The Oakley midiDAC midi to CV convertor module
The midiDAC is a single channel midi to analogue convertor. This project is a joint
development between Oakley Sound and Trevor Page. Trevor wrote the firmware for the
processor used in this project.
The midiDAC is designed to drive any 1V/octave synthesiser or modular system. There are
eight outputs available:
Gate:
+5V gate
Pitch CV:
127 steps of 12 bit accurate pitch voltage conforming to 1V/octave
(trimmable). Pitch bend is added to this signal and the maximum bend
interval (up to one octave) can be adjusted from the bend depth control.
Velocity:
0 to 10V proportional to midi note on velocity.
Pitch Bend:
-5V to +5V proportional to pitch bend wheel position. 0V corresponds to a
centred wheel.
Modulation:
0 to 10V proportional to modulation wheel position.
Aftertouch:
0 to 10V proportional to midi channel aftertouch.
CC # 100:
0 to 10V proportional to midi controller number 100.
Legato:
This signal goes to +5V when two notes are played at the same time. This
can allow slides to be activated at will; TB303 style. An optional external
switch may be used to override the automatic activation of slide. Slide may be
turned off by transmitting the standard midi glide/slide command.
Also featured on the circuit board itself is a 3-way header to directly feed the Oakley ‘CV-
gate’ bus on the Dizzy board.
The design also features a midi thru circuit which is greatly improved on the previous issue
midiDAC designs. The processor used in this project is a
PIC16F628
running at
4 MHz
.
Please note: this product does not support the use of V/Hz or linear VCOs. These are found
on some Yamaha and Korg analogue products, and just one Roland, the SH-2000.
4
