ESP32 Forum

Posted: **Tue Jun 16, 2020 10:36 pm**

Hello everyone!

I am trying to find solution to my problem for few days but i almost gave up...

i try to set up communication via TCP/IP between few ESP32 modules, (1 is server and rest are clients sending data). I did it succesfully but when i try to recognize each ESP32 by IP (by calling client.remoteIP()) i got memory crash like this:
Guru Meditation Error: Core 0 panic'ed (InstrFetchProhibited). Exception was unhandled.
Core 0 register dump:
PC : 0x00000000 PS : 0x00060e30 A0 : 0x801100ad A1 : 0x3ffb3d30
A2 : 0x3ffccd7c A3 : 0x3ffccfb0 A4 : 0x3ffcb340 A5 : 0x3ffcb320
A6 : 0x0204a8c0 A7 : 0x0c04a8c0 A8 : 0x8010ff50 A9 : 0x3ffb3cf0
A10 : 0x3ffccd8c A11 : 0x3ffccfb0 A12 : 0x3ffb3d3c A13 : 0x00000044
A14 : 0x00000001 A15 : 0x00000006 SAR : 0x00000010 EXCCAUSE: 0x00000014
EXCVADDR: 0x00000000 LBEG : 0x4000c349 LEND : 0x4000c36b LCOUNT : 0x00000000

Backtrace: 0x00000000:0x3ffb3d30 0x401100aa:0x3ffb3d70 0x4011d011:0x3ffb3d90 0x40122019:0x3ffb3dd0 0x401272b6:0x3ffb3df0 0x401109cf:0x3ffb3e10 0x40088b7d:0x3ffb3e40

Like i said if i dont call for client.remoteIP function i am able to send data - but i need this to recognize every ESP and sord received data properly
When i call client.remoteIP() only once it works properly (but not always, sometimes i need to restart clients few times to stabilize)

I attach code for server:

Code: [Select all] [Expand/Collapse]

#include <WiFi.h>
 
WiFiServer server(80);                // Set a object server as a WiFiServer class
IPAddress IP(192,168,4,1);           // Select ip and mask
IPAddress mask = (255, 255, 255, 0);
 
void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_AP);                     // Set Wi-Fi as access point/server
  WiFi.softAP("ESP32", "123456789");                // SSID and Password for the AP
  WiFi.softAPConfig(IP, IP, mask);        // Set our own desired IP address
  server.begin();  // Begin the server
 
  Serial.println("Server started.");
  Serial.print("IP: ");   
  Serial.println(WiFi.softAPIP());        // .softAPIP calls for the IP of the access point which we set earlier
  Serial.print("MAC:");   
  Serial.println(WiFi.softAPmacAddress());  // Calls for the mac address
  }
 
void loop() {
  WiFiClient client = server.available(); // Return a client object to the class if there is a client available
  client.setNoDelay(1);
  if (!client) {return;}    // Return cuts the function (loop) if client class is not connected
 
//  String request = client.readStringUntil('\r');    // Reads string received until \r and saves as string
//  Serial.print("From ");
//  Serial.print(client.remoteIP());
//  Serial.print(", port ");
//  Serial.println(client.remotePort());
 
  if (client.remoteIP()[3] == 2){ // check the last byte of IP adress to check which esp connected
  String request = client.readStringUntil('\r');
  Serial.println(" Dostalem po TCP od 1 : " + request);                               
  client.println(" Dostalem po TCP: " + request + "\r");   // Send the data with the \r so the client knows when to stop
  }
 
    if (client.remoteIP()[3] == 3){
  String request = client.readStringUntil('\r');
  Serial.println(" Dostalem po TCP od 2 : " + request);                               
  client.println(" Dostalem po TCP: " + request + "\r");   // Send the data with the \r so the client knows when to stop
  }
    }

GeSHi © Codebox Plus Extension

and code for client:

Code: [Select all] [Expand/Collapse]

include <WiFi.h>
 
IPAddress ip(192, 168, 4, 1);
const char* host = "192.168.4.1"; 
const uint16_t port = 80;       
int buffer;     
int sygnal[100];  /
 
void setup()
{
  Serial.begin(115200);
  Serial.println();
  WiFi.begin("ESP32", "123456789");
  Serial.print("Connecting");
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected, IP address: ");
  Serial.println(WiFi.localIP());
  for (int i=0; i <100; i++){   
    sygnal[i]=i;
  }
  delay(2500);
}
void loop() {
  Serial.print("connecting to ");
  Serial.print(host);
  Serial.print(':');
  Serial.println(port);
 
  for (int i=0; i <100; i++){  //send 100 times
    buffer=sygnal[i];
  // Use WiFiClient class to create TCP connections
    WiFiClient client;
    if (!client.connect(host, port)) {
      Serial.println("connection failed");
      Serial.println("wait 3 sec...");
      delay(3000);
      return;
    }
    // send buffer to server
  client.print(buffer);
  client.println("\r");
  Serial.print("Wyslalem po TCP: ");
  Serial.println(buffer);
  //odczytaj odpowiedz serwera
  Serial.print("Odpowiedz: ");
  String line = client.readStringUntil('\r');
  Serial.println(line);
  Serial.println("closing connection");
  client.stop();
  }
//5 seconds delay
  Serial.println("wait 5 sec...");
  delay(5000);
}

GeSHi © Codebox Plus Extension

Maybe there is any working example of communications like this - with many ESP32, or maybe someone can give me a tip how to deal with it

Posted: **Wed Jun 17, 2020 2:46 am**

You will need to decode your backtrace using the tool at https://github.com/me-no-dev/EspExceptionDecoder .

Posted: **Wed Jun 17, 2020 8:16 am**

Hey, i did what u linked me and the result is:

Posted: **Wed Jun 17, 2020 8:55 am**

I updated result, in previous one i did mistake

Posted: **Wed Jun 17, 2020 2:04 pm**

I am unable to reproduce your problem, but it doesn't really look like it is the remoteIP call causing the crash.
Turn on Core Debug Level: Verbose to see if any additional information is available.
Put in more debug prints so you can see exactly where the error occurs (log_v is better for this than Serial.print)
This code works quite reliably for me without crash:

Code: Select all

void loop() {
  delay(100);
  WiFiClient client = server.available();
  if (!client) {return;}
  Serial.println(client.remoteIP()); 
}

ESP32 Forum

TCP/IP communication between few ESP32 - memory crash with client.remoteIP()

TCP/IP communication between few ESP32 - memory crash with client.remoteIP()

Re: TCP/IP communication between few ESP32 - memory crash with client.remoteIP()

Re: TCP/IP communication between few ESP32 - memory crash with client.remoteIP()

Re: TCP/IP communication between few ESP32 - memory crash with client.remoteIP()

Re: TCP/IP communication between few ESP32 - memory crash with client.remoteIP()