Cet exemple illustre l’utilisation d’un capteur de température Dallas 1821, d’un écran LCD et du module Xbee.

Le code n’est pas factorisé, il est livré tel quel après quelques tests.

Code :

    #include <SoftwareSerial.h>
    #include <OneWire.h>

    // DS1821 on digital pin 2 external
    OneWire ds(2); 

    // DS1821 on digital pin 8 internal
    OneWire ds1(8); 

    // LCD on digital pin 6 et 7
    SoftwareSerial LCD(6, 7);

    // LCD on digital pin 6 et 7
    SoftwareSerial XBEE(3, 4);

    int led = 13;

    void setup(void)
    {
    LCD.begin(9600);
    XBEE.begin(57600);
    Serial.begin(9600); 

    //start 1821 conversion external
    ds.reset();
    ds.write(0xEE);

    //start 1821 conversion internal
    ds1.reset();
    ds1.write(0xEE);

    pinMode(led, OUTPUT);
    digitalWrite(led,LOW);
    }

    void loop(void){
    // external
    byte temp_;
    byte r;
    byte t;
    int i;
    byte present;

    // internal
    byte temp1_;
    byte r1;
    byte t1;
    int i1;
    byte present1;

    digitalWrite(led,LOW);
    delay(1000);

    // Read value external
    present = ds.reset();
    ds.reset();
    ds.write(0xAA); 
    temp_ = ds.read();

    // Read value internal
    present1 = ds1.reset();
    ds1.reset();
    ds1.write(0xAA); 
    temp1_ = ds1.read();

    //start 1821 conversion external
    ds.reset();
    ds.write(0xEE);

    //start 1821 conversion internal
    ds1.reset();
    ds1.write(0xEE);

    // negative temp external
    if (temp_ >> 7 == 1){ 
        r = temp_ ^ 0xFF; // bit inversion external
        t = r + 1;        // external

        Serial.print("T");
        Serial.print("-");
        Serial.print(t);
        Serial.print("C");

        LCD.print("?f");
        LCD.print("Text-");
        LCD.print(t);
        LCD.print("C");

        XBEE.print("T");
        XBEE.print("-");
        XBEE.print(t);
        XBEE.print("C"); 
    }
    // positive temp external
    else  
    {
        t = temp_; // external

        Serial.print("T");
        Serial.print("+");
        Serial.print(t);
        Serial.print("C");

        LCD.print("?f");
        LCD.print("Text+");
        LCD.print(t);
        LCD.print("C");

        XBEE.print("T");
        XBEE.print("+");
        XBEE.print(t);
        XBEE.print("C");
    }
        // negative temp internal
    if (temp1_ >> 7 == 1){ 
        r1 = temp1_ ^ 0xFF; // bit inversion external
        t1 = r1 + 1;        // external

        Serial.print("-");
        Serial.print(t1);
        Serial.print("C");

        LCD.print("?n");
        LCD.print("Tint-");
        LCD.print(t1);
        LCD.print("C");

        XBEE.print("-");
        XBEE.print(t1);
        XBEE.print("C"); 
    }
    // positive temp internal
    else  
    {
        t1 = temp1_; // internal

        Serial.print("+");
        Serial.print(t1);
        Serial.print("C");

        LCD.print("?n");
        LCD.print("Tint+");
        LCD.print(t1);
        LCD.print("C");

        XBEE.print("+");
        XBEE.print(t1);
        XBEE.print("C");
    }
    digitalWrite(led,HIGH);
    delay(1000); // default 500
    }