// Sketch adapted from Dave Melis's Touch sensor code for 
// ATtiny, to run on Adafruit Gemma 

//Things changed:
//-Pin numbers: Although the Gemma is an ATtiny board,
// not all of the ATtiny's pins are 'broken out' aka able to be connected to 
//- Two separate touch sensors: Pin 1 and Pin 2 are both touch
//sensors that can be set to trigger different things

//The Gemma has 3 pin (0,1,2). As two are used for touch sensing
//this leaves just one for lighting leds
int togglepin = 3; // the led that's toggled when you touch the input pin
//Gemma doesn't have a pin 3, so this part of the code isn't being used
int steadypin = 1; // the led that's on while you're touching the input pin
//Pin 1 an i/o pin, but it's also connected to the onboard led on the Gemma
//Which is handy because it means you don't have to connect an external led to see this work

int calibration = 0; //calibrating the first touch sensor
int calibration2 = 0; //calibrating the second touch sensor

int previous; //this variable is used for toggling the led on and off
int togglestate = LOW;

void setup()
{
  //pinMode(togglepin, OUTPUT); //commented out as it's not being used
  pinMode(steadypin, OUTPUT);
  
  delay(100);

  //Calibrate the first touch sensor - pin 2 aka PB2
  for (int i = 0; i < 8; i++) {
    calibration += chargeTime(PB2);
    delay(20);
  }
  calibration = (calibration + 4) / 8;

  //Calibrate the second touch sensor - pin 0 ak PB0
    for (int i = 0; i < 8; i++) {
    calibration2 += chargeTime(PB0);
    delay(20);
  }
  calibration2 = (calibration2 + 4) / 8;
}

void loop()
{
  int n = chargeTime(PB2);
  int n2= chargeTime(PB0);

  //If pin 2 is being touched, turn on the LED at full brightness
  if (n > calibration ) digitalWrite(steadypin, HIGH);
  //If pin 0 is being touched, turn on the LED at low brightness 
  else if (n2 > calibration2 ) analogWrite(steadypin,20);
  //If nothing is being touched, turn off the led
  else digitalWrite(steadypin, LOW);

////This part is for toggling the led, which we're not using at the moment
//  if (previous <= calibration && n > calibration) {
//    if (togglestate == LOW) togglestate = HIGH;
//    else togglestate = LOW;
//    digitalWrite(togglepin, togglestate);
//  }
//  
//  previous = n;
  
  delayMicroseconds(500);
}

//This function detects if a pin is being touched
byte chargeTime(byte pin)
{
  byte mask = (1 << pin);
  byte i;

  DDRB &= ~mask; // input
  PORTB |= mask; // pull-up on

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

  PORTB &= ~mask; // pull-up off
  DDRB |= mask; // discharge

  return i;
}