// https://wokwi.com/projects/385841513818337281
// https://forum.arduino.cc/t/fader-pickup-catch-mode/1206227


#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);


void setup()
{
  Serial.begin(31250);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Output    Input");

}

bool pickupmode = true;
int midiVal;
const int FaderA = A0;
const int FaderB = A1;

int midiInVal = 127;
int temp = 127;
int threshold = 4;

void loop()
{
  
int valA = map(analogRead(FaderA),0,1023,0,127);
int valB = map(analogRead(FaderB),0,1023,0,127);

lcd.setCursor(0, 1);
lcd.print(midiVal);
lcd.print("         ");
lcd.print(midiInVal);
lcd.print("      ");


// In absolute mode (default behaviour)
if (!pickupmode){
  midiVal = valA;
  midiInVal = midiVal; // This line is just for the simulation

  // Toggle to pickup mode (when received midi value is different to current midi out value)
  if (valA != midiInVal) {
      pickupmode = true;  
    }

  if (valB != temp) {
      pickupmode = true;  

  }
}

// In pick up/takeover mode
if (pickupmode){
      midiInVal = valB; // This line is just for the simulation
      temp = midiInVal;
  
  // Toggle to absolute mode when value picked up
  if (abs(valA - midiInVal) <= threshold) {

      pickupmode = false;  
    }
}



  Serial.print("valA = ");
  Serial.print(valA);
  Serial.print("\t");
  Serial.print("valB = ");
  Serial.print(valB);
  Serial.print("\t");
  Serial.print("Midi Out = ");
  Serial.print(midiVal);
  Serial.print("\t");
  Serial.print("Midi In = ");
  Serial.print(midiInVal);
  Serial.print("\t");
  Serial.print("Temp = ");
  Serial.print(temp);
  Serial.print("\t");
  if (pickupmode){Serial.println("Pickup mode");
  }
  else { Serial.println("Absolute mode");
    }

}