How to send data from Arduino Nano 33 IoT to Matlab using UDP over WIFI

Hey,

I'm trying to send data from Arduino Nano 33 IoT (has WIFI chip) to Matlab using UDP. The gateway is the router. I wrote two codes for Arduino and Matlab but i'm geetting not data (ReplyBuffer).

IP-Adress from Arduino:

SSID: MagentaWLAN-6XU4
signal strength (RSSI):-62 dBm
Local IP: 192.168.2.50
Subnet Mask: 255.255.255.0
Gateway IP: 192.168.2.1

Matlab Code

remPort=8888;      
host='192.168.2.50';  
locPort=50001;
u = udp(host,'RemotePort',remPort,'LocalPort',locPort); 
fopen(u)
A = fread(u);
fclose(u)

Arduino Code:

#include <WiFi.h>
#include <WiFiUdp.h>

int status = WL_IDLE_STATUS;
char ssid[] = "MagentaWLAN-6XU4"; //  your network SSID (name)
char pass[] = "11980331210951165236";    // your network password (use for WPA, or use as key for WEP)
int keyIndex = 0;            // your network key Index number (needed only for WEP)
unsigned int localPort = 8888;
char  ReplyBuffer[] = { 2, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 



WiFiUDP Udp;

void setup() {

  Serial.begin(115200);
// einmaliger Gebrauch
  while (!Serial) {

    ; // wait for serial port to connect. Needed for native USB port only

  }

 
  String fv = WiFi.firmwareVersion();

  if (fv != "1.1.0") {

    Serial.println("Please upgrade the firmware");

  }

  // attempt to connect to Wifi network:

  while (status != WL_CONNECTED) {

    Serial.print("Attempting to connect to SSID: ");

    Serial.println(ssid);

    // Connect to WPA/WPA2 network. Change this line if using open or WEP network:

    status = WiFi.begin(ssid, keyIndex, pass);   // Das habe ich eingefügt

    // wait 10 seconds for connection:

    delay(10000);

  }

  Serial.println("Connected to wifi");

  printWifiStatus();

  Serial.println("\nStarting connection to server...");

  // if you get a connection, report back via serial:

  Udp.begin(localPort);
}

void loop() {

  

  int packetSize = Udp.parsePacket();

    // send a reply, to the IP address and port that sent us the packet we received

    Udp.beginPacket(Udp.remoteIP(), Udp.remotePort());
// da werden dann unsere Daten an Matlab geschikt
    Udp.write(ReplyBuffer);

    Udp.endPacket();
  
  }

The error I'm getting in Matlab:

  Warning: udp will be removed in a future release. Use udpport instead. 
Warning: Unsuccessful read:  The specified amount of data was not returned within the Timeout period.
'udp' unable to read any data. For more information on possible reasons, see UDP Read Warnings. 

and the Data (A) is empty.

Does someone see where is the Problem in the code?

[Walter Roberson]

For debugging purposes, connect to the serial port of the arduino, and after the Udp.begin() add another log message saying the connection was established. Then examine the output to try to figure out the stage the arduino is getting to.

[Ibrahim alami merroui]

I did what you suggested, I'm getting the message but i don't see the point.

I hope that you can be more specific about the solution to my code.

Thanks

[Walter Roberson]

I need to know what you saw on the serial port monitor. What did the arduino think was happening? In particular I need to know whether the arduino thought that it received an incoming packet.

[Walter Roberson]

https://arduino-esp8266.readthedocs.io/en/latest/esp8266wifi/udp-examples.html has information that should help in debugging. You want to track down whether the arduino thinks it is receiving a packet, and the monitor mentioned there should help figure out whether the reply is working. You need to distinguish between the reply not working at all, compared to something wrong on the matlab side that is preventing it from seeing the reply.

[Ibrahim alami merroui]

Thanks for the reply.

The message i'm getting is:

Please upgrade the firmware
Attempting to connect to SSID: MagentaWLAN-6XU4
Connected to wifi
SSID: MagentaWLAN-6XU4
IP Address: 192.168.2.50
signal strength (RSSI):-65 dBm
Local IP: 192.168.2.50
Subnet Mask: 255.255.255.0
Gateway IP: 192.168.2.1

Starting connection to server...
the connection was established

I did upgrade the Firmware and turn the fireware off in case this is the problem, but it didn't work.

The second thing I changed is this command :

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

to

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

and I gave in remoteIP the IP adress of the Gateway in matloab and Arduino IDE, but also didn't work.

I saw the code you sent, it says first of all Matlab will send a message then Arduino is just going to reply when a message has been recieved.

My code i wrote above sends a message and dosen't recieve anything.

I have maybe in this case some questions:

Wich port and IP adress schould i use for the transfer ?

Why i can't give the IP-Adress and the Port in UDPPORT() ?

I tried to write a code to use it with Arduino Code you suggested but it doesn't work :::(((

[Walter Roberson]

I would not worry about the firmware thing at the moment; the code is written in such a way that it would also complain if you had a newer firmware.

Have you tried using the packet generation program mentioned in https://arduino-esp8266.readthedocs.io/en/latest/esp8266wifi/udp-examples.html to see whether it can see a response? We need to distinguish between "no reply packet is really being generated" and "reply packet is generated but is sent to wrong place" and "reply packet is being correctly generated but MATLAB specifically is having problems with it"

[Ibrahim alami merroui]

thanks for the reply.

I couldn't upload the code you shared, but i have used this code Send and Receive UDP String | Arduino Documentation | Arduino Documentation. I think it does the same work. I downloaded the Packet Sender App for Windows. After I uploaded the sketch on Arduino IDE I sent directly a messag from the App and I got the reply.

Serial Monitor:

Starting connection to server...
Received packet of size 13
From 192.168.2.41, port 53988
Contents:
hello ibrahim

The problem i see that i can't make any communication beetween matlab and packet sender app. I used this code:

remPort=18;      
 host='192.168.2.50';  
 locPort=19;
 u = udp(host,'RemotePort',remPort,'LocalPort',locPort) 
 fopen(u)
 A = fread(u);
 write('hey');
 fclose(u)

I think i should use udpport() instead of udp. With this code i'm getting not packets or receiving it from the app.

If I use the port 53988 as remPort to send data, matlab says:

 Error using icinterface/fopen
Unsuccessful open: Address already in use: Cannot bind

In this case the reply packet is generated but is sent to wrong place and matlab can't receive anything.