MIDI Controller

Hi all,

I'm new to Arduino and starting a project which will be an "Isomorphic" MIDI controller.. basically a MIDI keyboard laid out in a hex pattern, with buttons instead of keys. I'm going to place an RGB LED under each button, and record velocity via some DIY force sensitive resistors.

How would I go about reading 100 FSR at once to detect multiple key presses and their pressure values? I'm thinking a shift register may be the solution, but not entirely sure. Since I'm gonna have to poll for that information constantly, it seems like the processor would take a pretty big hit, considering I need to grab the key press within a reasonable amount of time (ideally, faster than a human can distinguish.. <30ms?)

Any help is appreciated.

Not a million miles from my project
http://www.thebox.myzen.co.uk/Hardware/Hexome.html
To read that many force sensors you need an analogue multiplexer.

forst:
I'm new to Arduino and starting a project which will be an "Isomorphic" MIDI controller.. basically a MIDI keyboard laid out in a hex pattern, with buttons instead of keys.

How many, exactly?

It has to be an exact number, 100 is not an option, the first seven orders are:-
1
7
19
37
61
91
127

Grumpy_Mike:
Not a million miles from my project
Hexome
To read that many force sensors you need an analogue multiplexer.

Very cool, this is really similar to what I have in mind. I read all the info you posted and it gave me some ideas. Also interesting how you made the key tops, I had considered that method, but am still trying to figure out a structurally sound way to do it with FSRs. Since I don't need any switches to detect the key press, there's gotta be an elegant way to press down on the FSR with the key top, but also have some kind of resistance/springy feel to it.. I'll figure something out eventually.

fungus:
How many, exactly?

There will be 8 octaves, which is 96 keys total

It is the foam pads round the keys that give it all the tactile springy feel. Force sensors are quite expensive this is going to cost you a lot.
A home made option is to use conducting foam like this other project of mine:-
http://www.thebox.myzen.co.uk/Hardware/MIDI_Footsteps.html

Grumpy_Mike:
It is the foam pads round the keys that give it all the tactile springy feel. Force sensors are quite expensive this is going to cost you a lot.
A home made option is to use conducting foam like this other project of mine:-
MIDI Footsteps

I ended up ordering some Velostat bags and some copper tape to make the FSRs - still waiting for the material to be delivered.
I originally planned on using the conductive foam like you mentioned, but after finding the Velostat material I just assumed it was more accurate in the long run, so wrote off using foam all together.

Now that you mention it, there's nothing stopping me from sandwiching some other type of foam between the key and the FSR.. actually that sounds like a pretty damn good idea. Excited to try some of this stuff out. :slight_smile:

good luck