[LAU] Open Source MIDI control surface

David Griffith dgriffi at cs.csubak.edu
Tue Dec 2 16:54:10 EST 2008

On Tue, 2 Dec 2008, Matthew Smith wrote:

> Hi Tim
> > interesting thread as i am working on a control-surface myself atm ... i
> > would be curious, if someone has some experience with higher-precision
> > adc? most io boards i know (arduino/makingthings) provide 10-bit adcs,
> > while i'd be interested in getting a higher resolution ... does anyone
> > have experience with interfacing a microcontroller (e.g. arduino) with an
> > external high-resolution adc?
> For regular 7-bit stuff, I'll be using a 16-input, 8-bit ADC.  However,
> in order to get higher resolutions for the 2 x 7-bit messages, I am
> dropping analogue input in favour of rotary encoders.
> The encoders that I will be using (currently on their way from China)
> output a 2-bit Gray code, meaning that I can read 4 of them
> simultaneously using a single port.  (I'll actually be using 8 in a 4 x
> 2 matrix, scanning them just like a keypad.)  $16 USD for 10 - quite a
> lot cheaper than pots!
> If your input has to be analogue, ADCs are available with many different
> interfaces - synchronous serial (like the TI ones I'll be using), SPI,
> I2C and byte-wide, which can be accessed like external memory.

I'm surprised nobody has mentioned midibox.org yet.  They have everything
you need to make your own control surface, and it's all GPLed.  There are
links there about midifying pipe organs and assorted other things.  One
guy turned a sofa into a midi controller.

David Griffith
dgriffi at cs.csubak.edu

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