[sdiy] Keyboard scanner

[GEORGE HEARN]

I'd be interested in this for my polysynth as I've yet to design one for it.  I like AVRs and for 8bit micros I'm a big fan of them.  I'd much rather a system that outputs midi format data over uart though.. I assume this might be more useful for others too.  
  The diode matrix arrangement could be made compatible with FATAR keybeds like the ones from doepffer, and I would also very much like the keboard scanner to have inputs for pitch/mod wheels and also sustain and control pedals...  I guess this isn't quite what you had planned and it amounts to a complete keyboard controller interface, but it would be a great circuit.. the ones doepffer do aren't quite complete.
  The user could interface via MIDI or just direct UART, or you could even add SPI.. having the MIDI standard protocol already in place makes it easy for others to use, and it's all there to be used or ignored.  Thanks George

--- On Tue, 28/7/09, Neil Johnson <neil.johnson97 at ntlworld.com> wrote:

> From: Neil Johnson <neil.johnson97 at ntlworld.com>
> Subject: [sdiy] Keyboard scanner
> To: "synth diy" <synth-diy at dropmix.xs4all.nl>
> Date: Tuesday, 28 July, 2009, 8:58 PM
> Hi all,
> 
> As part of my Siel Opera 6 project I am designing a 61-key
> keyboard scanner module, based on an Atmel ATmega8.  It
> scans all 61 keys via an external 74LS154 decoder and diode
> matrix (already present on the existing contacts board),
> measures the time-of-flight, and works out note-on velocity
> and note-off velocity.  It also handles pitch-bend
> wheel, modulation wheel, expression pedal and sustain pedal
> analogue inputs.  The intention is that it will talk to
> a master processor via SPI (100kbps should be fast enough).
> 
> If this board were to be used for other projects it would
> be useful if the 74LS154 was also on the scanner PCB,
> together with a suitably larger connector (probably 26-pin
> IDC header).  This would necessitate a larger board
> than a dedicated one for my project.
> 
> I figure this project might also be useful to others,
> perhaps those building their own keyboards.  How much
> interest would there be?  If you would find such a
> board useful then please email me off-list and if there is
> enough interest I'll extend the design accordingly.
> 
> Cheers,
> Neil
> --
> http://www.njohnson.co.uk
> 
> 
> 
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