WiFi client hangs on reconnect/wifi lost

[Toshik]

If ESP tries to send something over WiFi while WiFi network suddenly switches of, there is 99% chance to hang ESP.
I use following code to debug with Socket Test Tool (http://sourceforge.net/projects/sockettest/):

void loop() {
    delay(10);

    if (WiFi.status() == WL_CONNECTED)
    {
        Serial.print("test wf: ");
        Serial.println(counter++);
        int connected = wifiClient.connected();
        if (connected)
        {
            Serial.println("test wf: sending");
            wifiClient.write("0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\r\n", 132);
            wifiClient.flush();
            Serial.println("test wf: sent");
        }
        else
        {
            Serial.println("test wf: connecting");
            wifiClient.connect(SOCKET_SERVER_IP_ADDRESS, 21);
        }

        Serial.println("test wf: done");
    }
}

I got following output:

test wf: 240
test wf: sending
test wf: sent
test wf: done
test wf: 241
test wf: sending
beacon timeout
rm match
pm close 7 0 0/21552041

 ets Jan  8 2013,rst cause:4, boot mode:(1,6)

wdt reset

After that ESP can be reset only by hardware button.

[Toshik]

Why it at least does not reboots? It is very bad behavior...

[Links2004]

check you hardware (GPIO) setup.
https://github.com/Links2004/Arduino#minimal-hardware-setup-for-bootloading-and-usage

boot mode:(1,6) indicates there is something wrong with GPIO0

[tontito]

My usb ttl adaptor
http://www.ebay.com/itm/291297582006?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

don't DTR and RST pin

GPIO0 button to GND and manuel firmware mode resetting push button

[Links2004]

for normal boot GPIO0 need to be High.
the watchdog get triggerd the chip reboots and check the GPIO0:
low --> bootloader mode (no start of application)
high --> normal boot to setup()

GPIO0 shut only be low (GND) if you want to upload new software in all other cases it need an pullup

[Blastersky]

I have the same problem. The code I'm showing below wokr's great until I do not reboot router.

I have tried many ways to jump over this issiue, like rebooting the ESP8266, but no luck so far. :(

Any ideas?

      if (client.connected() != 1 || WiFi.status() != WL_CONNECTED)
      {
         ESP.reset(); 
      }

Complete code:

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include "DHT.h"

#define DHTPIN 2     // what pin we're connected 
#define DHTTYPE DHT22   // DHT 22  (AM2302)
DHT dht(DHTPIN, DHTTYPE, 15);
float t_old = 22.00;
String tempTopic;

const char *ssid =  "zzz";      // cannot be longer than 32 characters!
const char *pass =  "zzz";      //

// Update these with values suitable for your network.
IPAddress server(10, 0, 0, 9);

void callback(const MQTT::Publish& pub) {
  // handle message arrived
}

PubSubClient client(server, 1883);

String macToStr(const uint8_t* mac)
{
  String result;
  for (int i = 0; i < 6; ++i) {
    result += String(mac[i], 16);
    if (i < 5)
      result += ':';
  }
  return result;
}

void setup()
{  

  dht.begin();

  // Setup console
  Serial.begin(115200);
  delay(10);

  client.set_callback(callback);

  WiFi.begin(ssid, pass);

  int retries = 0;
  while ((WiFi.status() != WL_CONNECTED) && (retries < 10)) {
    retries++;
    delay(500);
    Serial.print(".");
  }

  delay(500);

  uint8_t mac[6];
  WiFi.macAddress(mac);
  tempTopic += "/";
  tempTopic += macToStr(mac);
  tempTopic += "/";
  tempTopic += "temperature/";
  if (client.connect(MQTT::Connect("arduinoClient")
                 .set_auth("testeruser", "testpass"))) {
  }
}

void loop()
{
    client.loop();  
    delay(2000);

        float t = dht.readTemperature();
        if (isnan(t)){
          Serial.println("Failed to read from DHT sensor!");
        }
        else {
        t_old = t;
        }


        String tempValue = "";
        tempValue += t_old;
        client.publish(tempTopic,tempValue);

      if (client.connected() != 1 || WiFi.status() != WL_CONNECTED)
      {
         ESP.reset(); 
      }

}

[xdanik]

I have similar problem,

when PubSubClient was publishing message and I unplug wifi AP from power, it caused a garbage line in serial monitor and ESP restart itself...

Is there any way to protect itself from reboots?

I tried something like this, but it did not help...

if(WiFi.status() == WL_CONNECTED){
client.publish(topic, msg);
}

[kdschlosser]

i guess there are alot of people with this problem, I had already launched a report about it in april. didn't get a response until today. stated wl_connected only checks to see if you have an IP address that is dynamically assigned, didn't explain anything further. my esp keeps on boot cycling until an IP address is given either static or dynamic don't matter. but is non functional until it has one, doesn't make this piece a viable micro controller because of this problem. Oh and one other thing, take that 20 dollar wal wart (ac to dc adapter usually has the switch on the side to change voltage) and throw it the hell away, 99% of those things are garbage, put them under load and the voltage drops a lot. and if you really insist on using one, put a big cap on it, i needed 2 X 1000uf to smooth out the bounce, lot of them have AC bounce really bad. measure it with nothing connected and everything is fine. junk, for purposes of benching and uploading, a computer PSU has 12V 5V and... 3.3V. 15 to 20 bucks, and what is really nice if ya short something (been up to long???) the PSU drops right out. if you need instruction on how to fire one up without being in a computer msg me, stay away from box brand PSU's HP DELL......sometimes they use non standard pinning on the connector (the connector will actually be the ATX 20+4, wires in different locations tho))

[Opiron]

Hi,

Has somebody found a solution for this?

Regards,

[danoveb]

I think the best workaround until now is to detect WiFi.Status != WL_CONNECTED, and do a short deepsleep so it reboot hardwise. Easy on a Wemos, but not so easy on a SonOff when the XPD_DCDC pin isn't connected to something.

[kdschlosser]

why can't the ESP just run instead of rebooting... because it can still check pin states or whatever else and store the data. but attempt a reconnect every so often. this is a micro controller.. it does many things... it shouldn't be hinged on having an IP address. what if the sole purpose to it was for scanning of AP and signal strengths and data logging the information?? it couldn't. And having an IP address or not does not mean it is not connected to wifi. it just means that it couldn't communicate with a DHCP server. which at that time you could have it connect to a different AP and then perform tasks to notify of a missing DHCP or whatever. but because of how not having an IP means it has no wifi connection and causes a reboot.. you can't achieve this.

I know this is not a limitation of the ESP because micropython works in this manner. this is a limitation of this IDE

[igrr]

@kdschlosser Can you share a sketch which causes ESP to boot loop if fails to get an IP address? Thanks.