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  #1  
Old 10-29-2013, 11:38 AM
Hackemoff Hackemoff is offline
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Default Matrix keyboard on an Octave Cat SRM

Im about to MIDIfy my Octave Cat SRM with a MIDI-CPU and a CV/Gate converter, mostly due to a damaged keyboard circuitry. So now I need to connect the j-wires of the Cats keyboard in a switch matrix.

I guess the most simple way to do this is to split the upper j-wire bar in two and use them as Select lines, and cut the resistor for each key and put wires from two of each j-wire to the MIDI-CPU as Data lines.

So this will be a 2x19 matrix as this regards a 37-note keyboard. Will this idea work? Can I skip diodes, since it only will be played monophonically?


Have you thought anything about my earlier suggestion on monophonic output from the MIDI-CPU? (http://forum.highlyliquid.com/showth...?t=1011&page=2) Because it will very much come in handy here as well!
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  #2  
Old 11-02-2013, 02:13 PM
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The MIDI CPU can support a matrix with up to 8 data lines. So 2 select x 19 data would not work, but if you really wanted to, you could make a 19 select x 2 data matrix.

That's a pretty inefficient use of MIDI CPU control terminals, however. (21 total.) If you rearranged the matrix into, say, 5 select x 8 data, you'd only be using 13 control terminals.

Unfortunately, for now, enforcing monophonic MIDI note output is still outside of the scope of the MIDI CPU firmware, sorry.
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  #3  
Old 11-04-2013, 08:31 AM
Hackemoff Hackemoff is offline
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Yes, it is inefficient, but I dont feel comfortable splitting the j-wire busbar in many pieces. And since Im not gonna use any terminals for other functions, I think this is the easiest way to make it work for me.

But for a 19x2 solution I will need to use both the j-wire busbars, one for each "pair" of notes. Unfortunately the lower busbar looks quite bad, but Ill try to fix it. Please take a look at the attached config file.


What can you say regarding the use of diodes in this case?
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File Type: txt Cat.txt (537 Bytes, 119 views)

Last edited by Hackemoff; 11-05-2013 at 09:10 AM.
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  #4  
Old 11-21-2013, 12:11 PM
Hackemoff Hackemoff is offline
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Default Please reply

Please reply to my questions, so I can start building...
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  #5  
Old 11-21-2013, 04:04 PM
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Quote:
Originally Posted by Hackemoff View Post
Yes, it is inefficient, but I dont feel comfortable splitting the j-wire busbar in many pieces. And since Im not gonna use any terminals for other functions, I think this is the easiest way to make it work for me.

But for a 19x2 solution I will need to use both the j-wire busbars, one for each "pair" of notes. Unfortunately the lower busbar looks quite bad, but Ill try to fix it. Please take a look at the attached config file.
It looks good to me. Nice work! I did find one issue:

CT #19 can't be used for matrix select output. So you should skip Ct #19 and use CT 21 instead.

Quote:
What can you say regarding the use of diodes in this case?
Diodes are not required. However, if you include them, they will prevent "aliasing" from occurring when certain combinations of switches are simultaneously closed.
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Old 10-15-2015, 09:15 PM
Hackemoff Hackemoff is offline
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OK. So now I finally revived this project.

And after soldering all 37 key connectors two-by-two to MIDI-CPU terminals #2->#21 (not using #19), and one j-wire busbar each to #0 and #1, I programmed it with a modified config (leaving out #19).

But now strange things are happening! The activity LED keeps blinking irregularly. Nothing happens when any of the keys are pressed. MIDI-Out snapshot shows as below:

B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 00
B1 78 7F
B3 78 7F
B5 78 7F
B5 78 00
...

MIDI-Thru works fine though, allowing me to play the synth via the attached MIDI-CV interface.

I tried to update the firmware to 1.4beta but it did not help. What have gone wrong here?
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Old 10-26-2015, 02:10 AM
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Quote:
Originally Posted by Hackemoff View Post
OK. So now I finally revived this project.

And after soldering all 37 key connectors two-by-two to MIDI-CPU terminals #2->#21 (not using #19), and one j-wire busbar each to #0 and #1, I programmed it with a modified config (leaving out #19).

But now strange things are happening! The activity LED keeps blinking irregularly. Nothing happens when any of the keys are pressed. MIDI-Out snapshot shows as below:

B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 78
B5 7F 78
B5 78 7F
B5 78 00
B1 78 7F
B3 78 7F
B5 78 7F
B5 78 00
...

MIDI-Thru works fine though, allowing me to play the synth via the attached MIDI-CV interface.

I tried to update the firmware to 1.4beta but it did not help. What have gone wrong here?
If you can post a config dump, it might help to reveal the problem.
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Old 10-26-2015, 06:30 AM
Hackemoff Hackemoff is offline
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Quote:
Originally Posted by John View Post
If you can post a config dump, it might help to reveal the problem.
OK. Here it is: (just a small modification, skipping CT#19 from the old one above):


// Header
F0 00 01 5D 04 01

// CT 0-1: Matrix data
00 00 7F 00 00 00
00 01 7F 00 00 00
01 00 7F 00 00 00
01 01 7F 00 00 00

// CT 2-20: Matrix select
02 00 2C 05 30 0D
03 00 2C 05 32 0D
04 00 2C 05 34 0D
05 00 2C 05 36 0D
06 00 2C 05 38 0D
07 00 2C 05 3A 0D
08 00 2C 05 3C 0D
09 00 2C 05 3E 0D
0A 00 2C 05 40 0D
0B 00 2C 05 42 0D
0C 00 2C 05 44 0D
0D 00 2C 05 46 0D
0E 00 2C 05 48 0D
0F 00 2C 05 4A 0D
10 00 2C 05 4C 0D
11 00 2C 05 4E 0D
12 00 2C 05 50 0D
14 00 2C 05 52 0D
15 00 2C 05 54 0D

// Footer
F7
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Old 10-28-2015, 06:30 AM
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Can you post a config dump generated by the MIDI CPU itself?

In other words, send this to the MIDI CPU:

F0 00 01 5D 04 00 7F 00 F7

...and then post what it sends back.

Quote:
Originally Posted by Hackemoff View Post
OK. Here it is: (just a small modification, skipping CT#19 from the old one above):


// Header
F0 00 01 5D 04 01

// CT 0-1: Matrix data
00 00 7F 00 00 00
00 01 7F 00 00 00
01 00 7F 00 00 00
01 01 7F 00 00 00

// CT 2-20: Matrix select
02 00 2C 05 30 0D
03 00 2C 05 32 0D
04 00 2C 05 34 0D
05 00 2C 05 36 0D
06 00 2C 05 38 0D
07 00 2C 05 3A 0D
08 00 2C 05 3C 0D
09 00 2C 05 3E 0D
0A 00 2C 05 40 0D
0B 00 2C 05 42 0D
0C 00 2C 05 44 0D
0D 00 2C 05 46 0D
0E 00 2C 05 48 0D
0F 00 2C 05 4A 0D
10 00 2C 05 4C 0D
11 00 2C 05 4E 0D
12 00 2C 05 50 0D
14 00 2C 05 52 0D
15 00 2C 05 54 0D

// Footer
F7
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