#include <LiquidCrystal_I2C.h>
int lcdColumns = 21;
int lcdRows = 22;
const int trigPin =15;
const int echoPin = 2;
long duration;
float distanceCm;
float distanceInch;

#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701
LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows);  
void setup(){
  lcd.init();                     
  lcd.backlight();
  Serial.begin(115200); 
  pinMode(trigPin, OUTPUT); 
  pinMode(echoPin, INPUT); 
  Serial.begin(9600);
}

void loop(){
        char plaintext[] = "lizhuo";  // 明文
    int key = 7;  // 密钥为7
    int length = strlen(plaintext);  // 使用strlen获取明文长度

    // 使用凯撒密码加密并输出密文
    for (int i = 0; i < length; i++) {
        if (plaintext[i] >= 'A' && plaintext[i] <= 'Z') {
            Serial.print((char)(((plaintext[i] - 'A' + key) % 26) + 'A'));
        } else if (plaintext[i] >= 'a' && plaintext[i] <= 'z') {
            Serial.print((char)(((plaintext[i] - 'a' + key) % 26) + 'a'));
        } else {
            Serial.print(plaintext[i]);  // 非字母字符不变
        }
    }
    Serial.println(); // 输出换行符
    while (true) {}  //为保持串口输出的整洁，所以让程序一直循环while
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distanceCm = duration * SOUND_SPEED/2;
  
  distanceInch = distanceCm * CM_TO_INCH;
  
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
  Serial.print("Distance (inch): ");
  Serial.println(distanceInch);
  lcd.setCursor(0, 0);
  lcd.print("Distance");
  lcd.setCursor(0,1);
  lcd.print(distanceCm);
  lcd.print(" cm");
  delay(1000);
  lcd.clear();
}