halogravity
Well-known member
Hello everyone. Recently I started building a basic synth for my young niece, so obviously bright blinky lights were a big factor. 
I started creating my own pcb and used Cherry MX keyboard keys. Then multiplexing came into play, and it began to get a little complicated(being my first PCB design). I then stumbled upon the Keybow 2040 (https://shop.pimoroni.com/products/keybow-2040?variant=32399559589971) which is quite literally exactly what I was going for in my design(16 hot-swappable MX keys, addressable LED's, etc). I decided to try using the Teensy as a host and plug the Keybow into the Teensy. I loaded up the MidiSynthKeyboard sketch and SUCCESS! Almost! The lights light up and the notes play, but I dont think its reading the notes from the Teensy sketch, The Keybow uses the Raspberry Pi 2040 chip, and is the code is written in circuit python. Here is the sketch for the keybow:
It came with the Keybow 2040 code as an example and works great as a midi controller. There is even an arpeggiator and a 4 track sequencer (Thanks Sandy!) Here's my issue. The way the MidiSynthKeyboard sketch is written the mixer number is a variable, "TOTAL_MIXERS", so with my limited knowledge of the audio system I am having trouble loading it into the Audio Design tool.
Basically, how do I add effects onto the audio chain? When I try and paste the code to the Audio design tool I get a few boxes and no connections, and I'm a bit confused. I feel like maybe starting from scratch would be better, because honestly I'd rather use oscillators like in a virtual analog setup rather than wavetables anyway but then I don't know how to get the Teensy to read the notes the Keybow sends polyphonically and this setup seems so close to what I need.
And lastly, is there a way to setup a button or pot to scroll through the different wavetables? The keybow has the ability to hold a key and press another (like a shift/function key) but I cant figure out what determines the wavetable used by the synth. Is it the channel the Keyboard is transmitting Midi on? And I have SUPER limited CircuitPython knowledge.
And just to make it slightly more complex Id like to add an encoder that would change the key and scale the keyboard is playing. The click of the encoder would change the key and the turn would change through scales (Major, Minor, Mixolydian, Dorian, etc.)
I'm sorry to throw so much out there I am just feel like I'm so close and I'm hoping someone out there can point me in the right direction. Can I make the MidiSynthKeyboard sketch work or should I start from scratch?
Thanks in advance for any help you guys can provide! I appreciate you taking the time reading this. Here is the MidiSynthKeyboard sketch for reference. The patch section is whats throwing me and seems to throw the audio tool as well. I just would like to add some reverb, maybe chorus and delay, the usual stuff.
I started creating my own pcb and used Cherry MX keyboard keys. Then multiplexing came into play, and it began to get a little complicated(being my first PCB design). I then stumbled upon the Keybow 2040 (https://shop.pimoroni.com/products/keybow-2040?variant=32399559589971) which is quite literally exactly what I was going for in my design(16 hot-swappable MX keys, addressable LED's, etc). I decided to try using the Teensy as a host and plug the Keybow into the Teensy. I loaded up the MidiSynthKeyboard sketch and SUCCESS! Almost! The lights light up and the notes play, but I dont think its reading the notes from the Teensy sketch, The Keybow uses the Raspberry Pi 2040 chip, and is the code is written in circuit python. Here is the sketch for the keybow:
Code:
# SPDX-FileCopyrightText: 2021 Sandy Macdonald
#
# SPDX-License-Identifier: MIT
# Demonstrates how to send MIDI notes by attaching handler functions to key
# presses with decorators.
# You'll need to connect Keybow 2040 to a computer running a DAW like Ableton,
# or other software synth, or to a hardware synth that accepts USB MIDI.
# Drop the `keybow2040.py` file and `keybow_hardware` folder
# into your `lib` folder on your `CIRCUITPY` drive.
# NOTE! Requires the adafruit_midi CircuitPython library also!
import time
from keybow2040 import Keybow2040
from keybow_hardware.pim56x import PIM56X as Hardware # for Keybow 2040
#from keybow_hardware.pim551 import PIM551 as Hardware # for Pico RGB Keypad Base
import usb_midi
import adafruit_midi
from adafruit_midi.note_off import NoteOff
from adafruit_midi.note_on import NoteOn
# Set up Keybow
keybow = Keybow2040(Hardware())
keys = keybow.keys
# Set USB MIDI up on channel 0.
midi = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=0)
# The colour to set the keys when pressed.
rgb = (0, 255, 50)
# Initial values for MIDI note and velocity.
start_note = 36
velocity = 127
# Loop through keys and attach decorators.
for key in keys:
# If pressed, send a MIDI note on command and light key.
@keybow.on_press(key)
def press_handler(key):
note = start_note + key.number
key.set_led(*rgb)
midi.send(NoteOn(note, velocity))
# If released, send a MIDI note off command and turn off LED.
@keybow.on_release(key)
def release_handler(key):
note = start_note + key.number
key.set_led(0, 0, 0)
midi.send(NoteOff(note, 0))
while True:
# Always remember to call keybow.update()!
keybow.update()It came with the Keybow 2040 code as an example and works great as a midi controller. There is even an arpeggiator and a 4 track sequencer (Thanks Sandy!) Here's my issue. The way the MidiSynthKeyboard sketch is written the mixer number is a variable, "TOTAL_MIXERS", so with my limited knowledge of the audio system I am having trouble loading it into the Audio Design tool.
Basically, how do I add effects onto the audio chain? When I try and paste the code to the Audio design tool I get a few boxes and no connections, and I'm a bit confused. I feel like maybe starting from scratch would be better, because honestly I'd rather use oscillators like in a virtual analog setup rather than wavetables anyway but then I don't know how to get the Teensy to read the notes the Keybow sends polyphonically and this setup seems so close to what I need.
And lastly, is there a way to setup a button or pot to scroll through the different wavetables? The keybow has the ability to hold a key and press another (like a shift/function key) but I cant figure out what determines the wavetable used by the synth. Is it the channel the Keyboard is transmitting Midi on? And I have SUPER limited CircuitPython knowledge.
And just to make it slightly more complex Id like to add an encoder that would change the key and scale the keyboard is playing. The click of the encoder would change the key and the turn would change through scales (Major, Minor, Mixolydian, Dorian, etc.)
I'm sorry to throw so much out there I am just feel like I'm so close and I'm hoping someone out there can point me in the right direction. Can I make the MidiSynthKeyboard sketch work or should I start from scratch?
Thanks in advance for any help you guys can provide! I appreciate you taking the time reading this. Here is the MidiSynthKeyboard sketch for reference. The patch section is whats throwing me and seems to throw the audio tool as well. I just would like to add some reverb, maybe chorus and delay, the usual stuff.
Code:
/* Play notes with a regular USB MIDI Instrument.
To use this example, connect a USB instrument to Teensy 3.6's
USB host port. This cable is recommended:
https://www.pjrc.com/store/cable_usb_host_t36.html
Requires Teensy 3.6 for USB host capability.
Requires Audio Shield: https://www.pjrc.com/store/teensy3_audio.html
*/
#include "Pizzicato_samples.h"
#include "FrenchHorns_samples.h"
#include "Viola_samples.h"
#include "BasicFlute1_samples.h"
#include "Ocarina_samples.h"
#include <Bounce.h>
#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>
#include <USBHost_t36.h>
//#define DEBUG_ALLOC
const int TOTAL_VOICES = 64;
const int TOTAL_MIXERS = 21;
const int SECONDARY_MIXERS = 4;
USBHost myusb;
USBHub hub1(myusb);
USBHub hub2(myusb);
USBHub hub3(myusb);
KeyboardController keyboard1(myusb);
KeyboardController keyboard2(myusb);
MIDIDevice midi1(myusb);
AudioControlSGTL5000 sgtl5000_1;
AudioSynthWavetable wavetable[TOTAL_VOICES];
AudioMixer4 mixer[TOTAL_MIXERS];
AudioOutputI2S i2s1;
AudioConnection patchCord[] = {
{wavetable[0], 0, mixer[0], 0}, {wavetable[1], 0, mixer[0], 1}, {wavetable[2], 0, mixer[0], 2}, {wavetable[3], 0, mixer[0], 3}, {mixer[0], 0, mixer[TOTAL_MIXERS - 2], 0},
{wavetable[4], 0, mixer[1], 0}, {wavetable[5], 0, mixer[1], 1}, {wavetable[6], 0, mixer[1], 2}, {wavetable[7], 0, mixer[1], 3}, {mixer[1], 0, mixer[TOTAL_MIXERS - 2], 1},
{wavetable[8], 0, mixer[2], 0}, {wavetable[9], 0, mixer[2], 1}, {wavetable[10], 0, mixer[2], 2}, {wavetable[11], 0, mixer[2], 3}, {mixer[2], 0, mixer[TOTAL_MIXERS - 2], 2},
{wavetable[12], 0, mixer[3], 0}, {wavetable[13], 0, mixer[3], 1}, {wavetable[14], 0, mixer[3], 2}, {wavetable[15], 0, mixer[3], 3}, {mixer[3], 0, mixer[TOTAL_MIXERS - 2], 3},
{wavetable[16], 0, mixer[4], 0}, {wavetable[17], 0, mixer[4], 1}, {wavetable[18], 0, mixer[4], 2}, {wavetable[19], 0, mixer[4], 3}, {mixer[4], 0, mixer[TOTAL_MIXERS - 3], 0},
{wavetable[20], 0, mixer[5], 0}, {wavetable[21], 0, mixer[5], 1}, {wavetable[22], 0, mixer[5], 2}, {wavetable[23], 0, mixer[5], 3}, {mixer[5], 0, mixer[TOTAL_MIXERS - 3], 1},
{wavetable[24], 0, mixer[6], 0}, {wavetable[25], 0, mixer[6], 1}, {wavetable[26], 0, mixer[6], 2}, {wavetable[27], 0, mixer[6], 3}, {mixer[6], 0, mixer[TOTAL_MIXERS - 3], 2},
{wavetable[28], 0, mixer[7], 0}, {wavetable[29], 0, mixer[7], 1}, {wavetable[30], 0, mixer[7], 2}, {wavetable[31], 0, mixer[7], 3}, {mixer[7], 0, mixer[TOTAL_MIXERS - 3], 3},
{wavetable[32], 0, mixer[8], 0}, {wavetable[33], 0, mixer[8], 1}, {wavetable[34], 0, mixer[8], 2}, {wavetable[35], 0, mixer[8], 3}, {mixer[8], 0, mixer[TOTAL_MIXERS - 4], 0},
{wavetable[36], 0, mixer[9], 0}, {wavetable[37], 0, mixer[9], 1}, {wavetable[38], 0, mixer[9], 2}, {wavetable[39], 0, mixer[9], 3}, {mixer[9], 0, mixer[TOTAL_MIXERS - 4], 1},
{wavetable[40], 0, mixer[10], 0}, {wavetable[41], 0, mixer[10], 1}, {wavetable[42], 0, mixer[10], 2}, {wavetable[43], 0, mixer[10], 3}, {mixer[10], 0, mixer[TOTAL_MIXERS - 4], 2},
{wavetable[44], 0, mixer[11], 0}, {wavetable[45], 0, mixer[11], 1}, {wavetable[46], 0, mixer[11], 2}, {wavetable[47], 0, mixer[11], 3}, {mixer[11], 0, mixer[TOTAL_MIXERS - 4], 3},
{wavetable[48], 0, mixer[12], 0}, {wavetable[49], 0, mixer[12], 1}, {wavetable[50], 0, mixer[12], 2}, {wavetable[51], 0, mixer[12], 3}, {mixer[12], 0, mixer[TOTAL_MIXERS - 5], 0},
{wavetable[52], 0, mixer[13], 0}, {wavetable[53], 0, mixer[13], 1}, {wavetable[54], 0, mixer[13], 2}, {wavetable[55], 0, mixer[13], 3}, {mixer[13], 0, mixer[TOTAL_MIXERS - 5], 1},
{wavetable[56], 0, mixer[14], 0}, {wavetable[57], 0, mixer[14], 1}, {wavetable[58], 0, mixer[14], 2}, {wavetable[59], 0, mixer[14], 3}, {mixer[14], 0, mixer[TOTAL_MIXERS - 5], 2},
{wavetable[60], 0, mixer[15], 0}, {wavetable[61], 0, mixer[15], 1}, {wavetable[62], 0, mixer[15], 2}, {wavetable[63], 0, mixer[15], 3}, {mixer[15], 0, mixer[TOTAL_MIXERS - 5], 3},
{mixer[TOTAL_MIXERS - 2], 0, mixer[TOTAL_MIXERS - 1], 0},
{mixer[TOTAL_MIXERS - 3], 0, mixer[TOTAL_MIXERS - 1], 1},
{mixer[TOTAL_MIXERS - 4], 0, mixer[TOTAL_MIXERS - 1], 2},
{mixer[TOTAL_MIXERS - 5], 0, mixer[TOTAL_MIXERS - 1], 3},
{mixer[TOTAL_MIXERS - 1], 0, i2s1, 0},
{mixer[TOTAL_MIXERS - 1], 0, i2s1, 1},
};
Bounce buttons[] = { {0, 15}, {1, 15}, {2, 15}, };
const int TOTAL_BUTTONS = sizeof(buttons) / sizeof(Bounce);
void guitarHeroMode();
void printVoices();
void setVolume() {
sgtl5000_1.volume(0.8*(analogRead(PIN_A2) - 1) / 1022.0);
}
struct voice_t {
int wavetable_id;
byte channel;
byte note;
};
voice_t voices[TOTAL_VOICES];
IntervalTimer midiMapTimer;
IntervalTimer guitarHeroTimer;
IntervalTimer volumeTimer;
void setup() {
Serial.begin(115200);
pinMode(0, INPUT_PULLUP);
pinMode(1, INPUT_PULLUP);
pinMode(2, INPUT_PULLUP);
AudioMemory(120);
sgtl5000_1.enable();
sgtl5000_1.volume(0.8);
for (int i = 0; i < TOTAL_VOICES; ++i) {
wavetable[i].setInstrument(Pizzicato);
wavetable[i].amplitude(1);
voices[i].wavetable_id = i;
voices[i].channel = voices[i].note = 0xFF;
}
for (int i = 0; i < TOTAL_MIXERS - 1; ++i)
for (int j = 0; j < 4; ++j)
mixer[i].gain(j, 0.50);
for (int i = 0; i < 4; ++i)
mixer[TOTAL_MIXERS - 1].gain(i, i < SECONDARY_MIXERS ? 1.0 / SECONDARY_MIXERS : 0.0);
Serial.println("USB Host Testing");
myusb.begin();
keyboard1.attachPress(OnPress);
keyboard2.attachPress(OnPress);
midi1.setHandleNoteOff(OnNoteOff);
midi1.setHandleNoteOn(OnNoteOn);
midi1.setHandleControlChange(OnControlChange);
//volumeTimer.begin(setVolume, 100000);
guitarHeroTimer.begin(guitarHeroMode, 1000000 / 120);
//midiMapTimer.begin(printVoices, 5000);
delay(2000);
}
void loop() {
myusb.Task();
midi1.read();
//for (int i = 0; i < TOTAL_BUTTONS; ++i) buttons[i].update();
//if (buttons[0].fallingEdge()) AudioSynthWavetable::print_performance();
//if (buttons[1].risingEdge()) {
// midiMapTimer.end();
// Serial.print('\n');
//}
//if (buttons[1].fallingEdge()) midiMapTimer.begin(printVoices, 5000);
//if (buttons[2].risingEdge()) guitarHeroTimer.end();
//if (buttons[2].fallingEdge())
// guitarHeroTimer.begin(guitarHeroMode, 1000000/60);
}
int allocateVoice(byte channel, byte note);
int findVoice(byte channel, byte note);
void freeVoices();
int used_voices = 0;
int stopped_voices = 0;
int evict_voice = 0;
int notes_played = 0;
void OnPress(int key)
{
Serial.print("key '");
Serial.print((char)key);
Serial.print("' ");
Serial.println(key);
//Serial.print("key ");
//Serial.print((char)keyboard1.getKey());
//Serial.print(" ");
//Serial.print((char)keyboard2.getKey());
//Serial.println();
}
void OnControlChange(byte channel, byte control, byte value)
{
Serial.print("Control Change, ch=");
Serial.print(channel);
Serial.print(", control=");
Serial.print(control);
Serial.print(", value=");
Serial.print(value);
Serial.println();
}
void OnNoteOn(byte channel, byte note, byte velocity) {
notes_played++;
#ifdef DEBUG_ALLOC
//Serial.printf("**** NoteOn: channel==%hhu,note==%hhu ****\n", channel, note);
printVoices();
#endif //DEBUG_ALLOC
freeVoices();
int wavetable_id = allocateVoice(channel, note);
switch (channel) {
case 1:
wavetable[wavetable_id].setInstrument(BasicFlute1);
break;
case 2:
wavetable[wavetable_id].setInstrument(FrenchHorns);
break;
case 3:
wavetable[wavetable_id].setInstrument(Ocarina);
break;
case 4:
wavetable[wavetable_id].setInstrument(Ocarina);
break;
case 5:
wavetable[wavetable_id].setInstrument(Pizzicato);
break;
default:
wavetable[wavetable_id].setInstrument(Pizzicato);
break;
}
wavetable[wavetable_id].playNote(note, velocity);
#ifdef DEBUG_ALLOC
printVoices();
#endif //DEBUG_ALLOC
}
void OnNoteOff(byte channel, byte note, byte velocity) {
#ifdef DEBUG_ALLOC
//Serial.printf("\n**** NoteOff: channel==%hhu,note==%hhu ****", channel, note);
printVoices();
#endif //DEBUG_ALLOC
int wavetable_id = findVoice(channel, note);
if (wavetable_id != TOTAL_VOICES)
wavetable[wavetable_id].stop();
#ifdef DEBUG_ALLOC
printVoices();
#endif //DEBUG_ALLOC
}
int allocateVoice(byte channel, byte note) {
int i;
int nonfree_voices = stopped_voices + used_voices;
if (nonfree_voices < TOTAL_VOICES) {
for (i = nonfree_voices; i < TOTAL_VOICES && voices[i].channel != channel; ++i);
if (i < TOTAL_VOICES) {
voice_t temp = voices[i];
voices[i] = voices[nonfree_voices];
voices[nonfree_voices] = temp;
}
i = nonfree_voices;
used_voices++;
}
else {
if (stopped_voices) {
i = evict_voice % stopped_voices;
voice_t temp = voices[i];
stopped_voices--;
voices[i] = voices[stopped_voices];
voices[stopped_voices] = temp;
used_voices++;
i = stopped_voices;
}
else
i = evict_voice;
}
voices[i].channel = channel;
voices[i].note = note;
evict_voice++;
evict_voice %= TOTAL_VOICES;
return voices[i].wavetable_id;
}
int findVoice(byte channel, byte note) {
int i;
//find match
int nonfree_voices = stopped_voices + used_voices;
for (i = stopped_voices; i < nonfree_voices && !(voices[i].channel == channel && voices[i].note == note); ++i);
//return TOTAL_VOICES if no match
if (i == (nonfree_voices)) return TOTAL_VOICES;
voice_t temp = voices[i];
voices[i] = voices[stopped_voices];
voices[stopped_voices] = temp;
--used_voices;
return voices[stopped_voices++].wavetable_id;
}
void freeVoices() {
for (int i = 0; i < stopped_voices; i++)
if (wavetable[voices[i].wavetable_id].isPlaying() == false) {
voice_t temp = voices[i];
--stopped_voices;
voices[i] = voices[stopped_voices];
int nonfree_voices = stopped_voices + used_voices;
voices[stopped_voices] = voices[nonfree_voices];
voices[nonfree_voices] = temp;
}
}
void guitarHeroMode() { // now unicorn friendly
const int RESET = 4;
const int MIDI_NOTES = 128;
static char line[MIDI_NOTES + 1] = { 0 };
static int accumulated = 0;
if (!accumulated) {
for (int i = 0; i < MIDI_NOTES; ++i) line[i] = '-';
++accumulated;
}
for (int i = stopped_voices; i < used_voices + stopped_voices; ++i) line[voices[i].note] = '*';
if (accumulated++ == RESET) {
Serial.println(line);
accumulated = 0;
}
}
const char* note_map[] = {
"C","C#","D","D#","E","F","F#","G","G#","A","A#","B"
};
void printVoices() {
static int last_notes_played = notes_played;
if (last_notes_played == notes_played)
return;
last_notes_played = notes_played;
int usage = AudioProcessorUsage();
Serial.printf("\nCPU:%03i voices:%02i CPU/Voice:%02i evict:%02i", usage, used_voices, usage / used_voices, evict_voice);
for (int i = 0; i < used_voices; ++i)
Serial.printf(" %02hhu %-2s", voices[i].channel, note_map[voices[i].note % 12]);
}
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