#include <Keyboard.h> // pull up library

#define N_TOUCH 6 // define touch pads
#define THRESHOLD 30 // define sensitivity level
int touch_pins[N_TOUCH] = {3, 4, 2, 27, 1, 26}; // numbers that correspond to pads
int touch_values[N_TOUCH] = {0, 0, 0, 0, 0, 0}; // value for each touchpad, higher value means more capacitance
bool pin_touched_now[N_TOUCH] = {false, false, false, false, false, false};
bool pin_touched_past[N_TOUCH] = {false, false, false, false, false, false};

void update_touch() { // void means return no output
  int t; // t is how long it takes to touch the pad to charge
  int t_max = 200; // this ensure the code doesnt get stuck in an infinite loop
  int p; // temporary variable to hold the pin number being tested
  for (int i = 0; i < N_TOUCH; i++) { // this is a for loop that starts at i; essentially this code checks the pin number for each pad
    p = touch_pins[i];
    pinMode(p, OUTPUT); // this sets the pin to OUTPUT ( in order to drive signals) and set the pin to LOW so that it starts with 0 volts
    digitalWriteFast(p, LOW);
    delayMicroseconds(25); // this delay allows the pin to fully discharge
    noInterrupts(); // pauses other events 
    pinMode(p, INPUT_PULLUP); // change pin to input with pull-up resistor
    t = 0;
    while (!digitalReadFast(p) && t < t_max) { // while loop that checks if the pin has reached HIGH
      t++;
    }
    touch_values[i] = t;
    interrupts();
    pin_touched_past[i] = pin_touched_now[i];
    pin_touched_now[i] = touch_values[i] > THRESHOLD;
  }
}

void setup() {
  Serial.begin(115200);
  Keyboard.begin();  // start HID keyboard mode
}

void loop() {
  update_touch();

  // Example: Touch pad 0 types "A" when pressed
  if (pin_touched_now[0] && !pin_touched_past[0]) {
    Keyboard.write('Tyler Barron');
  }

  // Example: Touch pad 1 types Enter when pressed
  if (pin_touched_now[1] && !pin_touched_past[1]) {
    Keyboard.write(KEY_RETURN);
  }

  // Optional: debug print values
  for (int i=0; i<N_TOUCH; i++) {
    Serial.print(touch_values[i]);
    Serial.print(" ");
  }
  Serial.println();

  delay(50);
}