Making progress with my DSLR mic monitor Basic filter question

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KrisKasprzak

KrisKasprzak

Well-known member
All,

I'm making good progress with my mic monitor for my DLSR--this device will fit between my lapel mic and my Canon 7D, so i can have dynamic level control. So far i've got working
1. LCD with touch
2. Audio shield
3. FFT
4. slider like gain contol
5. options screen
6. low and high pass filters (but no clue how to set the parameters)

I'm getting some noise though (hiss and a very faint sound like a sci-fi phaser gun). i'm not sure if it's a bad implementation of the audio objects of if I need to add some filtering which I'm trying but not really working, also i'm powering my unit from my PC USB.

Regarding filters, how do you set them
1. if I want to remove everything below say 60 HZ, i use a high pass with frequency at 60 correct?
2. if I want to remove everything above say 10000 hz I use a low pass with the frequency at 10000 correct?
3. how do you disable the filters in code, currently i'm just setting the filters so the won't filter anything--probably not the right way?

I'm not sure what stage and Q really do, right now i'm just swapping values until my noise gets removed--which it's not
thing.setLowpass(stage, frequency, Q);


Anyone wanna look at my code and see if there are any glaring issues that will cause noise? I can strip my code down to the bar min if needed.

Code: 
/*

  This program is a microphone montitor for a DSLR, it will sit between a mic and DSLR input so the user can control the mic levels and see the
  levels.

  Author     Kasprak
  Date       4/8/2018
  revisions
  rev    description             author
  1.0    initial creation        Kasprzak


  connection map


  Teensy 3.2     Display

  0              Touch pin
  1              Touch pin
  2              Touch pin
  3              Touch pin
  4              Touch pin
  5              LED pin (PWM to control brightness)
  6
  7              MOSI
  8
  9
  10
  11
  12             MISO
  13
  14             SCK
  A1
  A2
  A3
  A4
  A5
  A6             Chip Select
  A7             DC
  A8
  A9



*/

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>
#include <ILI9341_t3.h>
#include <Colors.h>         // kasprzaks list of defines for colors, nothing fancy 
#include "UTouch.h"         // touchscreen lib
#include <font_ArialBold.h> // custom fonts that ships with ILI9341_t3.h
#include <font_Arial.h>     // custom fonts that ships with ILI9341_t3.h
#include <EEPROM.h>

#define FILTER_Q   .707
#define MIXGAIN 20
#define MIC_BAR_GAIN  70  // multiplier for the specific mic
#define LED_PIN      5
#define DC_PIN      21
#define CS_PIN      20
#define PIN_RST    255  // 255 = unused, connect to 3.3V
#define MO_PIN     7
#define Display_SCLK    14
#define MI_PIN    12
#define WIDTH 13
#define OFFSET 35
#define HIGHPASS 80
#define LOWPASS 4000

// variables for the locations of the keypad buttons
#define BUTTON_X 100
#define BUTTON_Y 80
#define BUTTON_W 60
#define BUTTON_H 30
#define BUTTON_SPACING_X 10
#define BUTTON_SPACING_Y 10
#define BUTTON_TEXTSIZE 2


ILI9341_t3 Display = ILI9341_t3(CS_PIN, DC_PIN, 240, 320, PIN_RST, MO_PIN, Display_SCLK, MI_PIN);

AudioInputI2S            i2s1;           //xy=100,155
AudioMixer4              mixer1;         //xy=316,91
AudioMixer4              mixer2;         //xy=316,245
AudioFilterBiquad        biquad1;        //xy=499,91
AudioFilterBiquad        biquad2;        //xy=507,246
AudioOutputI2S           i2s2;           //xy=684,181
AudioAnalyzeFFT1024      fft1024_1;      //xy=770,420
AudioConnection          patchCord1(i2s1, 0, mixer1, 0);
AudioConnection          patchCord2(i2s1, 1, mixer2, 0);
AudioConnection          patchCord3(mixer1, biquad1);
AudioConnection          patchCord4(mixer2, biquad2);
AudioConnection          patchCord5(biquad1, 0, i2s2, 0);
AudioConnection          patchCord6(biquad2, 0, i2s2, 1);
AudioConnection          patchCord7(biquad2, fft1024_1);
AudioControlSGTL5000     sgtl5000_1;     //xy=746,53
// GUItool: end automatically generated code


int left,   top  ,  wide ,   high;

int TempNum;
int HighPassF = 0;
int LowPassF = 0;
int MicGain = 5;

byte ShowHistory = 0;
byte Background = 0;
byte Brightness = 255;
byte HighPass = 0;
byte LowPass = 0;
uint16_t BackColor = C_BLACK;
uint16_t ForeColor = C_WHITE;
unsigned long Showit;

char SetupBtnText[8] = "Setup";
char ChangeBtnText[8] = "Set";
char DoneBtnText[8] = "Done";

char FilterText[2][5] = {"Off", "On" };
char HistoryText[2][5] = {"No", "Yes" };
char KeyPadBtnText[12][5] = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "Done", "0", "Clr" };
uint16_t KeyPadBtnColor[12] = {C_BLUE, C_BLUE, C_BLUE,
                               C_BLUE, C_BLUE, C_BLUE,
                               C_BLUE, C_BLUE, C_BLUE,
                               C_DKGREEN, C_BLUE, C_DKRED
                              };
byte Qty, j, i, row, col, b;
int x, y, MixGain, oMixGain;
// An array to hold the 16 frequency bands
float level[16];
float Max[16];
UTouch  Touch( 0, 1, 2, 3, 4);
Adafruit_GFX_Button KeyPadBtn[12];
Adafruit_GFX_Button SetupBtn;
Adafruit_GFX_Button HistoryBtn;
Adafruit_GFX_Button MicGainBtn;
Adafruit_GFX_Button BackColorBtn;
Adafruit_GFX_Button HighPassFBtn;
Adafruit_GFX_Button LowPassFBtn;
Adafruit_GFX_Button DoneBtn;
Adafruit_GFX_Button HighPassBtn;
Adafruit_GFX_Button LowPassBtn;

void setup() {

  pinMode(0, INPUT);
  pinMode(1, INPUT);
  pinMode(2, INPUT);
  pinMode(3, INPUT);
  pinMode(4, INPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);

  Display.begin();
  Display.fillScreen(C_BLACK);
  Display.setRotation(3);

  GetParameters();

  if (Background == 0) {
    BackColor = C_BLACK;
    ForeColor = C_WHITE;
  }

  else {
    BackColor = C_WHITE;
    ForeColor = C_BLACK;
  }

  analogWrite(LED_PIN, Brightness);
  Display.fillScreen(BackColor);

  AudioMemory(12);

  sgtl5000_1.enable();
  sgtl5000_1.volume(.7);
  sgtl5000_1.inputSelect(AUDIO_INPUT_LINEIN);
  sgtl5000_1.lineInLevel(MicGain);
  sgtl5000_1.adcHighPassFilterDisable();

  fft1024_1.windowFunction(AudioWindowHanning1024);

  if (HighPass == 1) {
    biquad1.setHighpass(0, HighPassF, FILTER_Q);
    biquad2.setHighpass(0, HighPassF, FILTER_Q);
  }
  else if (HighPass == 0) {
    biquad1.setHighpass(0, 20,  FILTER_Q);
    biquad2.setHighpass(0, 20, FILTER_Q);
  }

  if (LowPass == 1) {
    biquad1.setLowpass(0, LowPassF,  FILTER_Q);
    biquad2.setLowpass(0, LowPassF,  FILTER_Q);
  }
  else if (LowPass == 0) {
    biquad1.setLowpass(0, 20000,  FILTER_Q);
    biquad2.setLowpass(0, 20000, FILTER_Q);
  }

  Touch.InitTouch();
  Touch.setPrecision(PREC_EXTREME);

  SetupBtn.initButton(&Display,     270, 18, 80, 29, C_DKRED, C_RED, C_WHITE, SetupBtnText, 2);

  HistoryBtn.initButton(&Display,   225, 70, 50, 25, C_DKGREY, C_GREY, C_BLACK, ChangeBtnText, 2);
  MicGainBtn.initButton(&Display,   225, 100, 50, 25, C_DKGREY, C_GREY, C_BLACK, ChangeBtnText, 2);
  HighPassBtn.initButton(&Display,  225, 130, 50, 25, C_DKGREY, C_GREY, C_BLACK, ChangeBtnText, 2);
  LowPassBtn.initButton(&Display,   225, 160, 50, 25, C_DKGREY, C_GREY, C_BLACK, ChangeBtnText, 2);
  HighPassFBtn.initButton(&Display, 280, 130, 50, 25, C_DKGREY, C_GREY, C_BLACK, ChangeBtnText, 2);
  LowPassFBtn.initButton(&Display,  280, 160, 50, 25, C_DKGREY, C_GREY, C_BLACK, ChangeBtnText, 2);
  BackColorBtn.initButton(&Display, 225, 190, 50, 25, C_DKGREY, C_GREY, C_BLACK, ChangeBtnText, 2);

  DoneBtn.initButton(&Display,      270, 18, 80, 29, C_DKRED, C_RED, C_WHITE, DoneBtnText, 2);

  // create KeyPadBtn
  for (row = 0; row < 4; row++) {
    for (col = 0; col < 3; col++) {
      KeyPadBtn[col + row * 3].initButton(&Display, BUTTON_X + col * (BUTTON_W + BUTTON_SPACING_X),
                                          BUTTON_Y + row * (BUTTON_H + BUTTON_SPACING_Y),
                                          BUTTON_W, BUTTON_H, C_WHITE, KeyPadBtnColor[col + row * 3], C_WHITE,
                                          KeyPadBtnText[col + row * 3], BUTTON_TEXTSIZE);
    }
  }

  delay(100);

  y = 150;
  MixGain = y;
  oMixGain = y;

  mixer1.gain(0, (220 - MixGain) / MIXGAIN);
  mixer2.gain(0, (220 - MixGain) / MIXGAIN);

  DrawMainScreen();
  DrawGain();

}

void loop() {

  if (fft1024_1.available()) {

    ProcessTouch();

    level[0] =  fft1024_1.read(0) * 1.21 * MIC_BAR_GAIN;
    level[1] =  fft1024_1.read(1) * 1.18 * MIC_BAR_GAIN;
    level[2] =  fft1024_1.read(2, 3) * 1.15 * MIC_BAR_GAIN;
    level[3] =  fft1024_1.read(4, 6) * 1.12 * MIC_BAR_GAIN;
    level[4] =  fft1024_1.read(7, 10) * 1.09 * MIC_BAR_GAIN;
    level[5] =  fft1024_1.read(11, 15) * 1.06 * MIC_BAR_GAIN;
    level[6] =  fft1024_1.read(16, 22) * 1.03 * MIC_BAR_GAIN;
    level[7] =  fft1024_1.read(23, 32) * 1.00 * MIC_BAR_GAIN;
    level[8] =  fft1024_1.read(33, 46) * 0.96 * MIC_BAR_GAIN;
    level[9] =  fft1024_1.read(47, 66) * 0.93 * MIC_BAR_GAIN;
    level[10] = fft1024_1.read(67, 93) * 0.90 * MIC_BAR_GAIN;
    level[11] = fft1024_1.read(94, 131) * 0.87 * MIC_BAR_GAIN;
    level[12] = fft1024_1.read(132, 184) * 0.84 * MIC_BAR_GAIN;
    level[13] = fft1024_1.read(185, 257) * 0.81 * MIC_BAR_GAIN;
    level[14] = fft1024_1.read(258, 359) * 0.78 * MIC_BAR_GAIN;
    level[15] = fft1024_1.read(360, 511) * 0.75 * MIC_BAR_GAIN;

    for (i = 0; i < 16; i++) {  // cycle through the 16 channels

      int line1 = level[i] * 180;

      if (line1 > 180) {
        line1 = 180;
      }

      // get number of bars
      Qty = line1 / 10;
      for (j = Qty; j < 18; j++) {
        Display.fillRect(  (i * WIDTH) + OFFSET, 220 - (j * 10), WIDTH - 1, 9, BackColor);
      }
      if (ShowHistory) {
        if (Qty > Max[i]) {
          Max[i] = Qty - 1;
        }
        if ((millis() - Showit ) > 2000) {
          Showit = millis();
          for (byte k = 0; k < 16; k++) {
            Display.fillRect((i * WIDTH) + OFFSET, 220 - (Max[k] * 10), WIDTH - 1, 9, BackColor);
            Max[k] = 0;
          }
        }
        else {
          if (Max[i] < 12) {
            Display.fillRect( (i * WIDTH) + OFFSET, 220 - (Max[i] * 10), WIDTH - 1, 9, C_GREEN);
          }
          else if (Max[i] < 16) {
            Display.fillRect( (i * WIDTH) + OFFSET, 220 - (Max[i] * 10), WIDTH - 1, 9, C_YELLOW);
          }
          else {
            Display.fillRect( (i * WIDTH) + OFFSET, 220 - (Max[i] * 10), WIDTH - 1, 9, C_RED);
          }
        }
      }
      for ( j = 0; j < Qty; j++) {
        if (j < 12) {
          Display.fillRect(  (i * WIDTH) + OFFSET, 220 - (j * 10), WIDTH - 1, 9, C_GREEN);
        }
        else if (j < 16) {
          Display.fillRect(  (i * WIDTH) + OFFSET, 220 - (j * 10), WIDTH - 1, 9, C_YELLOW);
        }
        else {
          Display.fillRect(  (i * WIDTH) + OFFSET, 220 - (j * 10), WIDTH - 1, 9, C_RED);
        }
      }

      Display.setFont(Arial_12_Bold);
      Display.setTextColor(ForeColor, BackColor);

      Display.setCursor(2, 220);
      Display.print(F("-o")) ;
      Display.setCursor(16, 220);
      Display.print(F("o")) ;

      Display.setCursor(2, 100);
      Display.print(F("-12")) ;;

      Display.setCursor(2, 45);
      Display.print(F("+3")) ;;

      Display.drawFastHLine( 27, 229, 215, C_GREY);
      Display.drawFastHLine( 27, 109, 215, C_GREY);
      Display.drawFastHLine( 27, 49, 215, C_GREY);

    }
  }
}

void DrawMainScreen() {

  Display.setFont(Arial_18_Bold);

  Display.setTextColor(C_DKGREY, BackColor);
  Display.setCursor(5, 7);
  Display.print("DSLR Mic Monitor");

  Display.setTextColor(C_BLUE, BackColor);
  Display.setCursor(3, 5);
  Display.print("DSLR Mic Monitor");

  Display.setFont(Arial_14);
  SetupBtn.drawButton();

}

void DrawGain() {

  // clear old button
  Display.fillRoundRect (266, oMixGain, 45, 20, 3, BackColor);

  Display.fillRoundRect( 258, 40, 60,   190, 6, C_GREY);
  Display.drawRoundRect( 258, 40, 60,   190, 6, C_DKGREY);

  Display.fillRect( 275, 60, 3,   140, C_BLACK);
  Display.fillRect( 298, 60, 3,   140, C_BLACK);

  Display.fillRoundRect (266, MixGain, 45, 18, 3, C_DKGREY);
  Display.drawRoundRect (266, MixGain, 45, 18, 3, C_GREY);

  Display.setFont(Arial_12_Bold);
  Display.setTextColor(C_BLACK, BackColor);
  Display.setCursor(270, 45);
  Display.print(F("Gain")) ;

  Display.setCursor(275, 205);
  Display.print(F("L")) ;
  Display.setCursor(295, 205);
  Display.print(F("R")) ;

  mixer1.gain(0, (220 - MixGain) / MIXGAIN);
  mixer2.gain(0, (220 - MixGain) / MIXGAIN);

}

void ProcessTouch() {

  if (Touch.dataAvailable()) {

    Touch.read();

    x = Touch.getX();
    y = Touch.getY();
    delay(50); // debounce the touch

    if (PressIt(SetupBtn, x, y) == true) {
      SetupScreen();
      return;
    }

    else if ((x > 250) & (y > 53) & (y < 190)) {
      //oMixGain = MixGain;
      MixGain = y;
      if (oMixGain != MixGain) {
        oMixGain = MixGain;
        DrawGain();
      }

    }

    else if (( x > 10) & (x < 200)) {

      Brightness = map(y, 0, 240, 255, 10);

      analogWrite(LED_PIN, Brightness);
    }

  }

}

void SetupScreen() {

  bool KeepIn = true;

  DrawSetupScreen();

  while (KeepIn) {

    if (Touch.dataAvailable()) {

      Touch.read();

      x = Touch.getX();
      y = Touch.getY();

      if (PressIt(HistoryBtn, x, y) == true) {
        if (ShowHistory == 1) {
          ShowHistory = 0;
        }
        else if (ShowHistory == 0) {
          ShowHistory = 1;
        }
        DrawSetupScreen();
      }

      if (PressIt(MicGainBtn, x, y) == true) {
        KeyPad(MicGain, 5, 15);
        sgtl5000_1.lineInLevel(MicGain);
      }

      if (PressIt(BackColorBtn, x, y) == true) {
        if (Background == 0) {
          Background = 1;
          BackColor = C_WHITE;
          ForeColor = C_BLACK;
          DrawSetupScreen();
        }

        else {
          Background = 0;
          BackColor = C_BLACK;
          ForeColor = C_WHITE;
          DrawSetupScreen();
        }
        // save back color
      }

      if (PressIt(HighPassBtn, x, y) == true) {
        if (HighPass == 0) {
          HighPass = 1;
          biquad1.setHighpass(0, HighPassF,  FILTER_Q);
          biquad2.setHighpass(0, HighPassF,  FILTER_Q);
        }
        else if (HighPass == 1) {
          HighPass = 0;
          biquad1.setHighpass(0, 20, FILTER_Q);
          biquad2.setHighpass(0, 20, FILTER_Q);
        }
        DrawSetupScreen();
      }

      if (PressIt(LowPassBtn, x, y) == true) {
        if (LowPass == 0) {
          LowPass = 1;
          biquad1.setLowpass(0, LowPassF, FILTER_Q);
          biquad2.setLowpass(0, LowPassF, FILTER_Q);
        }
        else if (LowPass == 1) {
          LowPass = 0;
          biquad1.setLowpass(0, 20000, FILTER_Q);
          biquad2.setLowpass(0, 20000, FILTER_Q);
        }
        DrawSetupScreen();
      }

      if (PressIt(HighPassFBtn, x, y) == true) {
        KeyPad(HighPassF, 20, 400);
        DrawSetupScreen();
      }

      if (PressIt(LowPassFBtn, x, y) == true) {
        KeyPad(LowPassF, 400, 20000);
        DrawSetupScreen();
      }

      if (PressIt(DoneBtn, x, y) == true) {
        KeepIn = false;
      }
    }
  }

  // save data and exit
  EEPROM.put(10, ShowHistory);
  EEPROM.put(20, Background);
  EEPROM.put(30, MicGain);
  EEPROM.put(40, HighPass);
  EEPROM.put(50, LowPass);
  EEPROM.put(60, HighPassF);
  EEPROM.put(70, LowPassF);
  Display.fillScreen(BackColor);
  DrawMainScreen();
  DrawGain();
}


void DrawSetupScreen() {

  Display.fillScreen(BackColor);

  Display.setFont(Arial_18_Bold);

  Display.setTextColor(C_DKGREY, BackColor);
  Display.setCursor(5, 7);
  Display.print("Setup");
  Display.setTextColor(C_BLUE, BackColor);
  Display.setCursor(3, 5);
  Display.print("Setup");

  Display.setFont(Arial_12_Bold);

  Display.setTextColor(ForeColor, BackColor);

  HistoryBtn.drawButton();
  MicGainBtn.drawButton();
  HighPassBtn.drawButton();
  LowPassBtn.drawButton();
  HighPassFBtn.drawButton();
  LowPassFBtn.drawButton();
  BackColorBtn.drawButton();
  DoneBtn.drawButton();

  Display.setTextColor(ForeColor, BackColor);
  Display.setFont(Arial_12);
  Display.setCursor(10 , 65);
  Display.print("Show bar history: " + String(HistoryText[ShowHistory]));
  Display.setCursor(10 , 95);
  Display.print("Microphone gain: " + String(MicGain));
  Display.setCursor(10 , 125);
  Display.print("High Pass: " + String(FilterText[HighPass]) + ", " + String(HighPassF) + " hz");
  Display.setCursor(10 , 155);
  Display.print("Low Pass: " + String(FilterText[LowPass]) + ", " + String(LowPassF) + " hz");
  Display.setCursor(10 , 185);
  Display.print("Background color");

}


/*

  Function to draw a keypad input screen
  Potential edits: possibly button colors

*/

void KeyPad(int & TheNumber, int MinVal, int MaxVal) {

  Display.setFont(Arial_14);

  left = BUTTON_X - (BUTTON_W);
  top = BUTTON_Y - (2 * BUTTON_H);
  wide = (3 * BUTTON_W ) + (8 * BUTTON_SPACING_X);
  high = 5 * (BUTTON_H +  BUTTON_SPACING_Y);
  TempNum = TheNumber;
  bool KeepIn = true;

  Display.fillRect(left, top, wide , high, C_DKGREY);
  Display.drawRect(left, top, wide , high, C_LTGREY);

  Display.fillRect(left + 10, top + 10, wide - 20 , 30, C_GREY);
  Display.drawRect(left + 10, top + 10, wide - 20 , 30, C_WHITE);

  Display.setCursor(left  + 110 , top + 18);
  Display.setTextColor(C_BLACK, 80);
  Display.print("(" + String(MinVal) + " - " + String(MaxVal) + ")");

  Display.setCursor(left  + 20 , top + 18);
  Display.setTextColor(C_BLACK, C_GREY);
  Display.print(TheNumber);

  for (row = 0; row < 4; row++) {
    for (col = 0; col < 3; col++) {
      KeyPadBtn[col + row * 3].drawButton();
    }
  }

  while (KeepIn) {
    // get the touch point
    if (Touch.dataAvailable()) {

      Touch.read();

      x = Touch.getX();
      y = Touch.getY();

      // go thru all the KeyPadBtn, checking if they were pressed
      for (b = 0; b < 12; b++) {
        if (PressIt(KeyPadBtn[b], x, y) == true) {
          if ((b < 9) | (b == 10)) {
            TempNum *= 10;
            if (TempNum == 0) {
              Display.fillRect(left + 10, top + 10, 80 , 30, C_GREY);
            }


            if (b != 10) {
              TempNum += (b + 1);
            }
            if (TempNum > MaxVal) {
              Display.fillRect(left + 10, top + 10, 80 , 30, C_GREY);
              TempNum = TempNum / 10;
              //  TempNum -= (b + 1);
            }
          }
          // clr button! delete char
          if (b == 11) {
            Display.fillRect(left + 10, top + 10, 80 , 30, C_GREY);
            Display.drawRect(left + 10, top + 10, 80 , 30, C_WHITE);
            TempNum = 0;
          }
          if (b == 9) {
            if (TempNum >= MinVal) {
              KeepIn = false;
            }
          }
          Display.setCursor(left  + 20 , top + 18);
          Display.setTextColor(C_BLACK, C_GREY);
          Display.print(TempNum);

        }
      }
    }
  }

  TheNumber = TempNum;
  DrawSetupScreen();

}

void GetParameters() {

  byte i, test;

  EEPROM.get(0, test);
  if (test == 255) {
    // new programmer reset the whole thing
    for (i = 0; i < 255; i++) {
      EEPROM.put(i, 0);
    }
    // set some defaulTouch
    // and populate the eeprom

    ShowHistory = 0;
    EEPROM.get(10, ShowHistory);
    Background = 0;
    EEPROM.put(20, Background);
    MicGain = 5;
    EEPROM.put(30, MicGain);
    HighPass = 0;
    EEPROM.put(40, HighPass);
    LowPass = 0;
    EEPROM.put(50, LowPass);
    HighPassF = 4000;
    EEPROM.put(40, HighPassF);
    LowPassF = 40;
    EEPROM.put(50, LowPassF);

  }

  EEPROM.get(10, ShowHistory);
  EEPROM.get(20, Background);
  EEPROM.get(30, MicGain);
  EEPROM.get(40, HighPass);
  EEPROM.get(50, LowPass);
  EEPROM.get(60, HighPassF);
  EEPROM.get(70, LowPassF);
}


/*

  function to proccess a button press
  Potential edits: modify delay to change debounce behavior

*/


bool PressIt(Adafruit_GFX_Button TheButton, int x, int y) {

  if (TheButton.contains(x, y)) {
    TheButton.press(true);  // tell the button it is pressed
  } else {
    TheButton.press(false);  // tell the button it is NOT pressed
  }
  if (TheButton.justReleased()) {
    TheButton.drawButton();  // draw normal
  }
  if (TheButton.justPressed()) {
    TheButton.drawButton(true);  // draw invert!
    delay(200); // UI debouncing
    TheButton.drawButton(false);  // draw invert!
    return true;
  }
  return false;
}
 
If you had a USB Battery pack that might give a quick read on the noise source. USB power from PC is a common noisemaker It seems.

Not sure if Hub - powered or not - versus direct PC connect might add some supply filtering?

Could be the SPI display? Or the touch reading? Unplug that if socketed - but that will leave the data streaming the wires if output not stopped or slowed. Recent experience with SPI between two Teensy units on SPI that was talking each loop was interfering with GPS satellite reception.
 
@defragster I tried using a battery USB charger -- no help, i unplugged my display not help. I've also tried different mics--same issue.

Note i have my audio board soldered UNDER my teensy 3.2--the teensy is on top where the teensy pins slide right through the audio board holes--then soldered into place. I see all other implementation with the audio board on top--could that be an issue?

I'll post the sound output so you can hear what the problem is.

Thanks for responding.
 
All

I've posted a private YouTube vid (hopefully you can watch it). Notice the excessive background noise, and the weird faint alien space gun noise in the left channel. skip to the 2:09 to see what the noise is like with the mic plugged directly into the camera.

Any thoughts?

 
Nice UI on the touch display.

Can see and hear the vid - others may have experience to hear and make suggestions - I hear the alien noise - perhaps CPU processing noise? Wonder what CPU speed is in use - and what happens to that sound if slowed to 72 or 48 MHz? That alien processor cycling went away at higher gain - when you heard hiss go higher.
 
defragster,

since my last post i soldered the 3.5 mm jack directly to the audio board (the connections were using solderless breadboard type wires), and the noise went away almost completely, but some crept back in after several minutes--odd I know. The unit seems to do that though, on first startup, the noise is less, but after running for a few min it seems to sound like what I have in the video. I will make a PCB board to eliminate all wires completely.

I've tried 48 mhz up to 120 mhz on the cpu (120 seems to be the best), but with the improved solder connection, i'll retry different cpu speeds.

Have any example snipped code on the proper usage of a high and low pass filter? Something tells me my implementation is not correct--especially for disabling the filter

Thanks for responding.
 
All,

Before i etch a PCB board for my "DSLR Mic Monitor" do you think i need any ground traces around other vital traces? The audio board will be soldered directly to the T3, and there will be very short jumpers between the 3.5 mm mic jack and the audio board.

Components i'm using
T3
Audio board
Buck converter (powered by a 9V battery)
2.8 inch touch display
3.5 mm audio jack

The board will be a single sided only as i'm a garage DIY kinda guy and can't do double sided.

My main goals are to reduce noise as much as possible.

Think this will work regarding minimizing noise?

PCB.jpg

Thanks in advance.
 
Why don't you use an Lithium-Accu instead a Buck-Converter? The noise will be reduce and the battery-life is longer as a 9V Battery.

You made a mistake on your board-layout! Teensy Pin 3 is a output not an input, change 3,3 V to Pin1 Vin!
 
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Josh911, I tried connected a USB battery charger directly to the Teensy, and no difference in hiss. I did add a DC blocking cap (0.1 uF) to the mic and it eliminated the alien sound, but I still have the hiss.

oddly if i set the gain to 0, i still hear hiss in the audio output.

mixer1.gain(0, 0);
mixer2.gain(0, 0);

Thoughts?
 
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