Arduino code. See: http://fab.cba.mit.edu/classes/863.15/section.CBA/people/Schaad/week8-embedded-programming.html

att44_arduino_schaad1.ino

//
//  att44_arduino_schaad1.ino
//
//  Created by Raphael Schaad on 2015-11-03.
//  This is free and unencumbered software released into the public domain.
//

// Hardware:
// Based on Neil Gershenfeld's board: http://academy.cba.mit.edu/classes/embedded_programming/index.html#echo
// With my redesign and enhancements: http://fab.cba.mit.edu/classes/863.15/section.CBA/people/Schaad/week6-electronics-design.html
const int LED1 = 8; // (red)   on Pin 8 (PWM)                 physical pin 5
const int LED2 = 2; // (green) on Pin 2 (Analog Input 2)      physical pin 11
const int LED3 = 3; // (green) on Pin 3 (Analog Input 3)      physical pin 10
const int BTN1 = 7; //         on Pin 7 (PWM, Analog Input 7) physical pin 6

// capacitive touch: touch an input pin + GND http://highlowtech.org/?p=1653
//int calibration = 0;
//int previous = 0;

int buttonState = LOW;

void setup() {
// capacitive touch
//  for (int i = 0; i < 8; i++) {
//    calibration += chargeTime(BTN1);
//    delay(20);
//  }
//  calibration = (calibration + 4) / 8;

  // Configure digital I/O pins
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  // If this was just INPUT, digitalRead(BTN1) would *always* be LOW.
  // With INPUT_PULLUP, digitalRead(BTN1) will be HIGH by default, and LOW when the button is pressed.
  // https://www.arduino.cc/en/Reference/Constants
  // https://www.arduino.cc/en/Tutorial/DigitalPins
  pinMode(BTN1, INPUT_PULLUP);
}

void loop() {
// capacitive touch
//  int n = chargeTime(BTN1);
//  // (n > calibration) indicates touch
//  if (previous <= calibration && n > calibration) {
//    // toggle
//    if (buttonState == LOW) {
//      buttonState = HIGH;
//    } else {
//      buttonState = LOW;
//    }
//  }
//  previous = n;
//  delay(100);

  buttonState = digitalRead(BTN1);
  if (buttonState == HIGH) {
      // Clear
      digitalWrite(LED2, LOW);
      digitalWrite(LED3, LOW);

      // Fading: https://www.arduino.cc/en/Tutorial/PWM (only pint at LED1 supports this)
      // The real max is 255 but the difference in the higher values is visually not as discernible
      const int brightnessMax = 100;
      for (int i = 0; i <= brightnessMax; i++) {
        analogWrite(LED1, i);
        delay(10);
      }
      for (int i = brightnessMax - 1; i >= 0; i--) {
        analogWrite(LED1, i);
        delay(10);
      }
  } else {
    // Blinking
    digitalWrite(LED2, HIGH);
    digitalWrite(LED3, LOW);
    delay(200); // in ms
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, HIGH);
    delay(200);
  }
}

// capacitive touch
byte chargeTime(byte pin) {
  byte mask = (1 << pin);
  byte i;

  DDRA &= ~mask; // input
  PORTA |= mask; // pull-up on

  for (i = 0; i < 16; i++) {
    if (PINA & mask) break;
  }

  PORTA &= ~mask; // pull-up off
  DDRA |= mask; // discharge

  return i;
}