Ethernet

Projects Programming
1

Hey all!

So, I have two Arduino Megas both equipped with an ethernet shield 2. With that code I want to send a UDP Packet over the ethernet from the first Arduino, to tell the other Arduino it should or shouldnt switch on an LED if I push a button (I need to keep it pushed).
That works, but the problem I have is that it takes very very long...
When I upload the code and push the button it takes about a minute for the first Arduino to even register that I pushed the button. And it takes another thirty seconds or so to switch on or switch on the LED.
How can I speed that up?

Thank you very much!

Here`s the code:

#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
byte taster = A4;
byte power = 44;
byte tasterWert;
byte mac[] = {0xDE,0xAD,0xBE,0xEF,0xFE,0xED}; //dest mac address
IPAddress ip(); //Local
IPAddress destIp(); //dest

unsigned int localPort = 5000; //Local Port to listen on
unsigned int destPort = 5005; //dest port

EthernetUDP Udp; //Instance
char high [] = "H";
char low [] = "L";

void setup(){
pinMode(taster,INPUT);
pinMode(power,OUTPUT);
Ethernet.begin(9600);
Udp.begin(localPort);
Serial.begin(9600);

}

void loop() {
digitalWrite(power,HIGH);
int tasterWert = digitalRead(taster);
Serial.println(tasterWert);
Udp.beginPacket(destIp, destPort);

if(tasterWert == 1){
Udp.write(high);
}
Udp.endPacket();

Udp.beginPacket(destIp, destPort);

if(tasterWert == 0){
Udp.write(low);
}
Udp.endPacket();

}

2

Ethernet.begin(9600); ???

3

@Juraj

Yeah I found that one!
But the problem continues...

Now it just prints a 0 and after this, nothing...

But thanks for the reply

4

sevizimmi:
@Juraj

Yeah I found that one!
But the problem continues...

Now it just prints a 0 and after this, nothing...

But thanks for the reply

this is a setup with a cable between two shields? or you have a router which assignes IP addresses.

5

@Juraj

Yes, I have a router.

6 
char high [] = "H";
char low [] = "L";

It's rather pointless to use char arrays to hold one letter.

Yeah I found that one!

And, you did what? If you changed the code, you can't expect us to guess how.

 Udp.beginPacket(destIp, destPort);

 if(tasterWert == 1){
   Udp.write(high);
 }
 Udp.endPacket();

 Udp.beginPacket(destIp, destPort);

 if(tasterWert == 0){
   Udp.write(low);
 }
 Udp.endPacket();

Regardless of what came in, send two packets, one of which is empty. That is NOT the right thing to do.

7

is the router connected to Internet? can you try the WebClient example?
do you use the latest version of the Ethernet iibrary?

8

@Juraj

Yes it is connected. The example works perfect :slight_smile:

9

do you use the same MAC address on both shields?

10

@Juraj

No they are different, this is the other one btw:

#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
#define W5200_CS_ 10
byte LED = 6;
byte mac[] = {0x90,0xA2,0xDA,0x10,0x5F,0x92};
IPAddress ip();

unsigned int localPort = 5005;

char packetBuffer[UDP_TX_PACKET_MAX_SIZE];
char ReplyBuffer []= "has agstellt";

EthernetUDP Udp;

void setup(){
pinMode(LED,OUTPUT);
Ethernet.begin(mac,ip);
Udp.begin(localPort);
Serial.begin(9600);
}

void loop(){
int packetSize = Udp.parsePacket();
if(packetSize){
Udp.read(packetBuffer,UDP_TX_PACKET_MAX_SIZE);
packetBuffer[packetSize] = '\0';
packetSize -= 8;
Serial.print("Received packet data size = ");
Serial.print(packetSize);
Serial.print(" from ");
IPAddress remote = Udp.remoteIP();
for (int i = 0; i < 4; i++) { // Print IP address xxx.xxx.xxx.xxx
Serial.print(remote*, DEC);*

  • if (i < 3) {*

  • Serial.print(".");*

  • }*

  • }*

  • Serial.print(", port");*

  • Serial.println(Udp.remotePort());*

  • // Udp.read(packetBuffer,UDP_TX_PACKET_MAX_SIZE);*

  • Serial.println("contents");*

  • Serial.println(packetBuffer);*

  • Udp.beginPacket(Udp.remoteIP(),Udp.remotePort());*

  • Udp.write(ReplyBuffer);*

  • Udp.endPacket();*

  • switch (packetBuffer[0]) {*

  • case 'H':*

  • digitalWrite(LED,HIGH);*

  • break;*

  • case 'L':*

  • digitalWrite(LED,LOW);*

  • break;*

  • }*

  • delay(10);*
    }
    }

11

do you set the IP or is it set by DHCP? do the default gateway and subnetmask match your network?

12

@Juraj

Its over IP and I didnt have defined a subnet mask or gateway.

13

sevizimmi:
@Juraj

Its over IP and I didnt have defined a subnet mask or gateway.

do the default gateway and subnetmask match your network?

the library uses first 3 numbers of IP address with 1 as 4 number for the address of the gateway and dns server and network mask 255.255.255.0

14

@Juraj

Yes they are :slight_smile:

15

then see the comment of PaulS. you send empty packets. and too many packets.

16

@PaulS

Hey there, I just changed it from Ethernet.begin to Udp.begin(localPort);

And what do you mean with empty packet? How should I change that?

Thank you

17

And what do you mean with empty packet?

YOU need to research what Udp.beginPacket(), Udp.write(), and Udp.endPacket() do.

How should I change that?

Do NOT call beginPacket() and endPacket() unconditionally, while the write()(s) are conditional.