system could probably be handled by a 16 X 16 Matrix.

Yes, it looks like a good fit to me.

Do you think that the system musical performance would be better?

On an oscilloscope, yes. In what you hear, no. The benefit of the switch matrix is that you only need 1 CORE, 1 DIN, 1 DOUT, and 1 LCD. It will probably be easier to maintain. Figure no cost advantage because you already have the hardware either way, but with switch matrix you have spares. You'll have to decide if you want to redo the one keyboard or press forward with the original plan. Either should work quite well. If you want to change to a switch matrix let me know and I'll sketch a proposal for the wiring for your consideration.

I have plenty of room in the keyboard to mount diodes. However these could alternatively be mounted in the DOUT modules if I adopt the Scan Matrix approach.

If I understand what you are thinking, no you can't put the diodes on the DOUT board. You need one diode per switch contact in the circuit that connects a DOUT line to a DIN line through the switch. The picture of the bottom of the keyboard that Thorsten connected shown in the Diode Matrix Input topic shows this pretty clearly:

http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=midification;action=display;num=1088098331

[robinfawell]

Dear Jim

I am going to postpone the decision about whether to use a scan matrix or not.  I know that both solutions will work.

My main problem at present is the button handler.  This is proving very difficult for me due to my ignorance of MIOS and lack of assembler programming ability

But thanks for your kind offer.

Diode Placement

If you draw a diagram showing Thorsten's circuit . You will see that between the  DOUT terminals (C0 - C7)  and the common buss there is a switch and then a diode.  In my suggestion there is a diode followed by a switch.

It does not really matter.

Regards Robin

[jimhenry]

If you draw a diagram showing Thorsten's circuit . You will see that between the  DOUT terminals (C0 - C7)  and the common buss there is a switch and then a diode.  In my suggestion there is a diode followed by a switch.

True. But you still need one diode per switch. The main thing is to figure out what is the best place to put them to minimize the effort of making the connections.

My main problem at present is the button handler.

See my comments in that thread. Maybe you are trying to solve the wrong problem with the buttons.