Question

今天我得到了我的NodeMCU，我立即开始编码。我想连接到我的WiFi和我的MQTT服务器。

我使用了PubSub示例。

在串口监视器中，我收到了与WiFi成功连接的消息，但是我得到了IP 172.20.10.6。但是我们有一个192.168 ...网络。

然后，当我尝试访问我的MQTT服务器时，它找不到它。当我尝试给NodeMCU一个静态IP时，它也说成功连接并显示我给它的静态IP，但我仍然无法连接到我的MQTT服务器。

我无法ping通NodeMCU，也无法在我的智能手机应用程序中找到它＆＃34; Fing＆＃34;。

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

const char* ssid = "myssid";
const char* password = "mypw";
const char* mqtt_server = "192.168.42.131";

WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;

void setup() {
  pinMode(BUILTIN_LED, OUTPUT);
  // Initialize the BUILTIN_LED pin as an output
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
  // Switch on the LED if an 1 was received as first character
  if ((char)payload[0] == '1') {
    digitalWrite(BUILTIN_LED, LOW);
    // Turn the LED on (Note that LOW is the voltage level
    // but actually the LED is on; this is because
    // it is active low on the ESP-01)
  } else {
    digitalWrite(BUILTIN_LED, HIGH);
    // Turn the LED off by making the voltage HIGH
  }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP8266Client")) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      //client.publish("outTopic", "hello world");
      // ... and resubscribe
      client.subscribe("mathistest");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}
void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
  long now = millis();
  if (now - lastMsg > 2000) {
    lastMsg = now;
    ++value;
    snprintf (msg, 75, "hello world #%ld", value);
  }
}

Answer 1

您很可能遇到DHCP故障。

172.20.x.x地址是不可路由的IP地址（请参阅：https://www.lifewire.com/what-is-a-private-ip-address-2625970），当地址分配失败时，DHCP代码（可能）使用该地址。

退回，DHCP很可能会失败，因为您无法使用正确的SSID和密码连接到Wifi网络。

NodeMCU获取奇怪的IP地址

1 个答案: