Arduino+ds18b20 temperature sensor (buzzer alarm) +lcd1602 display (IIC drive)

Experimental equipment

arduino mega2560(uno And other series are the same ）

ds18b20 Temperature sensor （ Waterproof package ）

lcd1602A （ save io mouth , external pcf8574, Four wire drive ）

There are several DuPont lines

Introduce

ds18b20

characteristic ： Wide voltage range ,3.0~5.5v, Single line transmission of data , Multiple temperature sensors can be connected on three lines , Multi point temperature measurement , When the positive and negative poles are reversed for a short time , Will not burn the chip , But it doesn't work .
Measuring temperature range ：-55℃~+125℃
Programmable resolution ,9 A to 12 position , Respectively 0.5℃,0.25℃,0.125℃,0.0625℃. Default 12 Bit accuracy
ds18b20, There is an external terminal adapter , If there is no terminal adapter connected externally at the data end 1k The pull-up resistance of about Ω is enough （ The chip resistor on the module is only used 472 o ）

Call library , The simple function program is as follows
The same is true for references after adding other libraries

Code segment

#include <OneWire.h>       
#include <LiquidCrystal_I2C.h>    //4 The needle pcf8574 drive lcd1602 library 
#include <DallasTemperature.h>   //ds18b20 library 
#define buzzpin 6      // Define buzzer 6 Pin No 
#define Onewire_bus 7     //ds18b20 Connect 7 Pin 
OneWire oneWire(Onewire_bus);
DallasTemperature sensors(&oneWire);
LiquidCrystal_I2C lcd(0x27,16,2);     //LCD1602 Of I2C The address is 0x27,LCD1602 Two lines , Each row 16 Character LCD 
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  lcd.init(); //  Perform twice LCD Of I2C Communication initialization 
  delay(20);
  lcd.init();
  delay(20);
  lcd.backlight();// Lighten up LCD Backlight 
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(50);
  Serial.print(" Get the temperature ：");    //  Send a few words 
  sensors.requestTemperatures();         // Get the temperature 
  Serial.println(sensors.getTempCByIndex(0));
  lcd.setCursor(0, 0);               //  take LCD The cursor moves to the first position 0,0( Column , That's ok )
  lcd.print("temp:");
  lcd.print(sensors.getTempCByIndex(0));    //  Sensor temperature value 
  lcd.print(" C");            //  Continue the previous statement to write 
  if(sensors.getTempCByIndex(0)>40)    // The temperature is greater than 40 Call the police 
  {
    digitalWrite(buzzpin,HIGH);
   }
   else
   {
    digitalWrite(buzzpin,LOW);
    }
    delay(10);
}

test

There is no water here , Simple touch temperature test
Serial port display

if lcd1602IIC The address is not 0x27, You can find it through the following program , Serial port sending address

#include <Wire.h> 

void setup() {
    Serial.begin (115200);  
    while (!Serial) { } 
    Serial.println (); 
    Serial.println ("I2C scanner.Scanning ..."); 
    byte count = 0; 
    Wire.begin(); 
    for (byte i = 8; i < 120; i++) {
        Wire.beginTransmission (i);
        if (Wire.endTransmission () == 0) {
            Serial.print ("Found address: ");
            Serial.print (i, DEC); Serial.print (" (0x");
            Serial.print (i, HEX); Serial.println (")");
            count++; delay (1); // maybe unneeded?
        } // end of good response
    } // end of for loop 
    Serial.println ("Done."); 
    Serial.print ("Found "); 
    Serial.print (count, DEC); 
    Serial.println (" device(s)."); 
} // end of setup 

void loop() {}

（ source csdn, I can't find the original article of the boss , Invasion and deletion ）

Have a problem

IIC Wrong address
Welded pcf8574 There is a potentiometer behind the adapter board , If the serial port displays the value normally ,lcd If it is not shown, you can adjust the potentiometer ,lcd After brightness adjustment, it can be displayed