MIDI CPU Hardware Information

[John]

The new MIDI encoder / MIDI controller product is called the MIDI CPU. The firmware is still being completed, but in the meantime, the hardware user manual and product information can be seen here:

http://highlyliquid.com/midi-controllers/midi-cpu/

[downtownpaulyp]

John,

It'd be great if you could make inputs programmable to be latching, momentary, or pulse. Handy for building things like foot controllers.

[John]

John,

It'd be great if you could make inputs programmable to be latching, momentary, or pulse. Handy for building things like foot controllers.

Yes, the device will be very flexible regarding different types of inputs...footswitch applications will be very easy to implement. Thanks for the suggestion. :)

[str8updrew]

I can't wait for this to come out. I definitely am going to need 3 or 4 of these.

[trixdropd]

This looks like an absolute must purchase for me as well. The products and support you supply John are highly welcomed by me. Thanks a million!!

[jkg]

Yes, the device will be very flexible regarding different types of inputs...footswitch applications will be very easy to implement. Thanks for the suggestion. :)
Hi John,

I have been wanting a custom MIDI trigger device for live stage performance possibly triggered by drum sticks though preferably like a keyboard allowing a held/sustained notes -- though I haven't decided yet.

I'm not really an electronics guy so I'm not even sure what I could do with your products myself, but am intrigued by the MIDI CPU and its possibilities.

I had been considering the purchase of a drum to MIDI trigger, but am assuming (correct me if I am wrong) that those devices have no means to provide a sustained signal for holding a note.

I would like to know a little more about the MIDI CPU.

- Can it interpret a continuous signal for sustained notes (I assume it can)?

- Can you give specific examples of the types of switches needed to allow sustained notes and how velocity sensitivity is factored into switch choices/selection?

- To what extent does your "assembly service" extend if I needed switches attached and the like?

- What else would I need to make such a device a reality? Keep in mind I have only a rudimentary concept in mind of closing a circuit (the trigger) that "magically" gets translated into a MIDI note on/off signal on a certain channel that comes out of your device and into a MIDI sound module. Not knowing all the technicalities, I assume I am missing several steps along the way to building something with your MIDI CPU.

Thanks,
Jim

[John]

Hi Jim,


- Can it interpret a continuous signal for sustained notes (I assume it can)?


Yes.


- Can you give specific examples of the types of switches needed to allow sustained notes and how velocity sensitivity is factored into switch choices/selection?


Any "momentary" switch would work. You could set up the device to send a MIDI note that is sustained as long as the switch is closed...there are other options too.

Velocity for the note can be formed from an analog or digital input separate from the note trigger.


- To what extent does your "assembly service" extend if I needed switches attached and the like?


The MIDI CPU itself is fully assembled, so assembly service will not be necessary. The wiring of additional parts to the MIDI CPU is up to you...but there will be some example "how-to" projects posted. Wiring switches to the MIDI CPU is not difficult...and the forum is here for additional support. :)


- What else would I need to make such a device a reality? Keep in mind I have only a rudimentary concept in mind of closing a circuit (the trigger) that "magically" gets translated into a MIDI note on/off signal on a certain channel that comes out of your device and into a MIDI sound module. Not knowing all the technicalities, I assume I am missing several steps along the way to building something with your MIDI CPU.


Actually, that's pretty much everything you need. :) Did you take a look at the wiring diagrams inside the hardware user manual? Just wire up your switches, add a 9V battery, and go. ;) The other thing you'll need is a MIDI interface on your computer, so that you can send configuration data to the MIDI CPU.

The firmware user manual will be posted soon, which will provide more detail about how everything works. In the meantime, please peruse the hardware user manual, which is already posted on the product page. ;)

[Jim McDougall]

How is the firmware coming ? I have a 32 note pedalboard waiting for this CPU ! Also working out the design of a Mackie Otto like board that could be driven by this.

[gumbo]

Hi John,

My knowledge is also rudimentary - I'm assuming (maybe presuming??) that I could use this unit to accept input from a piezo sensor to produce a midi output.

Would the signal from the piezo need to go via some electronic wizz-bangedry to equate it to a momentary switch, or is this capability within the circuitry of the midi CPU?

I'm looking to take signals from speciality hand percussion stuff (also potentially incorporating switches) and feed them into (sometimes) a roland drum module and (sometimes or also) into other Roland synth stuff...I figure this will be a lot easier and neater if I just "standardise" on using the Midi IN ports on these devices...let alone to get away from the otherwise restrictive nature of the drum module sensor inputs.:eek:

Am I on the right page in looking to your CPU to achieve all of this??

Thank you for such an informative forum.


Regards from springtime Oz.

[Jim McDougall]

Gumbo, as currently described this board will probably not do what you are looking for. The input is switched based and would need an "analog or digital input separately" Not what you need for piezos. It is keyboard oriented as per what John has published about it so far. Check out www.megadrum.info
This is a DIY board that is designed for piezos and drumming and there are kits avaiable.

[gumbo]

Hi Jim, and thanks for that...I have looked around a bit before I got here...but I'll obviously keep looking..
I was drawn to this because I envisage a mixture of piezos AND switches..(I'm not just talking about electronic drums, but custom hand percussion stuff)....and at this early stage of my electronic evolution, I can't see why a signal from a piezo can't be MADE to operate a switch..(and by that, provide the sort of input that the CPU expects)...perhaps I'm not thinking as clearly as I should, but I'd certainly like to investigate this further.

Clearly (at least in my head) this would involve a further link in the chain between 'signal' and CPU, but hey, we mastered brain surgery..:eek:

...any and all responses welcome...:D

...thank you in advance..

[Bongo]

My son (14) and I built a midi marimba, using piezo's glued to the bottom of our wooden slats. Our circuit for converting the signal coming directly off the piezo when the wooden slat is struck is patterned after this:

http://www.musicfromouterspace.com/analogsynth/OLD_SOUNDLABMINISYNTH/drum_trigger_schem.pdf

Hope this helps.

[gumbo]

Thanks Bongo, I'll digest that at the weekend when the work ethic subsides..:D

Most appreciated..

[gumbo]

Yep, got all of that, and yes, I see the point that Bongo is making...

I still would like to get a response from John as to my queries, as I kinda like the look of what is potentially on offer here...

:confused:


...thanks in advance...

[Bongo]

gumbo,

Piezos, for a trigger device that is struck, when paired with a fairly hefty resistor (e.g., 10M ohm), put out an oscillating voltage (i.e., one that goes positive/negative/positive/negative/etc.) and decreases over time. The sample circuit diagram I referenced earlier can be used to produce a single digital on (+5V) and/or a rectified (i.e., all positive) analog control voltage that indicates how hard the trigger device was struck. The former can be used as "logic input" on the midi CPU board (control terminals 0-23). The latter can be used as an "analog input" (control terminals 8-13, 16-23). Depending on whether or not you need both types of signal for your trigger, you could simplify the circuit for one or the other purpose.

Hope this helps.

Bongo

[Bongo]

Any update on expected relase date for MIDI CPU?

[gumbo]

Thanks again Bongo...it's all gradually making more sense:D



I too would like to know more about the projected release date...any news here???

[John]

Hi Everyone, thanks for your interest & discussion. The preliminary firmware manual is now posted--it should shed some light on how everything works.

A firm release date is not available yet--sorry!

[Polyneux74]

Hi Everyone, thanks for your interest & discussion. The preliminary firmware manual is now posted--it should shed some light on how everything works.

A firm release date is not available yet--sorry!

I've downloaded both manuals for the MIDI CPU. I'm super anxious to get one!!
I hate to sound like a broken record but, is the release date any closer now?
(from the whiny kids in the back seat, "are we there yet?") ;)

[gumbo]

Hi John,

any news yet??

Regards from UnderDown! :D

[John]

Update--see:

http://forum.highlyliquid.com/showthread.php?t=189

[John]

Hi John,

My knowledge is also rudimentary - I'm assuming (maybe presuming??) that I could use this unit to accept input from a piezo sensor to produce a midi output.

Would the signal from the piezo need to go via some electronic wizz-bangedry to equate it to a momentary switch, or is this capability within the circuitry of the midi CPU?

I'm looking to take signals from speciality hand percussion stuff (also potentially incorporating switches) and feed them into (sometimes) a roland drum module and (sometimes or also) into other Roland synth stuff...I figure this will be a lot easier and neater if I just "standardise" on using the Midi IN ports on these devices...let alone to get away from the otherwise restrictive nature of the drum module sensor inputs.:eek:

Am I on the right page in looking to your CPU to achieve all of this??

Thank you for such an informative forum.


Regards from springtime Oz.

Yep, got all of that, and yes, I see the point that Bongo is making...

I still would like to get a response from John as to my queries, as I kinda like the look of what is potentially on offer here...

:confused:


...thanks in advance...

Hi Gumbo,

I'll admit that I don't have any experience with piezo triggers (yet). Can you characterize the output signal that they generate? (voltage and pulse duration.)

The MIDI CPU likely would work well with this type of input, but it may requires some sort of "buffer" between the piezo and the input terminal. Let me know if you're still interested in this and we'll start a "piezo to MIDI" thread.

[gumbo]

Hi John...

..a bit slow in getting back here, but yep, still certainly interested in continuing this conversation...I just got involved in other things while I was waiting..:)

Look forward to seeing where this can go...

Regards from Oz!

[John]

Gumbo, as currently described this board will probably not do what you are looking for. The input is switched based and would need an "analog or digital input separately" Not what you need for piezos.

This is not necessarily true. Discussion about using the MIDI CPU with piezo triggers is underway here:

http://forum.highlyliquid.com/showthread.php?t=277