What is it?

This programmable guitar pedal is your sandbox for creating new sounds and altering the sounds of your instrument. Armed with the Teensy 4.1, this pedal has an absurd amount of processing power for you to work with. The Teensy outperforms virtually all microcontrollers on the market, and excels at audio tasks, including FFTs, digital effects, and sound synthesis. Paired with the WM8960 audio codec, it is ready to generate endless high-quality sounds, and apply limitless digital effects to your instrument.

This pedal is designed for insertion into a 1590B enclosure, so you're all set when you're ready to make your design look professional.

What makes it special?

This device is convenient and well-priced such that you can implement whatever sound alteration you can imagine.

Use the highly flexible Teensy Audio Library to build the exact sound you imagine. PJRC provides an online GUI for you to build effects in, check it out here: https://www.pjrc.com/teensy/gui/ This guitar pedal is designed to work perfectly with the PJRC Audio System Design tool, so your development can go smoothly.

This board is designed with audio quality in mind - expect perfect audio.

Specifications

Designed for enclosure: 1590B (not included - for now)

• Length: 111.9mm
• Width: 60.9mm
• Depth: 31.6mm, including back plate

Audio chipset: WM8960

• DAC SNR 98dB (‘A’ weighted), THD -84dB at 48kHz, 3.3V
• ADC SNR 94dB (‘A’ weighted), THD -82dB at 48kHz, 3.3V
• Pop and click suppression
• 70dB PSRR @217Hz
• Pseudo differential for high noise immunity
• Sample rates (kHz): 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48
• 24-bit stereo 64x oversampled sigma-delta ADCs

Board includes:

• 3x potentiometers
• 1x LED
• 1x foot switch
• Audio input and output (of course)
• Barrel jack input (5v to 20v input)
• 9v battery connector
• Automatic switch over to barrel jack when available
• Automatically turns off if input jack is not connected

Example code

Bitcrusher Pedal:

#include 
#include 
#include 
#include 
#include

// GUItool: begin automatically generated code
AudioInputI2S2           i2s2_input1;     //xy=608,249
AudioEffectBitcrusher    bitcrusher1;    //xy=844,290
AudioEffectBitcrusher    bitcrusher2;    //xy=854,400
AudioMixer4              mixer_left;     //xy=1013,364
AudioMixer4              mixer_right;    //xy=1018,498
AudioOutputI2S2          i2s2_output1;    //xy=1204,429
AudioConnection          patchCord1(i2s2_input1, 0, mixer_left, 0);
AudioConnection          patchCord2(i2s2_input1, 0, bitcrusher1, 0);
AudioConnection          patchCord3(i2s2_input1, 1, mixer_right, 0);
AudioConnection          patchCord4(i2s2_input1, 1, bitcrusher2, 0);
AudioConnection          patchCord5(bitcrusher1, 0, mixer_left, 1);
AudioConnection          patchCord6(bitcrusher2, 0, mixer_right, 1);
AudioConnection          patchCord7(mixer_left, 0, i2s2_output1, 0);
AudioConnection          patchCord8(mixer_right, 0, i2s2_output1, 1);
// GUItool: end automatically generated code


#define POT1 14
#define POT2 15
#define POT3 16
#define FOOTSWITCH 40
#define LED 29


#include  
// Click here to get the library: http://librarymanager/All#SparkFun_WM8960
WM8960 codec;

bool buttonState = false;

void setup() {
  AudioMemory(1952);

  // Pins
  pinMode(FOOTSWITCH, INPUT_PULLUP);
  pinMode(LED, OUTPUT);

  Serial.begin(115200);

  Wire.begin();

  if (codec.begin() == false) {
    Serial.println("The audio codec did not respond. Please check wiring.");
    while (1);
  }

  // General setup needed
  codec.enableVREF();
  codec.enableVMID();

  // Set input boosts to get INPUT2 (both left and right) to the boost mixers
  codec.setLIN3BOOST(WM8960_BOOST_MIXER_GAIN_0DB);
  codec.setRIN3BOOST(WM8960_BOOST_MIXER_GAIN_0DB);

  // Enable input boost mixers
  codec.enableAINL();
  codec.enableAINR();

  // Connect from DAC outputs to output mixer
  codec.enableLD2LO();
  codec.enableRD2RO();

  // Set gainstage between booster mixer and output mixer
  // For this loopback example, we are going to keep these as low as they go
  codec.setLB2LOVOL(WM8960_OUTPUT_MIXER_GAIN_0DB); 
  codec.setRB2ROVOL(WM8960_OUTPUT_MIXER_GAIN_0DB);

  // Enable output mixers
  codec.enableLOMIX();
  codec.enableROMIX();

  codec.setWL(WM8960_WL_16BIT);

  // Enable DACs
  codec.enableDacLeft();
  codec.enableDacRight();

  // Enable DACs
  codec.enableAdcLeft();
  codec.enableAdcRight();

  //codec.enableLoopBack(); // Loopback sends ADC data directly into DAC
  codec.disableLoopBack();

  // Default is "soft mute" on, so we must disable mute to make channels active
  codec.disableDacMute();


  codec.enableHeadphones();
  codec.setHeadphoneVolumeDB(6.00);
}

bool enabled = false;
void loop() {
  if (enabled) {
    float levelDry = 1.0f - analogRead(POT1) / 1023.0f;
    float levelWet = 1.0f - analogRead(POT2) / 1023.0f;
    int bits = (1056 - analogRead(POT3)) / 64;

    bitcrusher1.bits(bits);
    bitcrusher2.bits(bits);
    mixer_left.gain(0, levelDry);
    mixer_left.gain(1, levelWet);
    mixer_right.gain(0, levelDry);
    mixer_right.gain(1, levelWet);
  }

  if (digitalRead(FOOTSWITCH)) {
    enabled = !enabled;
    if (!enabled) {
      mixer_left.gain(0, 1);
      mixer_left.gain(1, 0);
      mixer_right.gain(0, 1);
      mixer_right.gain(1, 0);
    }
    digitalWrite(LED, enabled);
    delay(3);
    while (digitalRead(FOOTSWITCH));

  }

  delay(10);
}

Delay Pedal:

#include 
#include 
#include 
#include 
#include

// GUItool: begin automatically generated code
AudioInputI2S2           i2s2_input;         //xy=674,286
AudioEffectDelay         delay_left;         //xy=909,428
AudioEffectDelay         delay_right; //xy=909,561
AudioMixer4              mixer_left;         //xy=1079,401
AudioMixer4              mixer_right; //xy=1084,535
AudioOutputI2S2          i2s2_output;         //xy=1270,466
AudioConnection          patchCord1(i2s2_input, 0, delay_left, 0);
AudioConnection          patchCord2(i2s2_input, 0, mixer_left, 0);
AudioConnection          patchCord3(i2s2_input, 1, delay_right, 0);
AudioConnection          patchCord4(i2s2_input, 1, mixer_right, 0);
AudioConnection          patchCord5(delay_left, 0, mixer_left, 1);
AudioConnection          patchCord6(delay_right, 0, mixer_right, 1);
AudioConnection          patchCord7(mixer_left, 0, i2s2_output, 0);
AudioConnection          patchCord8(mixer_right, 0, i2s2_output, 1);
// GUItool: end automatically generated code



#define POT1 14
#define POT2 15
#define POT3 16
#define FOOTSWITCH 40
#define LED 29


#include  
// Click here to get the library: http://librarymanager/All#SparkFun_WM8960
WM8960 codec;

bool buttonState = false;

void setup() {
  AudioMemory(1952);

  // Pins
  pinMode(FOOTSWITCH, INPUT_PULLUP);
  pinMode(LED, OUTPUT);

  Serial.begin(115200);

  Wire.begin();

  if (codec.begin() == false) {
    Serial.println("The audio codec did not respond. Please check wiring.");
    while (1);
  }

  // General setup needed
  codec.enableVREF();
  codec.enableVMID();

  // Set input boosts to get INPUT2 (both left and right) to the boost mixers
  codec.setLIN3BOOST(WM8960_BOOST_MIXER_GAIN_0DB);
  codec.setRIN3BOOST(WM8960_BOOST_MIXER_GAIN_0DB);

  // Enable input boost mixers
  codec.enableAINL();
  codec.enableAINR();

  // Connect from DAC outputs to output mixer
  codec.enableLD2LO();
  codec.enableRD2RO();

  // Set gainstage between booster mixer and output mixer
  // For this loopback example, we are going to keep these as low as they go
  codec.setLB2LOVOL(WM8960_OUTPUT_MIXER_GAIN_0DB); 
  codec.setRB2ROVOL(WM8960_OUTPUT_MIXER_GAIN_0DB);

  // Enable output mixers
  codec.enableLOMIX();
  codec.enableROMIX();

  codec.setWL(WM8960_WL_16BIT);

  // Enable DACs
  codec.enableDacLeft();
  codec.enableDacRight();

  // Enable DACs
  codec.enableAdcLeft();
  codec.enableAdcRight();

  //codec.enableLoopBack(); // Loopback sends ADC data directly into DAC
  codec.disableLoopBack();

  // Default is "soft mute" on, so we must disable mute to make channels active
  codec.disableDacMute();


  codec.enableHeadphones();
  codec.setHeadphoneVolumeDB(6.00);
}

bool enabled = false;
float levelDry;
float levelWet;
float delaySeconds;
void loop() {
  if (enabled) {
    levelDry = 1.0f - analogRead(POT1) / 1023.0f;
    levelWet = 1.0f - analogRead(POT2) / 1023.0f;
    float newDelaySeconds = (1.0f - analogRead(POT3) / 1023.0f);
    //Serial.printf("Levels: %i %i  Delay: %f\n", (int)(100 * levelDry), (int)(100 * levelWet), (double)delaySeconds);

    if (abs(newDelaySeconds - delaySeconds) / delaySeconds > 0.02f) {
      delaySeconds = newDelaySeconds;
      delay_left.delay(0, delaySeconds * 1000);
      delay_right.delay(0, delaySeconds * 1000);
    }
    mixer_left.gain(0, levelDry);
    mixer_left.gain(1, levelWet);
    mixer_right.gain(0, levelDry);
    mixer_right.gain(1, levelWet);
    delay(50);
  }

  if (digitalRead(FOOTSWITCH)) {
    enabled = !enabled;
    if (!enabled) {
      mixer_left.gain(0, 1);
      mixer_left.gain(1, 0);
      mixer_right.gain(0, 1);
      mixer_right.gain(1, 0);
    }
    digitalWrite(LED, enabled);
    delay(3);
    while (digitalRead(FOOTSWITCH));

  }

  delay(10);
}