gistfile1.ino

void loop() {
  ...
    
  if (state == IDLE) {
    //Start? If an interval is given, and there is no error.
    if ((digitalRead(RUN_BTN) == HIGH) && (interval != 0) && !has_error) { setState(RUN); beep(); return; }

    //Are some buttons pressed? Adjust the interval.
    boolean p1 = (digitalRead(P1_BTN) == LOW);
    boolean p10 = (digitalRead(P10_BTN) == LOW);
    if (p1 || p10) {
      if (p1 && p10) { interval = 0; }  //Reset interval
      else if (p1) { interval += 60; }  //+1 minute
      else if (p10) { interval += 600; }//+10 minutes
      
      Serial.print("Updated interval: ");
      displayTime(interval);
      beep();
    }
  }
  
  ...
}

/**
 * Display the given interval on the screen
 * @param time The time, in seconds
 */
void displayTime(int time) {
  time_display.writeDigitNum(0, (time / 600));
  time_display.writeDigitNum(1, (time / 60) % 10);
  time_display.drawColon(true);
  time_display.writeDigitNum(3, (time / 10) % 6);
  time_display.writeDigitNum(4, (time % 10));
  time_display.writeDisplay();

  Serial.write('0' + (time / 600) );
  Serial.write('0' + ((time / 60) % 10) );
  Serial.write(':');
  Serial.write('0' + ((time / 10) % 6) );
  Serial.write('0' + (time % 10) );
  Serial.write('\n');  
}

/**
 * Sound the buzzer for a short or long period
 */
void beep() { digitalWrite(BUZZER, HIGH); delay(500); digitalWrite(BUZZER, LOW); }
void beeeep() { digitalWrite(BUZZER, HIGH); delay(2000); digitalWrite(BUZZER, LOW); }