ESP32 WebServer输入错误WiFi触发看门狗复位问题求助
ESP32 AP模式WiFi配置触发看门狗复位问题排查与解决
问题现象
使用ESP32开发板实现AP模式引导用户输入WiFi信息,配置完成后切换到STA模式启动WebServer。输入正确WiFi信息时设备可正常连接运行;但输入错误信息时,连接失败分支输出debug4后5秒触发看门狗复位,设备重启。
串口日志
19:18:44:830 -> Trying to connect... 19:18:45:330 -> Trying to connect... 19:18:45:332 -> debug 19:18:45:333 -> debug4 19:18:50:330 -> E (20302) task_wdt: Task watchdog got triggered. The following tasks did not reset the watchdog in time: 19:18:50:339 -> E (20302) task_wdt: - async_tcp (CPU 0/1) 19:18:50:343 -> E (20302) task_wdt: Tasks currently running: 19:18:50:347 -> E (20302) task_wdt: CPU 0: IDLE 19:18:50:350 -> E (20302) task_wdt: CPU 1: loopTask 19:18:50:353 -> E (20302) task_wdt: Aborting. 19:18:50:356 -> 19:18:50:356 -> abort() was called at PC 0x400e8e95 on core 0 19:18:50:360 -> 19:18:50:360 -> 19:18:50:361 -> Backtrace: 0x4008389d:0x3ffbec3c |<-CORRUPTED 19:18:50:365 -> 19:18:50:365 -> 19:18:50:365 -> 19:18:50:365 -> 19:18:50:365 -> ELF file SHA256: 12c7e27a4eeae93f 19:18:50:368 -> 19:18:50:846 -> Rebooting... 19:18:50:848 -> ets Jul 29 2019 12:21:46
现有代码
void startAPMode() { if (apmode == true) { WiFi.mode(WIFI_AP_STA); WiFi.softAP(apSSID, apPassword); apServer.on("/", HTTP_GET, [](AsyncWebServerRequest* request) { request->send(200, "text/html", ap_mode_html); }); apServer.on("/setup", HTTP_GET, [](AsyncWebServerRequest* request) { if (request->hasParam("ssid") && request->hasParam("password")) { String ssid = request->getParam("ssid")->value(); String password = request->getParam("password")->value(); WiFi.begin(ssid.c_str(), password.c_str()); unsigned long startTime = millis(); bool connectionSuccessful = false; while (millis() - startTime < 10000) { esp_task_wdt_reset(); // Reset Watchdog Timer if (WiFi.status() == WL_CONNECTED) { connectionSuccessful = true; break; } delay(500); Serial.println("Versuche zu verbinden..."); } //esp_task_wdt_reset(); Serial.println("debug"); if (connectionSuccessful) { IPAddress wifiIP = WiFi.localIP(); String response = R"html( <!DOCTYPE html> <html> <head> <title>Verbindung Erfolgreich</title> <style> html, body { font-family: Arial, sans-serif; margin: 0; padding: 0; display: flex; justify-content: center; align-items: center; flex-direction: column; } .container { padding: 20px; border: 1px solid #ddd; border-radius: 5px; background-color: #fff; box-shadow: 0 2px 4px rgba(0,0,0,0.1); max-width: 90%; } .ip-address { font-weight: bold; margin-top: 20px; padding: 10px; background-color: #e9ecef; border-radius: 5px; } </style> </head> <body> <div class='container'> Verbindung erfolgreich! Bitte diese IP Adresse aufschreiben oder merken. Über diese IP Adresse kann nun immer die Fenstersteuerung aufgerufen werden! <div class='ip-address'>Die IP Adresse für die Webseite ist: )html" + wifiIP.toString() + R"html(</div> </div> </body> </html> )html"; request->send(200, "text/html", response); Serial.println("debug2"); setupWiFiAndWebServer(); Serial.println("debug3"); } else { esp_task_wdt_reset(); Serial.println("debug4"); //WiFi.disconnect(); // Optional: trennt die Verbindung, wenn nicht erfolgreich String response = "Connection failed! <a href='/'>Try again</a>"; request->send(200, "text/html", response); Serial.println("debug5"); startAPMode(); } } else { esp_task_wdt_reset(); request->send(200, "text/html", "Missing data! <a href='/'>Back</a>"); startAPMode(); } }); apServer.begin(); Serial.println("AP-Modus Webserver gestartet auf " + WiFi.softAPIP().toString()); } }
问题根源
- 阻塞AsyncWebServer回调线程:在
/setup的GET请求回调中,使用while循环等待WiFi连接,最长阻塞10秒。AsyncWebServer依赖async_tcp任务处理请求,长时间阻塞会导致该任务无法喂狗,触发看门狗超时。 - 递归调用
startAPMode():连接失败或参数缺失时递归调用startAPMode(),会重复初始化AP和WebServer,导致任务调度混乱,同时可能造成栈溢出,进一步加剧看门狗触发风险。 - WiFi状态未清理:连接失败后未彻底断开WiFi,残留的连接状态可能干扰后续操作,延长任务阻塞时间。
解决方案
1. 改用非阻塞式WiFi连接(状态机管理)
将WiFi连接逻辑从请求回调中移出,放到loop()函数里用状态机管理,避免阻塞async_tcp任务:
// 定义全局状态变量 enum DeviceState { STATE_AP_WAIT_INPUT, STATE_WIFI_CONNECTING, STATE_WIFI_CONNECTED, STATE_WIFI_FAILED }; DeviceState currentState = STATE_AP_WAIT_INPUT; String targetSSID, targetPassword; unsigned long connectStartTime; bool apmode = false; AsyncWebServer apServer(80); const char* apSSID = "ESP32-Setup"; const char* apPassword = "12345678"; const char* ap_mode_html = "<html><body><form action='/setup' method='GET'>SSID: <input type='text' name='ssid'><br>Password: <input type='password' name='password'><br><input type='submit' value='Connect'></form></body></html>"; void setup() { Serial.begin(115200); startAPMode(); } void loop() { switch(currentState) { case STATE_WIFI_CONNECTING: if(millis() - connectStartTime > 10000) { // 连接超时,标记失败 currentState = STATE_WIFI_FAILED; WiFi.disconnect(true); // 彻底断开WiFi startAPMode(); // 回到AP模式 } else if(WiFi.status() == WL_CONNECTED) { currentState = STATE_WIFI_CONNECTED; setupWiFiAndWebServer(); } break; case STATE_WIFI_FAILED: // 无需额外操作,已回到AP模式等待用户重试 break; default: break; } } void startAPMode() { apmode = true; WiFi.mode(WIFI_AP_STA); WiFi.softAP(apSSID, apPassword); apServer.on("/", HTTP_GET, [](AsyncWebServerRequest* request) { request->send(200, "text/html", ap_mode_html); }); apServer.on("/setup", HTTP_GET, [](AsyncWebServerRequest* request) { if (request->hasParam("ssid") && request->hasParam("password")) { targetSSID = request->getParam("ssid")->value(); targetPassword = request->getParam("password")->value(); // 启动WiFi连接,切换状态 currentState = STATE_WIFI_CONNECTING; connectStartTime = millis(); WiFi.begin(targetSSID.c_str(), targetPassword.c_str()); // 立即返回响应,不等待连接结果 request->send(200, "text/html", "Connecting to WiFi... Please refresh later or check the device status."); } else { request->send(200, "text/html", "Missing data! <a href='/'>Back</a>"); } }); apServer.begin(); Serial.println("AP-Modus Webserver gestartet auf " + WiFi.softAPIP().toString()); } // 示例WebServer初始化函数 void setupWiFiAndWebServer() { apmode = false; apServer.end(); // 关闭AP模式的WebServer // 初始化STA模式下的WebServer逻辑 Serial.println("STA WebServer initialized"); }
2. 移除递归调用,避免重复初始化
连接失败时直接切换状态回AP模式,无需重复调用startAPMode()。如果需要重置AP配置,可单独写一个重置函数,而非递归触发整个流程。
3. 彻底清理WiFi状态
连接失败时调用WiFi.disconnect(true),清除之前的连接信息,确保下次连接不受干扰。
4. 替代手动喂狗的根本方案
手动喂狗只是临时 workaround,正确的做法是不要在异步任务回调中执行阻塞操作。所有耗时操作(如WiFi连接、传感器读取)都应放到独立的FreeRTOS任务或loop()的非阻塞逻辑中,保证async_tcp等系统任务能正常调度,自然不会触发看门狗。
内容的提问来源于stack exchange,提问作者Friedrich Harald
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