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Old 03-19-2013, 06:56 PM
theFlaneur theFlaneur is offline
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Default MIDI CPU to drive Crosspoint Matrix (not a keyboard switch matrix)

Hello,

I'm somewhere in between novice and intermediate as far as electronics goes, so please pardon my ignorance. I'm hoping someone could offer some advice on how I can use the MIDI CPU to interface an IC that is an 8x8 analog signal routing matrix

I found someone online who made essentially the same thing, only his version can only interface with a computer running specific software via USB. I want the MIDI CPU to drive it. Here's his project. Essentially it's a dual 8x8 signal routing matrix - within each matrix any input can be assigned to any output, and any combination therein.

He's using these ICs and interfacing them with an Arduino-like microcontroller called a Teensy 2.0. He even goes into great detail on how he programmed the Teensy to interface with the ICs here.

My project is straightforward:

I have approximately 96 combinations of 8 inputs I want to route in series, parallel, etc. all combined into a single output. I'd like the MIDI CPU to output MIDI commands (notes, CCs... doesn't matter) to another PCB with these 96 combinations stored as presets, recalling the routing of the ICs per preset.

Presets would be selected via rotary encoder connected to the CPU.

That's it! The need for the MIDI CPU to be the brains of this project is that the entire thing needs to be incredibly space-efficient and self-contained. No need to hookup to an external CPU except for programming, etc.

Any ideas?

Many thanks in advance for your help!!
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Old 03-19-2013, 09:40 PM
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John John is offline
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Quote:
Originally Posted by theFlaneur View Post
Hello,

I'm somewhere in between novice and intermediate as far as electronics goes, so please pardon my ignorance. I'm hoping someone could offer some advice on how I can use the MIDI CPU to interface an IC that is an 8x8 analog signal routing matrix

I found someone online who made essentially the same thing, only his version can only interface with a computer running specific software via USB. I want the MIDI CPU to drive it. Here's his project. Essentially it's a dual 8x8 signal routing matrix - within each matrix any input can be assigned to any output, and any combination therein.

He's using these ICs and interfacing them with an Arduino-like microcontroller called a Teensy 2.0. He even goes into great detail on how he programmed the Teensy to interface with the ICs here.

My project is straightforward:

I have approximately 96 combinations of 8 inputs I want to route in series, parallel, etc. all combined into a single output. I'd like the MIDI CPU to output MIDI commands (notes, CCs... doesn't matter) to another PCB with these 96 combinations stored as presets, recalling the routing of the ICs per preset.

Presets would be selected via rotary encoder connected to the CPU.

That's it! The need for the MIDI CPU to be the brains of this project is that the entire thing needs to be incredibly space-efficient and self-contained. No need to hookup to an external CPU except for programming, etc.

Any ideas?

Many thanks in advance for your help!!
Hi theFlaneur,

The MSA-R (or MSA-P) has 8 on/off outputs whose on/off states can be stored to and recalled from up to 128 presets.

Are 8 on/off outputs enough to control the signal routing electronics in this project? (If not, multiple MSA units can be chained together and will respond as one unit. There is also the MD24 with 24 outputs.)

Let me know, and we can work out the details. Sending the preset messages from the MIDI CPU and setting up the MSA will be a piece of cake...
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Old 03-19-2013, 09:52 PM
theFlaneur theFlaneur is offline
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Originally Posted by John View Post
Hi theFlaneur,

The MSA-R (or MSA-P) has 8 on/off outputs whose on/off states can be stored to and recalled from up to 128 presets.

Are 8 on/off outputs enough to control the signal routing electronics in this project? (If not, multiple MSA units can be chained together and will respond as one unit. There is also the MD24 with 24 outputs.)

Let me know, and we can work out the details. Sending the preset messages from the MIDI CPU and setting up the MSA will be a piece of cake...
Thanks John --

Funny you mention it, I've actually already worked out a scheme to do this with a MIDI CPU and a pair of MSA-Rs... but in my research I stumbled upon this guy's routing matrix and thought perhaps I could do it with one less PCB. Also, the MSA-R version ends up leaving 3 relays empty on each board because of the specifics of the scheme.

Basically, I have 2 sets of 4 wires: black, red, white, green/ground. The catch is that certain combinations require connecting the signals from some wires to each other.

For example, one preset would be black, red+white, green/ground; then black and green/ground terminate at external output and ground point, respectively.

Another would be black+red, white+green/ground, then each of those terminate at an external output and ground, respectively.

I can achieve this on the MSA-R using jumpers across different in/out terminals but a routing matrix would simplify this a lot.

Hope that makes sense.

That said, I *do* have a solution with the MSA-R, just wanted to see if I can up the 'elegance' factor with a separate routing matrix PCB.

thanks!
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Old 03-22-2013, 01:28 PM
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To change the state of one of the 128 switches on the MT8816, you have to "point to" that switch with a 7-bit address, and then use the "data" pin to set the switch to on or off. So if you wanted to set a pattern of on/off states for each preset, some microcontroller programming would be required.

It sounds like your existing plan is the best way to do this without employing something like the MT8816 and doing some microcontroller programming.

I suppose that the details of your signal routing requirements will determine the easiest way to accomplish things using two MSA units.

If you do end up using the MSAs, I hope you'll share your project over in the MSA forum.
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