/*
  Reference: https://arbaranwal.github.io/tutorial/2017/06/23/atmega328-register-reference.html
             https://playground.arduino.cc/Code/BitMath/
*/

void demo1() {
  for (int i = 0; i <= 7; i++) pinMode(i, OUTPUT);
  //DDR -  Data Direction Register
  //DDR - 1 OUTPUT, 0 INPUT
  //等价于 pinMode();
  //DDRD = 0b11111111;

  for (int i = 0; i <= 7; i++) digitalWrite(i, HIGH);
  //PORT - Defines state of Output Pins
  //PORT - 1 HIGH, 0 LOW
  //等价于 digitalWrite
  //PORTD = 0b10101011;

  Serial.print("0b");
  for (int i = 0; i <= 7; i++) Serial.print(digitalRead(i));
  //PIN -  Reads state of Input Pins
  //等价于 digitalRead
  //Serial.println(PIND,BIN);
}

void demo2() {
  Serial.println("-----------------");
  Serial.println("INPUT_PULLUP DEMO");
  //A0 - 14 A5-19
  for (int i = 14; i <= 18; i++) pinMode(i, INPUT_PULLUP);
  //INPUT_PULLUP 可以用 DDRC 和 PORTC组合实现
  //DDRC = 0b00000000;
  //PORTC = 0b00111111;
  Serial.print("A0-A5 0b");
  Serial.println(PINC, BIN);
}

void demo3() {
  // 使用 二进制 OR 操作 仅将A5 设置为OUTPUT HIGH
  DDRC = DDRC | 0b00100000;
  PORTC = PORTC | 0b00100000;

  // 使用 AND 和 NOT 的组合 仅将A5 设置OUTPUT LOW
  delay(3000);
  PORTC = PORTC & ~(0b00100000);

  // 使用 二进制 AND 操作 仅获得A5 的状态
  if (PINC & 0b00100000) {
    Serial.print("A5 Status is HIGH");
  } else {
    Serial.print("A5 Status is LOW");
  }

}

void demo4() {
  //二进制高阶
  PORTD &= ~(1 << 3); //D3 = LOW
  PORTD &= ~(7 << 3); //D3,D4和D5 = LOW
  PORTD |= (1 << 4); //D4 = HIGH
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  //demo1(); //basic
  demo2(); //INPUT_PULLUP
  //demo3(); //二进制运算基础
  //demo4(); //二进制运算高阶


}

void loop() {
  // put your main code here, to run repeatedly:
  // 使用 NOT 进行反转
  //PORTD = ~PORTD;
  //delay(500);
}