Arduino-esp32: ESP32 guru meditation error while connecting to AP

Created on 6 Jan 2019 · 6Comments · Source: espressif/arduino-esp32

Hardware:

Board: ESP 32 DEVKIT v1
Core Installation/update date: 21/10/2018
IDE name: Arduino IDE
Flash Frequency: 80Mhz
Upload Speed: 9600
Computer OS: Windows 10/7

Description:

I have set up an Acess point on ESP 32. It is successfully configuring. But, while trying to connect to access point I am getting Guru meditation exception

Sketch:

#include <WiFi.h>
#include "SPIFFS.h"
#include <EEPROM.h>
#include <WebServer.h>
#include <DNSServer.h>
#define EEPROM_SIZE 512
WebServer server(80);
const byte DNS_PORT = 53;
DNSServer dnsServer;
//*********SSID and Pass for AP**************/
const char *ssidAP = "ESPuser";
//********** Variable for SSID and Pass*************/
String STATION_SSID; 
String STATION_PASSWORD;
String DEVICE_ID;
String HOST_ID;
//*********Static IP Config**************/
IPAddress ap_local_IP(192,168,1,4);
IPAddress ap_gateway(192,168,1,254);
IPAddress ap_subnet(255,255,255,0);
//*********AP Timer**************/
unsigned long apTimer =0;
unsigned long apInterval = 120000;

void setup()
{
  Serial.begin(9600); 
  while(!Serial);
  WiFi.mode(WIFI_AP);
  Serial.println(WiFi.softAPConfig(ap_local_IP, ap_gateway, ap_subnet) ? "access point onfigured...":"Not connected");
  Serial.print("Setting soft-AP ... ");
  Serial.println(WiFi.softAP(ssidAP) ? "SoftAp Setup": "Failed to connect");
  dnsServer.start(DNS_PORT, "*", ap_local_IP);
  if (!EEPROM.begin(EEPROM_SIZE))
  {
    Serial.println("failed to initialise EEPROM"); 
  }
  SPIFFS.begin();
  server.on("/", handleRoot);
  server.begin();
  apTimer = millis();
  while(millis()-apTimer<= apInterval) {
         dnsServer.processNextRequest();
        server.handleClient();  }
  InitWifi();
  }
void loop()
{    }
////**************Connect to local WiFi************/
void InitWifi(){
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
        char ssid[30];  char pass[30];char device[30];
        String string_Ssid= read_string(30,0); 
        String string_Password= read_string(30,60);
        String device_id =  read_string(30,120);
        string_Ssid.toCharArray(ssid,sizeof(string_Ssid)+1);
        string_Password.toCharArray(pass,sizeof(string_Ssid)+1);
        device_id.toCharArray(device,sizeof(string_Ssid)+1);
        Serial.println("ssid: "+ string_Ssid);
        Serial.println("Password: "+ string_Password);
  WiFi.begin(ssid,pass);
  while (WiFi.status() != WL_CONNECTED)
  {   delay(500);
      Serial.print(".");
  }
  Serial.println(WiFi.localIP());
 }
//****************************HANDLE ROOT***************************//
void handleRoot() {
   if (server.hasArg("ssid")&& server.hasArg("password") && server.hasArg("device") && server.hasArg("connect") ) {
    handleSubmit();
  }
  else {File  file = SPIFFS.open("/webform.html", "r");
      server.streamFile(file,"text/html");
      file.close();
   }
}

//**************************SUBMIT RESPONSE**************************//
void handleSubmit(){//dispaly values and write to memmory
 String response="<p>The ssid is ";
 response += server.arg("ssid");
 response +="<br>";
 response +="And the password is ";
 response +=server.arg("password");
 response +="<br>";
 response +="the Connection String is ";
 response +=server.arg("connect");
 response +="<br>";
 response +="the device Id is ";
 response +=server.arg("device");
 response +="</P><BR>";
 response +="<H2><a href=\"/\">go home</a></H2><br>";
 server.send(200, "text/html", response);

 ROMwrite(String(server.arg("ssid")),String(server.arg("password")), String(server.arg("device")));
 ROMconnectWrite(String(server.arg("connect")));
 }
//**************WRITE Connect String TO EEPROM******************//
void ROMconnectWrite(String conn){
 conn+="!";
 write_EEPROM(conn,200);
 EEPROM.commit();   
}
//**************WRITE RESPONSE TO EEPROM******************//
void ROMwrite(String s, String p, String d){
 s+=";";
 write_EEPROM(s,0);
 p+=";";
 write_EEPROM(p,60);
 d+=";";
 write_EEPROM(d,120);
}
//******************WRITE TO EEPROM**********************//
void write_EEPROM(String x,int pos){
  for(int n=pos;n<x.length()+pos;n++){
     EEPROM.write(n,x[n-pos]);
  }
   EEPROM.commit();   
}
//*****************READ STRING**********************//
String read_string(int l, int p){
  String temp;
  for (int n = p; n < l+p; ++n)
    {
     if(char(EEPROM.read(n))!=';'){
       temp += String(char(EEPROM.read(n)));
     }else n=l+p;
    }
  return temp;
}
//*****************READ CONN STRING**********************//
String read_conn_string(int l, int p){
  String temp;
  for (int n = p; n < l+p; ++n)
    {
     if(char(EEPROM.read(n))!='!'){
       temp += String(char(EEPROM.read(n)));
     }else n=l+p;
    }
  return temp;
}

Debug Messages:

Guru Meditation Error: Core  1 panic'ed (InstrFetchProhibited). Exception was unhandled.
Core 1 register dump:
PC      : 0x00000000  PS      : 0x00060430  A0      : 0x800fc409  A1      : 0x3ffb5670  
A2      : 0x3ffbbc90  A3      : 0x3ffbcf6c  A4      : 0x3ffbb9c8  A5      : 0x3ffbb954  
A6      : 0x0501a8c0  A7      : 0x0f01a8c0  A8      : 0x800fc2a8  A9      : 0x3ffb5630  
A10     : 0x3ffbbca0  A11     : 0x3ffbcf6c  A12     : 0x3ffb567c  A13     : 0x00000044  
A14     : 0x00000001  A15     : 0x00000006  SAR     : 0x00000010  EXCCAUSE: 0x00000014  
EXCVADDR: 0x00000000  LBEG    : 0x4000c349  LEND    : 0x4000c36b  LCOUNT  : 0x00000000  

Backtrace: 0x00000000:0x3ffb5670 0x400fc406:0x3ffb56b0 0x40104389:0x3ffb56d0 0x40106f35:0x3ffb5710 0x4010cede:0x3ffb5730 0x400fb805:0x3ffb5750

Decoded Messages:

PC: 0x00000000
EXCVADDR: 0x00000000

Decoding stack results
0x400fc406: handle_dhcp at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/apps/dhcpserver.c line 1035
0x40104389: udp_input at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/core/udp.c line 417
0x40106f35: ip4_input at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/core/ipv4/ip4.c line 705
0x4010cede: ethernet_input at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/netif/ethernet.c line 176
0x400fb805: tcpip_thread at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/api/tcpip.c line 143

Webform:

<!DOCTYPE HTML>
<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="content-type">
<meta name = "viewport" content = "width = device-width, initial-scale = 1.0, maximum-scale = 1.0, user-scalable=0">
<title>Mesh</title>
<style>
body { background-color: #F7F9F9  ; font-family: Arial, Helvetica, Sans-Serif; Color: #000000; }
input[type=text], select {
    width: 100%;
    padding: 12px 20px;
    margin: 8px 0;
    display: inline-block;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
}
</style>
</head>
<body>
<center>
<h1 style="color:#3498DB; font-family:verdana">WebCzar</h1>
<h2 style="color:#3498DB; font-family:Times New Roman">Enter Your User credentials</h2>
<FORM action="/" method="post">
<P>
<label style="font-family:Times New Roman"><b>SSID</b></label><br>
<input maxlength="30" name="ssid"><br>
</P>
<P>
<label style="font-family:Times New Roman"><b>PASSWORD</b></label><br>
<input maxlength="30" name="password"><br>
</P>
<INPUT type="submit" value="Submit your form"> 
<style>
input[type="submit"]{
    background-color: #3498DB; /* Green */
    border: none;
    color: white;
    padding: 15px 32px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 16px;
}
</style>
<INPUT type="reset">
<style>
input[type="reset"]{
    background-color: #3498DB; /* Green */
    border: none;
    color: white;
    padding: 15px 32px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 16px;
}
</style>

</FORM>
</center>
</body>

Source

vbshightime

Most helpful comment

I also ran into this problem. My solution was to call WiFi.softAP(WIFI_SSID, WIFI_PASSWORD) and then WiFi.softAPConfig(local_IP, gateway, netmask).
Changing the sequence will reproduce the exception on my system.

siochs on 14 Jan 2019

👍2

All 6 comments

I am not frequently getting this exception. But sometimes when the esp32 is getting an inadequate power supply or it is getting warm the exception occurs. I have no clue why this is happening. One more thing, you can see it in code that I have configured a static IP but still, ESP32 connects to DHCP or it's default IP (192.168.4.1). I have resolved this issue by applying this fix to my code

  while(!(WiFi.softAPIP()== ap_local_IP)){
    WiFi.softAPConfig(ap_local_IP, ap_gateway, ap_subnet);    
}

Serial.println(WiFi.softAP(ssidAP) ? "soft-AP setup": "Failed to connect");

Serial.println(WiFi.softAPIP());`

yeah it showed some effective results but I'm still getting this exception once a while

vbshightime on 10 Jan 2019

👍1

siochs on 14 Jan 2019

👍2

Thanks for your suggestion @siochs. I did the same thing to resolve my problem. Now I am not getting this exception

vbshightime on 15 Jan 2019

I'm running into the same issue on what appears to be a different version of the idf (line numbers are changed but similar). Changing the order of the softAP andn softAPConfig calls makes no difference.

Decoded backtrace:

0x4010c7a2: handle_dhcp at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/apps/dhcpserver/dhcpserver.c line 1031
0x40119281: udp_input at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/lwip/src/core/udp.c line 401
0x4011cc19: ip4_input at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/lwip/src/core/ipv4/ip4.c line 740
0x40121e4e: ethernet_input at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/lwip/src/netif/ethernet.c line 184
0x4010f77f: tcpip_thread at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/lwip/lwip/src/api/tcpip.c line 135
0x4008f2ad: vPortTaskWrapper at /Users/ficeto/Desktop/ESP32/ESP32/esp-idf-public/components/freertos/port.c line 143

treii28 on 28 Mar 2019

Are you frequently getting this issue. Sometimes the device tries to connect to the DHCP IP or it's default IP(192.168.4.1) even when you have configured the AP. S if changing the sequence doesn't works then try WiFi.disconnect() first and then insert following check

    while(!(WiFi.softAPIP()== ap_local_IP)){
          WiFi.softAPConfig(ap_local_IP, ap_gateway, ap_subnet);    
          }
              Serial.println(WiFi.softAP(ssidAP) ? "soft-AP setup": "Failed to connect");
              Serial.println(WiFi.softAPIP());

vbshightime on 10 Apr 2019

Are you frequently getting this issue. Sometimes the device tries to connect to the DHCP IP or it's default IP(192.168.4.1) even when you have configured the AP. S if changing the sequence doesn't works then try WiFi.disconnect() first and then insert following check
    while(!(WiFi.softAPIP()== ap_local_IP)){
          WiFi.softAPConfig(ap_local_IP, ap_gateway, ap_subnet);    
          }
              Serial.println(WiFi.softAP(ssidAP) ? "soft-AP setup": "Failed to connect");
              Serial.println(WiFi.softAPIP());

i am still getting this error. i already applied thes lines of code but this didn't solve my problem