Arduino UNO r3+LCD1602+DHT11

In order to save the cost of the board IO The four wire drive display connection used for the display here , Display the used LiquidCrystal library , The library can be installed directly from

IDE Under the item option in include Library Choose from manage library Mid search LCD, Install the necessary library files . It can also be in github Download zip Package to install ,URL：http://https://github.com/adafruit/Adafruit_LiquidCrystal

Code ：

#include <LiquidCrystal.h>

// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);


int temp;// temperature 
int humi;// humidity 
int tol;// Proofreading code 
int j;
unsigned int loopCnt;
int chr[40] = {0};// Create a numeric array , For storage 40 individual bit
unsigned long time;
#define pin 8


void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
 //lcd.print("hello, world!");

 Serial.begin(9600);

  
}

void loop() {
 bgn:
  delay(2000);
// Set up 2 No. interface mode is ： Output 
// Output low level 20ms（>18ms）
// Output high level 40μs
  pinMode(pin,OUTPUT);
  digitalWrite(pin,LOW);
  delay(20);
  digitalWrite(pin,HIGH);
  delayMicroseconds(40);
  digitalWrite(pin,LOW);
// Set up 2 No. 1 interface mode ： Input 
  pinMode(pin,INPUT);
  // High level response signal 
  loopCnt=10000;
  while(digitalRead(pin) != HIGH)
  {
    if(loopCnt-- == 0)
    {
// If it does not return to high level for a long time , Output a prompt , Start over .
      Serial.println("HIGH");
      goto bgn;
    }
  }
  // Low level response signal 
  loopCnt=30000;
  while(digitalRead(pin) != LOW)
  {
    if(loopCnt-- == 0)
    {
// If it does not return to low level for a long time , Output a prompt , Start over .
      Serial.println("LOW");
      goto bgn;
    }
  }
// Start reading bit1-40 The numerical   
    for(int i=0;i<40;i++)
  {
    while(digitalRead(pin) == LOW)
    {}
// When a high level occurs , Write down the time “time”
    time = micros();
    while(digitalRead(pin) == HIGH)
    {}
// When a low level appears , Write down the time , Then subtract the stored time
// If the value obtained is greater than 50μs, Then for ‘1’, Otherwise ‘0’
// And store it in the array 
    if (micros() - time >50)
    {
      chr[i]=1;
    }else{
      chr[i]=0;
    }
  }
   
// humidity ,8 Bit bit, Convert to numeric 
humi=chr[0]*128+chr[1]*64+chr[2]*32+chr[3]*16+chr[4]*8+chr[5]*4+chr[6]*2+chr[7];
   
// temperature ,8 Bit bit, Convert to numeric 
temp=chr[16]*128+chr[17]*64+chr[18]*32+chr[19]*16+chr[20]*8+chr[21]*4+chr[22]*2+chr[23];
  // Proofreading code ,8 Bit bit, Convert to numeric 
tol=chr[32]*128+chr[33]*64+chr[34]*32+chr[35]*16+chr[36]*8+chr[37]*4+chr[38]*2+chr[39];
// Output ： temperature 、 humidity 、 Proofreading code 
  if(tol >= humi + temp){
  Serial.print("temp:");
  Serial.println(temp);
  Serial.print("humi:");
  Serial.println(humi);
  Serial.print("tol:");
  Serial.println(tol); 
}else{
  Serial.println("error!");
  // Proofreading code , I don't use it here -
  // Theoretically , humidity + temperature = Proofreading code 
  // If the values are not equal , It indicates that the data read is wrong .
}


 lcd.clear();
    lcd.setCursor(0,0);
    lcd.print("Tem(");
    lcd.print((char)223);// Show o Symbol 
    lcd.print("C):");
    lcd.setCursor(8,0);   
  lcd.print(temp);
  
    lcd.setCursor(0,1);
    lcd.print("Hum(");
    lcd.print((char)37);// Show % Symbol 
    lcd.print("):");
    lcd.setCursor(7,1);
  lcd.print(humi);
}