usb parameter control knob / potentiometer

[lanzdona]

I need a little help here...
I am building a foot controlled switching unit for my guitar to use with MainStage.  So far I have mapped the usb controller that I removed from a $5 keyboard, bought 12 x  2" intermittent switches, and am on my way to constructing the pedal board. Everything going as planned.

The problem: I don't understand in what way to connect a parameter control knob / potentiometer to make an expression pedal into the usb.

Happy to finally find a place for DIY music projects!!

Thanks!!

[Digital Larry]

Was there any sort of pot or volume knob on the original keyboard?  I've seen a few that do, in which case you'd simply use the existing circuit.  If there isn't one, you'd need to depend on the chip having some sort of input for a pot and being programmed for it.  I don't know enough to make the latter assumption, but out of curiosity what is the USB chip you are using?

[lanzdona]

Thanks for your response.
It was a usb typing keyboard for a computer.

[Digital Larry]

Perhaps this would be helpful:

http://learn.adafruit.com/downloads/pdf/trinket-usb-volume-knob.pdf

[lanzdona]

Thank you "Digital Larry"!
That looks like something that could easily be adapted.
Plus, the Adafruit Trinket also looks very interesting for other projects!
Thanks,
L