Trying to make it play notes

26 views

Skip to first unread message

FlimsyFlipFlop

unread,

Jun 14, 2025, 12:15:50 PMJun 14

to Mozzi-users

Hello everyone

I've been toying around for a while with Mozzi on a Raspberry Pi Pico H, trying to make cool sounds and synths.

I've been trying to get Mozzi to play notes from a keyboard I've soldered together and connected to the Pico.

I've modified the Mozzi_MIDI_Input example sketch (which I've been succesful in making work in the past) to instead of looking for MIDI notes to change the sine frequency, to have the keyboard be scanned and return MIDI note values internally, and then change the sine's frequency when a note is pressed.

During testing I bypassed the envelope from the example to make sure it doesn't interfere, and also set the frequency in the same way as in the note handler to make sure that's working as well.

In the end the code compiles and uploads, and the sine is outputted, but the frequency doesn't change. I've checked the keyboard scanning function independently, and it works exactly as expected, printing out a single note value, and then 0 when the button is held.

What could be wrong here?

Regard, FFF

#include <Mozzi.h>
#include <mozzi_midi.h>
#include <Oscil.h>
#include <tables/sin2048_int8.h>
#include <ADSR.h>
#include <FixMath.h>

Oscil <SIN2048_NUM_CELLS, MOZZI_AUDIO_RATE> sien(SIN2048_DATA);
ADSR <MOZZI_CONTROL_RATE, MOZZI_AUDIO_RATE> env;

//trying to control the frequency with a keyboard, buttons being active low

uint8_t noten[5][5] = { //Note lookup table (promise it's not rotated, the keyboard's soldered that way)
  {36,41,46,51,56},
  {37,42,47,52,57},
  {38,43,48,53,58},
  {39,44,49,54,59},
  {40,45,50,55,60}
};

bool knopfstati[5][5]; //for button states

uint8_t scan_keyboard() { //in the name
  for (uint8_t links = 0; links < 5; links++) { //go throughthe columns
    for (uint8_t rap = 6; rap < 11; rap++) { //initialize the output lines (colums)
      digitalWrite(rap, HIGH);
    }
    digitalWrite(links+6, LOW); //put the column to be read low
    for (uint8_t rechts = 0; rechts < 5; rechts++) { //read the individual buttons of the row
      bool buttonstate = digitalRead(rechts+1); // offset by 1 because pin 0 is the audio output
      if ((buttonstate == LOW) && (knopfstati[links][rechts] == HIGH)) { //return a note value when a button is pressed
          knopfstati[links][rechts] = buttonstate;
          return noten[links][rechts];
      }
      else if (buttonstate == LOW) { //return 0 if the button is held
        return 0;
      }
      knopfstati[links][rechts] = buttonstate; //always update buttonstate
    }
  }
  return 0xFF; //return 0xFF when nothing is pressed
}

void setup() {
  Serial.begin(115200);
  Serial.println("starting sint...");
  for (uint8_t pinmodeset = 1; pinmodeset < 6; pinmodeset++) { //set pinmodes for rows and columns
    pinMode(pinmodeset, INPUT_PULLUP); //row pins are 1 through 5
    pinMode(pinmodeset + 5, OUTPUT); // column pins are 6 through 10
  }
  //env.setADLevels(127,127); //bypassed
  //env.setTimes(5,5,1000,5);
  sien.setFreq_Q16n16(Q16n16_mtof(Q8n0_to_Q16n16(42))); //testing if audio is being outputted
  startMozzi();
}

void updateControl() {
  uint8_t dus_de = scan_keyboard(); //get the value needed
  if (dus_de != 0xFF && dus_de != 0) { //change frequency if button is pressed
    sien.setFreq_Q16n16(Q16n16_mtof(Q8n0_to_Q16n16(dus_de)));
  }
  //env.update();
}

AudioOutput updateAudio() {
  return MonoOutput::from8Bit(sien.next());
}

void loop() {
  audioHook();
}

Mozzi-users

unread,

Jun 23, 2025, 11:56:40 PMJun 23

to Mozzi-users

Hi,

when you tested scan_keyboard(), was it running in the Mozzi sketch? Just wondering if it has time to complete before being called again...

When I tested here on a different architecture (atmel 328) the sketch worked as expected when I replaced the contents of scan_keyboard() to return a random number.