通过ESP8266 NodeMCU建立TCP/UDP Server，可以轻松实现单点/多点Client与MCU的通信， WiFiServer库用于ESP8266的TCP协议通信，WiFiUDP库用于UDP协议通信。 为了不阻塞Loop中的任务，而且Ticker中不建议进行阻塞式IO，则可以用Ticker负责检测新的客户端连接或者新数据包，Loop中进行IO操作，这样更高效。

TCP通信

WiFiServer库用于ESP8266的TCP协议物联网通讯。

1、Loop直接操作

TcpServer.cpp

cpp
#include <Arduino.h>
#include <ESP8266WiFi.h>

#define SERVER_PORT 8080
#define MAX_SRV_CLIENTS 2

WiFiServer server(SERVER_PORT);
WiFiClient serverClients[MAX_SRV_CLIENTS];

#define SSID "TP-LINK"
#define PASSWORD "192.168.1.1"

void setup() {
    Serial.begin(9600);
    WiFi.mode(WIFI_STA);

    WiFi.begin(SSID, PASSWORD);

    while (WiFi.status() != WL_CONNECTED) {
        delay(1000);
        Serial.print(".");
    }
    Serial.println("\nWiFi Connected!");
    server.begin();
    // 关闭小包合并包功能，不会延时发送数据
    server.setNoDelay(true);
    Serial.printf("server start success, %s:%d",
                  WiFi.localIP().toString().c_str(),
                  SERVER_PORT);
}

// 读取数据缓冲区(根据需求调整)
char *readBuffer = new char[128];

void loop() {
    int i = 0;
    // 读取数据大小
    size_t readSize = 0;

    // 判断是否有新的Client请求进来
    if (server.hasClient()) {
        for (i = 0; i < MAX_SRV_CLIENTS; i++) {
            // 释放旧无效或者断开的client
            if (!serverClients[i] || !serverClients[i].connected()) {
                if (!serverClients[i]) {
                    // 停止指定客户端的连接
                    serverClients[i].stop();
                }
                // 分配最新的client
                serverClients[i] = server.available();
                Serial.printf("A new client -> %d\n", i);
                break;
            }
        }
    }

    // 当达到最大连接数，无法释放无效的Client，需要拒绝连接
    if (i == MAX_SRV_CLIENTS) {
        WiFiClient client = server.available();
        client.stop();
        Serial.println("Max Connections, Connection rejected");
    }

    // 检测是否有Client发过来的数据
    for (i = 0; i < MAX_SRV_CLIENTS; i++) {
        if (serverClients[i] && serverClients[i].connected()) {
            // 判断指定客户端是否有可读数据
            if (serverClients[i].available()) {
                readSize = serverClients[i].peekAvailable();
                serverClients[i].read(readBuffer, readSize);
                Serial.write(readBuffer, readSize);
                // 数据回传给Client
                serverClients[i].write(readBuffer, readSize);
            }
        }
    }
}

2、Ticker定时操作

TcpServer.cpp

cpp
#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <Ticker.h>

#define SERVER_PORT 8080
#define MAX_SRV_CLIENTS 2

WiFiServer server(SERVER_PORT);
WiFiClient serverClients[MAX_SRV_CLIENTS];

#define SSID "TP-LINK"
#define PASSWORD "192.168.1.1"

Ticker handTcpTicker;

// 读取数据缓冲区(根据需求调整)
char *readBuffer = new char[128];

void handTcpMessage(){
    int i = 0;
    // 读取数据大小
    size_t readSize = 0;

    // 判断是否有新的Client请求进来
    if (server.hasClient()) {
        for (i = 0; i < MAX_SRV_CLIENTS; i++) {
            // 释放旧无效或者断开的client
            if (!serverClients[i] || !serverClients[i].connected()) {
                if (!serverClients[i]) {
                    // 停止指定客户端的连接
                    serverClients[i].stop();
                }
                // 分配最新的client
                serverClients[i] = server.available();
                Serial.printf("A new client -> %d\n", i);
                break;
            }
        }
    }

    // 当达到最大连接数，无法释放无效的Client，需要拒绝连接
    if (i == MAX_SRV_CLIENTS) {
        WiFiClient client = server.available();
        client.stop();
        Serial.println("Max Connections, Connection rejected");
    }

    // 检测是否有Client发过来的数据
    for (i = 0; i < MAX_SRV_CLIENTS; i++) {
        if (serverClients[i] && serverClients[i].connected()) {
            // 判断指定客户端是否有可读数据
            if (serverClients[i].available()) {
                readSize = serverClients[i].peekAvailable();
                serverClients[i].read(readBuffer, readSize);
                Serial.write(readBuffer, readSize);
                // 数据回传给Client
                serverClients[i].write(readBuffer, readSize);
            }
        }
    }
}

void setup() {
    Serial.begin(9600);
    WiFi.mode(WIFI_STA);

    WiFi.begin(SSID, PASSWORD);

    while (WiFi.status() != WL_CONNECTED) {
        delay(1000);
        Serial.print(".");
    }
    Serial.println("\nWiFi Connected!");
    server.begin();
    //关闭小包合并包功能，不会延时发送数据
    server.setNoDelay(true);
    Serial.printf("server start success, %s:%d\n",
                  WiFi.localIP().toString().c_str(),
                  SERVER_PORT);


    handTcpTicker.attach_ms(5, handTcpMessage);
}

void loop() {

}

3、Ticker标志位优化

也就是说，不建议在Ticker回调函数里执行阻塞IO的操作（比如网络、序列化、文件读写）。应该在Ticker回调函数中设置一个标志位，并在循环函数中检查该标志，符合条件的情况的下进行IO操作即可。

cpp
#include <ESP8266WiFi.h>
#include <Ticker.h>

#define SERVER_PORT 8080
#define MAX_SRV_CLIENTS 2

WiFiServer server(SERVER_PORT);
WiFiClient serverClients[MAX_SRV_CLIENTS];

#define SSID "TP-LINK"
#define PASSWORD "192.168.1.1"

Ticker handTcpTicker;
// 读取数据缓冲区(根据需求调整)
char *readBuffer = new char[1024];
// 读取数据的ClientId
int availableClientId = -1;
// 是否需要激活IO
bool activateMsgHand = false;

void handTcpMessage(){
    int i = 0;
    // 读取数据大小
    size_t readSize = 0;

    // 判断是否有新的Client请求进来
    if (server.hasClient()) {
        for (i = 0; i < MAX_SRV_CLIENTS; i++) {
            // 释放旧无效或者断开的client
            if (!serverClients[i] || !serverClients[i].connected()) {
                if (!serverClients[i]) {
                    // 停止指定客户端的连接
                    serverClients[i].stop();
                }
                // 分配最新的client
                serverClients[i] = server.available();
                Serial.printf("A new client -> %d\n", i);
                break;
            }
        }
    }

    // 当达到最大连接数，无法释放无效的Client，需要拒绝连接
    if (i == MAX_SRV_CLIENTS) {
        WiFiClient client = server.available();
        client.stop();
        Serial.println("Max Connections, Connection rejected");
    }

    // 检测是否有Client发过来的数据
    for (i = 0; i < MAX_SRV_CLIENTS; i++) {
        if (serverClients[i] && serverClients[i].connected()) {
            // 判断指定客户端是否有可读数据
            if (serverClients[i].available()) {
                activateMsgHand = true;
                availableClientId = i;
            }
        }
    }
}

void setup() {
    Serial.begin(9600);
    WiFi.mode(WIFI_STA);

    WiFi.begin(SSID, PASSWORD);

    while (WiFi.status() != WL_CONNECTED) {
        delay(1000);
        Serial.print(".");
    }
    Serial.println("\nWiFi Connected!");
    server.begin();
    //关闭小包合并包功能，不会延时发送数据
    server.setNoDelay(true);
    Serial.printf("server start success, %s:%d\n",
                  WiFi.localIP().toString().c_str(),
                  SERVER_PORT);
    handTcpTicker.attach_ms(10, handTcpMessage);
}

void loop() {
    if(activateMsgHand){
        // 读取Client数据
        size_t size = serverClients[availableClientId].peekAvailable();
        serverClients[availableClientId].read(readBuffer, size);
        // 串口打印数据
        Serial.write(readBuffer, size);

        // 向客户端回发数据
        serverClients[availableClientId].write(readBuffer, size);

        // 重置标志位
        activateMsgHand = false;
    }
}

UDP通信

WiFiUDP库用于ESP8266开发板的物联网通讯控制以及UDP协议数据包处理。

1、Ticker标志位优化

UdpServer.cpp

cpp
#include <ESP8266WiFi.h>
#include <Ticker.h>
#include <WiFiUdp.h>

// 本地UDP端口
#define LOCAL_UDP_PORT 8080
#define SSID "TP-LINK"
#define PASSWORD "192.168.1.1"

WiFiUDP Udp;
Ticker handUdpTicker;

// 读取数据缓冲区(根据需求调整)
char *readBuffer = new char[1024];
// 是否需要激活IO
bool activateMsgHand = false;
// UDP数据包大小
int packetSize = 0;

void handUdpMessage(){
    // 获得解析包
    packetSize = Udp.parsePacket();
    if(packetSize) {
        activateMsgHand = true;
    }
}

void setup() {
    Serial.begin(9600);
    WiFi.mode(WIFI_STA);

    WiFi.begin(SSID, PASSWORD);

    while (WiFi.status() != WL_CONNECTED) {
        delay(1000);
        Serial.print(".");
    }
    Serial.println("\nWiFi Connected!");

    if(Udp.begin(LOCAL_UDP_PORT)){
        Serial.printf("Start listen IP:%s, UDP port:%d\n",
                      WiFi.localIP().toString().c_str(),
                      LOCAL_UDP_PORT);
    }

    handUdpTicker.attach_ms(10, handUdpMessage);
}

void loop() {
    if(activateMsgHand){
        // 收到Udp数据包
        Serial.printf("form %s:%d -> package size = %d\n",
                      Udp.remoteIP().toString().c_str(),
                      Udp.remotePort(), packetSize);

        // 读取Udp数据包并存放在incomingPacket
        int len = Udp.read(readBuffer, 1024);//返回数据包字节数
        if (len > 0){
            // 添加字符串结束标识符
            readBuffer[len] = '\0';
        }

        // 向串口打印信息
        Serial.printf("content is %s\n", readBuffer);

        // 向客户端回发消息
        Udp.beginPacket(Udp.remoteIP(), Udp.remotePort());
        Udp.write(readBuffer);
        Udp.endPacket();

        // 重置标志位
        activateMsgHand = false;
    }
}