WiFi.scanComplete() always return -2 on ESP32

[Rezaasghariir]

In esp32-wroom-32 when i want scan WiFi station WiFi.scanComplete() always return -2
my code is :
/*

• This sketch demonstrates how to scan WiFi networks.
• The API is almost the same as with the WiFi Shield library,
• the most obvious difference being the different file you need to include:
  */
  #include "WiFi.h"

void setup()
{
Serial.begin(115200);

// Set WiFi to station mode and disconnect from an AP if it was previously connected
WiFi.mode(WIFI_STA);
WiFi.disconnect();
delay(100);

Serial.println("Setup done");

}

void loop()
{
Serial.println("scan start");

// WiFi.scanNetworks will return the number of networks found
int n = WiFi.scanComplete();
Serial.println("scan done");
if (n == 0) {
    Serial.println("no networks found");
} else {
    Serial.print(n);
}
Serial.println("");

// Wait a bit before scanning again
delay(5000);

}
I thinks its a bug

[DmitryBorisenko33]

Same situation.

boolean RouterFind(String ssid) {

  int n = WiFi.scanComplete();
  Serial.print("status=");
  Serial.println(n);
  if (n == -2) {                       //Сканирование не было запущено, запускаем
    //WiFi.disconnect();
    //WiFi.begin();
    WiFi.scanNetworks (true, false);   //async, show_hidden
    Serial.println("->start scanning");
    return false;
  }
  if (n == -1) {                       //Сканирование все еще выполняется
    Serial.println("->scanning in progress");
    return false;

  }
  if (n > 0) {
    for (int i = 0; i <= n; i++) {
      if (WiFi.SSID(i) == ssid) {
        Serial.println("router found");
        WiFi.scanDelete();
        return true;
      } else {
        Serial.print(i);
        Serial.print(")");
        Serial.print(ssid);
        Serial.print("<=>");
        Serial.println(WiFi.SSID(i));
      }
    }
    WiFi.scanDelete();
    Serial.println("->scanning deleted");
    return false;
  }
}

I see that WiFi.scanComplete() return -2

this procedure working long time properly on esp8266

[atanisoft]

WiFi.scanComplete() will return WIFI_SCAN_FAILED (-2) IF you don't call WiFi.scanNetworks() (with or without arguments). The code which @Rezaasghariir provided doesn't call WiFi.scanNetworks() so it is rightfully returning WIFI_SCAN_FAILED since no scan has been initiated.

[DmitryBorisenko33]

ok. i tested one more time. My problem is when i call WiFi.scanNetworks (true, false); first time everything ok. After i make WiFi.scanDelete();. Than (after 30 sec) i again call WiFi.scanNetworks (true, false); and my code stop working. Probably code not going out from WiFi.scanNetworks function.

[DmitryBorisenko33]

I try many times. When i call WiFi.scanNetworks (true, false) second time, and previous scanning was already completed, all freeze.

And i know exactly - previous scanning completed fully. I have this signal about it:

[D][WiFiGeneric.cpp:337] _eventCallback(): Event: 1 - SCAN_DONE

My full code:

bool StartAPMode() {

  Serial.println("WiFi up AP");
  IPAddress apIP(192, 168, 4, 1);
  IPAddress staticGateway(192, 168, 4, 1);
  IPAddress staticSubnet(255, 255, 255, 0);
  // Отключаем WIFI
  WiFi.disconnect();
  // Меняем режим на режим точки доступа
  WiFi.mode(WIFI_AP);
  // Задаем настройки сети
  WiFi.softAPConfig(apIP, staticGateway, staticSubnet);
  //Включаем DNS
  //dnsServer.start(53, "*", apIP);
  // Включаем WIFI в режиме точки доступа с именем и паролем
  // хронящихся в переменных _ssidAP _passwordAP
  String _ssidAP = jsonRead(configSetup, "ssidAP");
  String _passwordAP = jsonRead(configSetup, "passwordAP");
  WiFi.softAP(_ssidAP.c_str(), _passwordAP.c_str());
  jsonWrite(configJson, "ip", apIP.toString());

  
    researching_wifi.attach(30, Async_researching_wifi);

  return true;
}

void Async_researching_wifi() {
  Serial.println("->try find router");
  if (RouterFind(jsonRead(configSetup, "ssid"))) {
    researching_wifi.detach();
    WIFI_init();
    //MQTT_init();
  }
}

boolean RouterFind(String ssid) {

  int n = WiFi.scanComplete();
  
  Serial.print("status=");
  Serial.println(n);
  
  if (n == -2) {                       //Сканирование не было запущено, запускаем  
    Serial.println("->enter to scanning function");
    WiFi.scanNetworks (true, false);   //async, show_hidden
    Serial.println("->out of scanning function");
    return false;
    
  }
  if (n == -1) {                       //Сканирование все еще выполняется
    Serial.println("->scanning in progress");
    return false;

  }
  if (n > 0) {                         //Найдено несколько сетей
    for (int i = 0; i <= n; i++) {
      if (WiFi.SSID(i) == ssid) {
        Serial.println("router found");
        WiFi.scanDelete();
        return true;
      } else {
        Serial.print(i);
        Serial.print(")");
        Serial.print(ssid);
        Serial.print("<=>");
        Serial.println(WiFi.SSID(i));
      }
    }
    WiFi.scanDelete();
    Serial.println("->scanning deleted");
    return false;
  }
}

My debug information:

->try find router
status=-2
->enter to scanning function
->out of scanning function
[D][WiFiGeneric.cpp:337] _eventCallback(): Event: 2 - STA_START
[D][WiFiGeneric.cpp:337] _eventCallback(): Event: 1 - SCAN_DONE
->try find router
status=11
0)test<=>RT-WiFi_A78F
1)test<=>MGTS_GPON_1002
2)test<=>MGTS_GPON_7858
3)test<=>MGTS_GPON_7630
4)test<=>AKADO-1DB0
5)test<=>alexsandr
6)test<=>MGTS_GPON_70E1
7)test<=>112
8)test<=>Beeline_2G_F12137
9)test<=>MGTS_GPON_E6C7
10)test<=>kv108
11)test<=>
->scanning deleted
->try find router
status=-2
->enter to scanning function

at this line ->enter to scanning function all freeze.

[btreecat]

I can confirm that additional calls to
WiFi.scanNetworks()
Return -2 even with 120 seconds between them (plenty of time to let the scan finish).

Currently this means I can scan once in the setup() method because if I scan again in the loop it will fail. Seems like a bug as you should always be able to rescan.

[stale]

[STALE_SET] This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

[btreecat]

This is still an open issue.

…

-- Stephen Tanner Part 107 Certified Drone Pilot Web, Research, and Cloud Application Developer Virginia Tech Transportation Institute https://TannAir.com https://StephenTanner.com

On Fri, Jan 31, 2020, 14:22 stale[bot] ***@***.***> wrote: [STALE_SET] This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3302?email_source=notifications&email_token=AAB3OHGVB362QX6RQABKVADRAR27NA5CNFSM4I3XYHLKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEKPW7HA#issuecomment-580874140>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAB3OHC7PH4WLSZQAIXE6B3RAR27NANCNFSM4I3XYHLA> .

[stale]

[STALE_CLR] This issue has been removed from the stale queue. Please ensure activity to keep it openin the future.

[stale]

[STALE_SET] This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

[btreecat]

Still a problem. Is any one else able to reproduce?

…

-- Stephen Tanner Part 107 Certified Drone Pilot Web, Research, and Cloud Application Developer Virginia Tech Transportation Institute https://TannAir.com https://StephenTanner.com

On Tue, Mar 31, 2020, 16:03 stale[bot] ***@***.***> wrote: [STALE_SET] This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3302 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAB3OHEMI5F2EQOQ7FLGMN3RKJD77ANCNFSM4I3XYHLA> .

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[STALE_CLR] This issue has been removed from the stale queue. Please ensure activity to keep it openin the future.