public class Main
{
    Thread t1,t2;
    Ausgabe aus_1;
    Ausgabe aus_2;
    public Main()
    {
    }
    
    public void initialisieren()
    {
        Sema sema = new Sema();
        aus_1= new Ausgabe("ABCD",500,sema);
        aus_2 = new Ausgabe("123",500,sema);
        t1 = new Thread(aus_1);
        t2 = new Thread(aus_2);
         t1.start();
         t2.start();
    }
    public static void main()
    {
        // tragen Sie hier den Code ein
        Main main = new Main();
        main.initialisieren();
    }
}

Code 0-1: Main.java

public class Ausgabe implements Runnable 
{
    private String ausgabe = "Tschüss";
    private long pausenlaenge;
    private Sema sema;
    public Ausgabe(String text, long pausenlaenge, Sema sema)
    {
        // Instanzvariable initialisieren
        this.pausenlaenge = pausenlaenge;
        //this.ausgabe = text;
        ausgabe = text;
        this.sema = sema;
    }

    public void run()
    {
      while(true)
      {
        if(sema.warte())
        {
          for (int i =0;i<ausgabe.length();i++)
          {
              System.out.print(ausgabe.charAt(i));
              if(i==ausgabe.length()-1)
                 sema.signal();
              try
              {
                  Thread.sleep(pausenlaenge);
              }
              catch(Exception e)               
              {
                  System.out.println("Pommes");
              }
          
          }
          //sema.signal();
        }  
      }
    }
}

Code 0-2: Ausgabe.java

public class Sema
{
    private boolean zustand;
    public Sema()
    {
         zustand = true;
    }
    public synchronized boolean warte() //wait im Text
    {
         if(zustand==true) // if device available
         {
             zustand = false;
             return true; //it worked, you have access to device 
         }
         else
         {
             return false; //it did not work
         }
    }    
    public synchronized boolean signal()
    {
         if(zustand==false) 
         {
              zustand = true;
              return true; //it worked to return the device
         }
         else
         {
              return false; 
         }
         
    }
}

Code 0-3: Sema.java

#include <Arduino_FreeRTOS.h>

// define two tasks for Blink & AnalogRead
void Task1( void *a );
void Task2( void *b );
char str1[]="Hello";
char str2[]="Bye";
int x=1;

int MAX1 = 0;
int MAX2 = 0;

// the setup function runs once when you press reset or power the board
void setup() {
  
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
  
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB, on LEONARDO, MICRO, YUN, and other 32u4 based boards.
  }

  // Now set up two tasks to run independently.
  xTaskCreate(
    Task1
    ,  (const portCHAR *)"Hello"   // A name just for humans
    ,  128  // This stack size can be checked & adjusted by reading the Stack Highwater
    ,  NULL
    ,  0 // Priority, with 3 (configMAX_PRIORITIES - 1) being the highest, and 0 being the lowest.
    ,  NULL );

  xTaskCreate(
    Task2
    ,  (const portCHAR *) "Bye"
    ,  128  // Stack size
    ,  NULL
    ,  0 // Priority
    ,  NULL );

  // Now the task scheduler, which takes over control of scheduling individual tasks, is automatically started.
}

void loop()
{
  // Empty. Things are done in Tasks.
}

void Task1(void *a)  // This is a task.
{
  (void) a;
  for (;;)
  {
    if (x==1)
    {
      x=0;
      MAX1=strlen(str1);
    }  
    else
    {
      MAX1=0;  
    }
    
    for (int i=0;i<MAX1;i++)
    {    
      Serial.println(str1[i]);
      vTaskDelay(10);
    }
 
    if (MAX1>0)  
    { 
      x=1;
      vTaskDelay(200);
    }
      
  }
}


void Task2(void *b)  // This is a task.
{
  (void) b;
  for (;;)
  {
    if (x==1)
    {
      x=0;
      MAX2=strlen(str2);
    }  
    else
    {
      MAX2=0;  
    }
    
    for (int i=0;i<MAX2;i++)
    {    
      Serial.println(str2[i]);
      vTaskDelay(10);
    }
 
    if (MAX2>0)  
    { 
      x=1;
      vTaskDelay(200);
    }
      
  }
}

Code 0-4: Studentische Lösung "Binäre Semaphore mit Arduino".

PC: AUSGABE ifconfig
wlp3s0    Link encap:Ethernet  HWaddr f8:16:54:64:b8:f1  
          inet addr:192.168.1.252  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::1aa5:f936:9187:c977/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2001 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2372 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:170615 (170.6 KB)  TX bytes:276791 (276.7 KB)

Processing-Sketch am PC:
-- UDP session started at Mon Oct 21 15:55:41 CEST 2019 --
-- bound socket to host:null, port: 6000 --
[19-10-21 15:55:51.754 +0200] send packet -> address:/192.168.1.135, port:6100, length: 3
[19-10-21 15:55:52.147 +0200] receive packet <- from /192.168.1.135, port:6100, length: 12
receive: "acknowledg" from 192.168.1.135 on port 6100
[19-10-21 15:55:54.821 +0200] send packet -> address:/192.168.1.135, port:6100, length: 3
[19-10-21 15:55:55.55 +0200] receive packet <- from /192.168.1.135, port:6100, length: 12
receive: "acknowledg" from 192.168.1.135 on port 6100
[19-10-21 15:56:02.305 +0200] send packet -> address:/192.168.1.135, port:6100, length: 3
[19-10-21 15:56:02.335 +0200] receive packet <- from /192.168.1.135, port:6100, length: 12
receive: "acknowledg" from 192.168.1.135 on port 6100

Serial-Monitor (Ausgabe vom Arduino nano 33 IoT, Tasten a,b,c im Processing Sketch gedrückt):
Attempting to connect to SSID: ZTE A2017G_2064

Connected to wifi

SSID: ZTE A2017G_2064

IP Address: 192.168.1.135

signal strength (RSSI):-51 dBm


Starting connection to server...

Received packet of size 3

From 192.168.1.252, port 6000

Contents:

a;


Received packet of size 3

From 192.168.1.252, port 6000

Contents:

b;


Received packet of size 3

From 192.168.1.252, port 6000

Contents:

c;

Code 0-5: Ausgaben der verschiedenen Hardware-Komponenten.

//HILFESTELLUNG mit Quelltext:

//ArrayList anlegen:
ArrayList<iGeometrie> arr = new ArrayList<iGeometrie>();

//Neues Objekt in Array-List hinzufügen:
arr.add(new Kreis(mouseX,mouseY));

//Abrufen und zeichnen der in arr gespeicherten Objekte:
for(int i=0;i<arr.size();i++)
{
    iGeometrie g = arr.get(i);
    g.draw();
}

Code 0-6: Beispielcode als Hilfe