const int stepsPerRevolution = 200;
int datapin = 2; 
int clockpin = 3;
int latchpin = 4;
byte data = 0;
#define ECHO_PIN 5
#define TRIG_PIN 6
#include <LiquidCrystal_I2C.h>
#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);
#include "U8glib.h"
U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_DEV_0 | U8G_I2C_OPT_NO_ACK | U8G_I2C_OPT_FAST);
const int LED_GREEN=11;
const int LED_YELLOW=12;

void setup() {
  pinMode(datapin, OUTPUT);
  pinMode(clockpin, OUTPUT);  
  pinMode(latchpin, OUTPUT);
  u8g.setFont(u8g_font_tpssb);
  u8g.setColorIndex(1);
  lcd.init();
  lcd.backlight();
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT); //设置led 灯的接口模式
  pinMode(ECHO_PIN, INPUT);
  pinMode(TRIG_PIN, OUTPUT);//传感器接口模式应该怎么办？ 
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_YELLOW, OUTPUT);
}

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);  //触发接口写入低电平
  delayMicroseconds(2);       //睡个2毫秒
  digitalWrite(TRIG_PIN, HIGH); //触发接口写入高电平
  delayMicroseconds(2); //持续发送个2毫秒
  digitalWrite(TRIG_PIN, LOW); //一个脉冲过去了，停止发送-写入低电平。
  int duration = pulseIn(ECHO_PIN, HIGH); //声明了一个变量，是脉冲的时间长度，它的计算是靠pulseIn函数，接口是
     //接收接口-echo_pin, 计算的是脉冲高电平的时间。 
  return duration * 0.034 / 2; //返回一个基于duration变量所计算出的最终数值，计算公式= 时间长度* 超声波速度
}

void loop() {
  float distance=readDistanceCM();//声明了一个变量距离，用调用readDistanceCM（）计算器函数给的返回值来赋值

  /*if(distance < 50){
    digitalWrite(13, HIGH);
  }
  else if (distance<100 && distance>50){
     digitalWrite(11, HIGH);
  }
  else{
    digitalWrite(12,HIGH);
  }*/

  digitalWrite(LED_BUILTIN, distance < 50);//写入isNearby 对应的电平值；
  digitalWrite(LED_YELLOW,distance>50 && distance<200);
  digitalWrite(LED_GREEN,distance>200 && distance<400);

  lcd.begin(16, 2);
  lcd.print(" Measured distance:   ");
  lcd.println(   readDistanceCM()  );

  //Serial.print("Measured distance: "); //串行监测器上所看到的测量数值
  //Serial.println(readDistanceCM());

  u8g.firstPage();

 if(distance<50) {
    do{
    u8g.drawStr(22, 20, "In your face!");
    u8g.setPrintPos(20,40);   //相当于lcd.setCursor(x,y)
    u8g.print("distance:");
    u8g.print(distance);
  }while ( u8g.nextPage() );
  }
 
  else if(distance>50&&distance<200){
    do{
    u8g.drawStr(15, 20, "It is coming close!");
    u8g.setPrintPos(20,40);   //相当于lcd.setCursor(x,y)
    u8g.print("distance:");
    u8g.print(distance);
    }while( u8g.nextPage() );
  }

  else{
    do{
    u8g.drawStr(25, 20, "Safe distance");
    u8g.setPrintPos(20,40);   //相当于lcd.setCursor(x,y)
    u8g.print("distance:");
    u8g.print(distance);
    }while( u8g.nextPage() );
  }
  delay(100);
}