8266控制小车的代码

以下是一个使用ESP8266控制小车的示例代码，可以参考：

#include <WiFi.h>
#include <PubSubClient.h>

// WiFi网络名称和密码
const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";

// MQTT服务器的IP地址、端口、用户名和密码
const char* mqtt_server = "your_MQTT_SERVER_IP";
const int mqtt_port = 1883;
const char* mqtt_user = "your_MQTT_USERNAME";
const char* mqtt_password = "your_MQTT_PASSWORD";

// MQTT客户端和WiFi客户端
WiFiClient espClient;
PubSubClient client(espClient);

// 小车控制引脚
const int left_forward = 13;
const int left_backward = 12;
const int right_forward = 14;
const int right_backward = 27;

void setup() {
  // 设置小车控制引脚为输出模式
  pinMode(left_forward, OUTPUT);
  pinMode(left_backward, OUTPUT);
  pinMode(right_forward, OUTPUT);
  pinMode(right_backward, OUTPUT);

  // 连接WiFi网络
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
  }

  // 连接到MQTT服务器
  client.setServer(mqtt_server, mqtt_port);
  while (!client.connected()) {
    if (client.connect("ESP8266Client", mqtt_user, mqtt_password )) {
      Serial.println("Connected to MQTT server");
      client.subscribe("car/control");
    } else {
      Serial.print("Failed to connect to MQTT server, rc=");
      Serial.print(client.state());
      delay(5000);
    }
  }

  // 初始化串口
  Serial.begin(115200);
}

void loop() {
  // 检查WiFi连接状态
  if (WiFi.status() != WL_CONNECTED) {
    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
      delay(1000);
    }
  }

  // 检查MQTT连接状态
  if (!client.connected()) {
    if (client.connect("ESP8266Client", mqtt_user, mqtt_password )) {
      Serial.println("Connected to MQTT server");
      client.subscribe("car/control");
    }
  }

  // 处理MQTT消息
  client.loop();
}

// 处理MQTT收到的消息
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();

  // 根据收到的消息控制小车
  if (strcmp((char*)topic, "car/control") == 0) {
    if (strcmp((char*)payload, "forward") == 0) {
      digitalWrite(left_forward, HIGH);
      digitalWrite(left_backward, LOW);
      digitalWrite(right_forward, HIGH);
      digitalWrite(right_backward, LOW);
    } else if (strcmp((char*)payload, "backward") == 0) {
      digitalWrite(left_forward, LOW);
      digitalWrite(left_backward, HIGH);
      digitalWrite(right_forward, LOW);
      digitalWrite(right_backward, HIGH);
    } else if (strcmp((char*)payload, "left") == 0) {
      digitalWrite(left_forward, LOW);
      digitalWrite(left_backward, HIGH);
      digitalWrite(right_forward, HIGH);
      digitalWrite(right_backward, LOW);
    } else if (strcmp((char*)payload, "right") == 0) {
      digitalWrite(left_forward, HIGH);
      digitalWrite(left_backward, LOW);
      digitalWrite(right_forward, LOW);
      digitalWrite(right_backward, HIGH);
    } else if (strcmp((char*)payload, "stop") == 0) {
      digitalWrite(left_forward, LOW);
      digitalWrite(left_backward, LOW);
      digitalWrite(right_forward, LOW);
      digitalWrite(right_backward, LOW);
    }
  }
}

这个示例代码通过连接到MQTT服务器，订阅主题 "car/control"，然后根据收到的消息控制小车的运动。可以通过向 "car/control" 发布消息，控制小车向前、向后、向左、向右或停止。