Connecting a custom MIDI Ribbon Synth to the Axoloti, and other interfacing questions

#1

I recently undertook a project and want to incorporate my Axoloti into the final product. I followed this tutorial 1-for-1 on building a MIDI Ribbon Synth from an arduino: http://www.coagula.org/content/pages/how-build-midi-ribbon-controller-arduino

Basically, it sends pitch info from MIDI CC 20, and Velocity from CC 21 (it needs to be mapped manually).

I know stuff like filters can have custom CC's, but what would I use in place of the midi/in/keb mod object for pitch and velocity? Would midi/in/cc work? and even then, how would I send velocity or a note/off signal?

And onto more custom CC's:

What is the best way to go about physically adding switches, buttons, faders and potentiometers etc to the Axoloti? Would you recommend doing it all on a separate breadboard?

One more question:

if I wanted to power the axoloti externally, what is the best way to do this? I'm using a 9V for my Arduino, will that work as well?

#2

bump would really appreciate help, I cannot seem to find a working solution for this.

#3

i think it would be much easier to edit the arduino code to output note on and off...

#4

Converting the ribbon into MIDI via an Arduino is possible, but I'd recommend skipping the Arduino and using the analog GPIO inputs of Axoloti. MIDI will only reach around 500 measurements a second when using two MIDI CC's, and only have 128 steps, while the gpio analog inputs on Axoloti will do 3000 measurements a second with 4096 steps. That will feel quite a bit more "analog".
You can follow the same schematic that you linked to, just substitute 5V to VDDC, A0 to PA0, A1 to PA1.
To read the voltages, use the gpio/in/analog object.

My favorite option is a USB powerbank connected to the mico-usb socket.
To power from 9V you need to use the DC input (barrel) socket, or if you prefer, you can also solder wires to the solder pads ("X2") next to the DC input socket, this needs 7V minimum.

#5

use midi/in/cc ... for pitch , you will need to covert to a bipolar (conv/unipolar2bipolar), then you can send to an oscillator

you say CC 21 is velocity, are you sure its not pressure? in which case if its 'quick' enough, you could just feed this into a vca , i.e. you control the amplitude with pressure.
converting to a velocity, would mean taking multiple reading over a time, and then using the difference between the first (>0) and the last ... (ok, reality is, tuning velocity is very much down to the sensor, as it depends how quickly it reacts etc)..
for example a really simple example, is to take the pressure as it goes over zero, wait one control cycle, then take that pressure, take the difference, then send that as velocity, and create a gate.

honestly, though, I think your better 'playing the envelope' than trying to generate a velocity/gate... thats more designed for switches :slight_smile: (keyboards)

other controls... im a beginner at that, but im mocking up on a breadboard first, but will then mount them into a 'panel', then take wires back to a board, which will have header pins that I then connect to header pins on the axoloti.... but Im sure others will be be able to give much better suggestions.

#6

If I was running the soft potentiometers into the Axoloti, I wouldn't need the MIDI connector anymore, would I? My goal is just to have these potentiometers control a synth sound on the Axoloti.

#7

yes exactly, and you could even use the axoloti to still get midi out, and possibly control other synths, if you like at a later point...

#8

is there any way for me to test within the board if the potentiometers are successfully sending a signal? i'm new to this, and do a lot by guess and check.

#9

Create a gpio/in/analog object in (any) patch, then, in the object popup menu, choose "help". That patch will show all activity on all analog inputs after checking "live".

#10

ahh sorry figured it out, forgot to read that part of your original post! i used a disp/chart p, and needless to say i'm pretty blown away that it took 10 hours of labor for the arduino, and less than 5 minutes for the axoloti :wink:

#11

Sorry, one more question: I've added a few dials to the Axoloti, how can I have them directly affect a dial on an object? For example, my fx/chorus's mix?

EDIT: FIXED BY CONVERTING THE SIGNAL TO MIDI CC.

I'm now hooking up a switch, how can I have it switch between two things in a phi/ctrl/i radio 3 v?

EDIT: FIXED THAT TOO. FOR THOSE WHO ARE CURIOUS, USE CONV/TO B