[LAU] Open Source MIDI control surface

Matthew Smith matt at smiffytech.com
Mon Dec 1 16:41:08 EST 2008

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.



Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
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