因为刚好做作业需要用到双机通信，顺便学习一下，我在网上找了很多方法，试过用蓝牙通信，但是只能实现发送字符串（个人能力只能到这步，等后面有时间再深入研究蓝牙通信）最后实现方式是 AsyncWebServer和HTTPClient实现双机通信。

​ 这里我把ESP32-C3接温湿度传感器、空气报警器的当做服务端，ESP32-C3接OLED显示屏的当做客户端，一个发送数据，一个接受数据。

一、服务端

1、环境配置

需要下载ESPAsyncWebServer库，大家可以去官网下载，也可以用我存放在百度网盘的，一样的资源。下载完以后还是跟之前一样，添加下载库

链接：https://pan.baidu.com/s/1Yr8efIupvVDV9nMvxpvd2Q
提取码：xi0x

2、代码撰写

2.1 调用头文件

#include "WiFi.h"
#include "FS.h"
#include "ESPAsyncWebServer.h"
#include "DHT.h"
#include <Wire.h>

2.2 定义引脚接口、服务器端口

#define DHTPIN 7     //DHT数据口
#define DHTTYPE DHT11   // DHT 11
DHT dht(DHTPIN, DHTTYPE);
const int airtwo =6;   //空气警报器模拟口// Create AsyncWebServer object on port 80
AsyncWebServer server(80);

2.3读取数据

这里写的函数是为了先读取数据，方便数据封装，又因为温湿度的数据函数是库封装好的，那要是我们是要其他传感器数据呢？这里我写了一个空气警报器的，可以借鉴一下。

//温度
String readTemp() {return String(dht.readTemperature());
}//湿度
String readHumi() {return String(dht.readHumidity());
}
//空气
String readAir() {return String(Air());
}String Air(){int newStat1 = digitalRead(airtwo);if(newStat1==HIGH){Serial.println("超过气体阈值\n");String a ="1";return a;}else{String a ="0";return a; }
}

2.4 发送数据

关于“/temperature”这个可根据你自己来定义，这里是搞了三个页面，对应不同的数据。

  server.on("/temperature", HTTP_GET, [](AsyncWebServerRequest *request){request->send_P(200, "text/plain", readTemp().c_str());});server.on("/humidity", HTTP_GET, [](AsyncWebServerRequest *request){request->send_P(200, "text/plain", readHumi().c_str());});server.on("/Air", HTTP_GET, [](AsyncWebServerRequest *request){request->send_P(200, "text/plain", readAir().c_str());});

2.5获取服务端ip地址，我们可以通过串口助手查看或者是打开电脑的移动认定查看

  Serial.print("IP Address:");Serial.println(WiFi.localIP());

3、遇见的问题

在烧录代码的时候，报出了库的问题，说是IPAddress的问题,用ESP32开发板是没问题的，但是用ESP32-C3开发板就报错。一开始我也是在网上找了很久，可是还是没找到相关解决办法，后面根据报错地址，一个一个找，在找到报错的那个点，我把0U删除了，就可以用了。

4、服务端完整代码

// Import required libraries
#include "WiFi.h"
#include "FS.h"
#include "ESPAsyncWebServer.h"
#include "DHT.h"
#include <Wire.h>#define DHTPIN 7  
#define DHTTYPE DHT11   // DHT 11
DHT dht(DHTPIN, DHTTYPE);const char* ssid = "3671";
const char* password = "05210835";
const int airtwo =6;// Create AsyncWebServer object on port 80
AsyncWebServer server(80);String readTemp() {return String(dht.readTemperature());
}String readHumi() {return String(dht.readHumidity());
}
String readAir() {return String(Air());
}
String Air(){int newStat1 = digitalRead(airtwo);if(newStat1==HIGH){Serial.println("超过气体阈值\n");String a ="1";return a;}else{String a ="0";return a;}
}
void setup(){pinMode(airtwo,INPUT);  //空气报警器  是输入// Serial port for debugging purposesSerial.begin(115200);dht.begin();WiFi.begin(ssid, password);while (WiFi.status() != WL_CONNECTED) {delay(500);Serial.print("正在连接中----\n");       }Serial.print("WIFI已连接\n");Serial.print("IP Address:");Serial.println(WiFi.localIP());server.on("/temperature", HTTP_GET, [](AsyncWebServerRequest *request){request->send_P(200, "text/plain", readTemp().c_str());});server.on("/humidity", HTTP_GET, [](AsyncWebServerRequest *request){request->send_P(200, "text/plain", readHumi().c_str());});server.on("/Air", HTTP_GET, [](AsyncWebServerRequest *request){request->send_P(200, "text/plain", readAir().c_str());});// Start serverserver.begin();
}void setupWifi(){WiFi.begin(ssid, password);while (WiFi.status() != WL_CONNECTED) {delay(500);Serial.print("正在连接中----\n");}Serial.print("WIFI已连接\n");Serial.print(WiFi.localIP());
}
void loop(){
float h = dht.readHumidity(); 
float t = dht.readTemperature(); 
float f = dht.readTemperature(true);
String a =Air();
int newStat1 = digitalRead(airtwo);if(newStat1==HIGH){Serial.println("超过气体阈值\n");}else{  }if (isnan(h) || isnan(t) || isnan(f)) {Serial.println(F("Failed to read from DHT sensor!\n"));return;}//可以让我们通过串口查看数据Serial.print(F("Air: "));   Serial.print(a);Serial.print(F("  Humidity: "));        Serial.print(h);Serial.print(F("%  Temperature: "));Serial.print(t);Serial.print(F("*C  \n "));if (!WiFi.isConnected()) //先看WIFI是否还在连接{setupWifi();}
}

二、客户端

​ 上一篇博客已经讲了OLED的使用，所以这里就一笔带过。讲客户端怎么获取服务端的数据。

1、调用头文件

#include <WiFi.h>
#include <HTTPClient.h>
/* 使用0.96寸的OLED屏幕需要使用包含这个头文件 */
#include "SSD1306Wire.h"

2、服务器的ip地址

对应服务端三个页面存放的数据

//服务端的ip地址
const char* serverNameTemp = "http://192.168.137.82/temperature";  
const char* serverNameHumi = "http://192.168.137.82/humidity";
const char* serverNameAir = "http://192.168.137.82/Air";

3、获取http网页函数

String httpGETRequest(const char* serverName) {HTTPClient http;// Your IP address with path or Domain name with URL path http.begin(serverName);// Send HTTP POST requestint httpResponseCode = http.GET();String payload = "--"; if (httpResponseCode>0) {Serial.print("HTTP Response code: ");Serial.println(httpResponseCode);payload = http.getString();}else {Serial.print("Error code: ");Serial.println(httpResponseCode);}// Free resourceshttp.end();return payload;
}

4、获取的数据显示到显示屏上

   String temperature = httpGETRequest(serverNameTemp);String Humidity = httpGETRequest(serverNameHumi);String Airpost  =httpGETRequest(serverNameAir);unsigned long currentMillis = millis();if(Airpost =="0"){oled.drawString(0,40, "Air:warning"); // 数值为0是 显示warning}else{oled.drawString(0,40, "Air:normal"); // 数值为1是 显示normal}/* 1. 显示字母 */oled.setFont(ArialMT_Plain_16);       // 设置字体oled.drawString(0,0, "Temp:" +temperature+"C"); // 将要显示的字母写入缓存oled.drawString(0,20, "Humidity:"+Humidity+"%"); // 将要显示的字母写入缓存oled.display();                       // 将缓存里的文字在屏幕上显示delay(10000);oled.clear(); oled.display();         // 清除屏幕

5、客户端完整代码

#include <WiFi.h>
#include <HTTPClient.h>
/* 使用0.96寸的OLED屏幕需要使用包含这个头文件 */
#include "SSD1306Wire.h"
const char* ssid = "3671";
const char* password = "05210835";
//Your IP address or domain name with URL path
//服务端的ip地址
const char* serverNameTemp = "http://192.168.137.82/temperature";
const char* serverNameHumi = "http://192.168.137.82/humidity";
const char* serverNameAir = "http://192.168.137.82/Air";/* 设置oled屏幕的相关信息 */
const int I2C_ADDR = 0x3c;              // oled屏幕的I2c地址
#define SDA_PIN 5                       // SDA引脚，默认gpio4(D2)
#define SCL_PIN 4                       // SCL引脚，默认gpio5(D1)/* 新建一个oled屏幕对象，需要输入IIC地址，SDA和SCL引脚号 */
SSD1306Wire oled(I2C_ADDR, SDA_PIN, SCL_PIN);unsigned long previousMillis = 0;
const long interval = 5000; void setup() {Serial.begin(115200);WiFi.begin(ssid, password);Serial.println("Connecting");while(WiFi.status() != WL_CONNECTED) { delay(500);Serial.print(".");}Serial.println("");Serial.print("Connected to WiFi network with IP Address: ");Serial.println(WiFi.localIP());/* 2. oled屏幕初始化 */oled.init();oled.flipScreenVertically();          // 设置屏幕翻转oled.setContrast(255);                // 设置屏幕亮度drawRect();                           // 测试屏幕显示oled.clear(); oled.display();         // 清除屏幕
}void drawRect(void) {for (int16_t i=0; i<oled.getHeight()/2; i+=2) {oled.drawRect(i, i, oled.getWidth()-2*i, oled.getHeight()-2*i);oled.display();delay(50);}
}void loop() {String temperature = httpGETRequest(serverNameTemp);String Humidity = httpGETRequest(serverNameHumi);String Airpost  =httpGETRequest(serverNameAir);unsigned long currentMillis = millis();if(Airpost =="0"){oled.drawString(0,40, "Air:warning"); // 将要显示的字母写入缓存}else{oled.drawString(0,40, "Air:normal"); // 将要显示的字母写入缓存}/* 1. 显示字母 */oled.setFont(ArialMT_Plain_16);       // 设置字体oled.drawString(0,0, "Temp:" +temperature+"C"); // 将要显示的字母写入缓存oled.drawString(0,20, "Humidity:"+Humidity+"%"); // 将要显示的字母写入缓存oled.display();                       // 将缓存里的文字在屏幕上显示delay(10000);oled.clear(); oled.display();         // 清除屏幕if(currentMillis - previousMillis >= interval) {// Check WiFi connection statusif(WiFi.status()== WL_CONNECTED ){ Serial.println("Temperature: " + temperature + " *C - Humidity: " + Humidity+ "%" );// save the last HTTP GET RequestpreviousMillis = currentMillis;}else {Serial.println("WiFi Disconnected");}}
}String httpGETRequest(const char* serverName) {HTTPClient http;// Your IP address with path or Domain name with URL path http.begin(serverName);// Send HTTP POST requestint httpResponseCode = http.GET();String payload = "--"; if (httpResponseCode>0) {Serial.print("HTTP Response code: ");Serial.println(httpResponseCode);payload = http.getString();}else {Serial.print("Error code: ");Serial.println(httpResponseCode);}// Free resourceshttp.end();return payload;
}

三、效果展示

写到这里，终于放假回家了，新的一年再继续加油努力吧！！！
凛冬散尽 星河长明 新的一年 万事顺遂