Mario I. Arguello writes:
>I have a Yamaha RX11 drum machine as well as the famous DX7 keyboard.
>
>I would like to build some dum pads (you know the type with piezo xducers).
>
>Anyone done anything in terms of a drum controller/mixer with PIC chips?


There was an article in  a recent issue of Electronics Today International
(sorry I don't have the issue number) entitled "MIDI Drum Pads" by Tom
Scarff which did exactly what you are requesting. It was implemented using a
PIC16C84. each transducer was connected to a data pin using the following
circuit:

ground -> transducer -> 4k7 resistor -> PIC data pin -> 1k5 resistor ->
ground

When a transducer is struck the data pin goes high. The software scanned the
pins and outputed midi events accordingly - It didn't do velocity though.

Ross.