【零知ESP32教程】进阶3：创建Web服务器控制伺服电机
介绍：利用ESP32的WIFI模块，创建一个简单的网络服务器来控制伺服电机。可以使用任何具有浏览器功能的设备访问要构建的网络服务器：本地网络上的智能手机，平板电脑，笔记本电脑等。
硬件：
1、零知ESP32
2、伺服电机
接线：
软件：
零知开发工具
代码：
注意：
1、代码导入之后需要根据自己的本地网络在下面的两行代码中填写无线网名称和密码！
//找到下面两行填写WiFi名称和密码
const char* ssid = "";
const char* password = "";2、需要导入伺服电机的库文件，见附件。
#include <WiFi.h>
#include "Servo.h"
Servo myservo;// create servo object to control a servo
// twelve servo objects can be created on most boards
// GPIO the servo is attached to
static const int servoPin = 13;
// Replace with your network credentials
const char* ssid = "";
const char* password = "";
// Set web server port number to 80
WiFiServer server(80);
// Variable to store the HTTP request
String header;
// Decode HTTP GET value
String valueString = String(5);
int pos1 = 0;
int pos2 = 0;
void setup() {
Serial.begin(9600);
delay(1000);
myservo.attach(servoPin);// attaches the servo on the servoPin to the servo object
// Connect to Wi-Fi network with SSID and password
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
// Print local IP address and start web server
Serial.println("");
Serial.println("WiFi connected.");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
server.begin();
}
void loop() {
WiFiClient client = server.available(); // Listen for incoming clients
if (client) { // If a new client connects,
Serial.println("New Client."); // print a message out in the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected()) { // loop while the client's connected
if (client.available()) { // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
header += c;
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println("Connection: close");
client.println();
// Display the HTML web page
client.println("<!DOCTYPE html><html>");
client.println("<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">");
client.println("<link rel=\"icon\" href=\"data:,\">");
// CSS to style the on/off buttons
// Feel free to change the background-color and font-size attributes to fit your preferences
client.println("<style>body { text-align: center; font-family: \"Trebuchet MS\", Arial; margin-left:auto; margin-right:auto;}");
client.println(".slider { width: 300px; }</style>");
client.println("<script src=\"https://code.jquery.com/jquery-3.1.1.min.js\"></script>");
// Web Page
client.println("</head><body><h1>ESP32 with Servo</h1>");
client.println("<p>Position: <span id=\"servoPos\"></span></p>");
client.println("<input type=\"range\" min=\"0\" max=\"180\" class=\"slider\" id=\"servoSlider\" onchange=\"servo(this.value)\" value=\"" + valueString + "\"/>");
client.println("<script>var slider = document.getElementById(\"servoSlider\");");
client.println("var servoP = document.getElementById(\"servoPos\"); servoP.innerHTML = slider.value;");
client.println("slider.oninput = function() { slider.value = this.value; servoP.innerHTML = this.value; }");
client.println("$.ajaxSetup({timeout:1000}); function servo(pos) { ");
client.println("$.get(\"/?value=\" + pos + \"&\"); {Connection: close};}</script>");
client.println("</body></html>");
//GET /?value=180& HTTP/1.1
if (header.indexOf("?value=") >= 0) {
pos1 = header.indexOf('=');
pos2 = header.indexOf('&');
valueString = header.substring(pos1 + 1, pos2);
//Rotate the servo
myservo.write(valueString.toInt());
Serial.println(valueString);
}
// The HTTP response ends with another blank line
client.println();
// Break out of the while loop
break;
} else { // if you got a newline, then clear currentLine
currentLine = "";
}
} else if (c != '\r') {// if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
}
}
// Clear the header variable
header = "";
// Close the connection
client.stop();
Serial.println("Client disconnected.");
Serial.println("");
}
}
导入程序代码，在右侧选择ESP32开发板，然后验证程序，如图：
然后上传程序到开发板，打开串口调试窗口，可以看到WiFi已连接，且服务器创建成功，输出本地服务器地址：
使用手机或者电脑的浏览器连接服务器，就能够控制使用滑块控制伺服电机的转动角度了，如图所示：
不怎么懂web，学习下。
顺便请教下
一、
1 .本帖的https://code.jquery.com/jquery-3.1.1.min.js
2. web控彩灯帖子中：https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css
以及https://cdnjs.cloudflare.com/ajax/libs/jscolor/2.0.4/jscolor.min.js
这些CSS，javascript代码是自己写的还是或怎么来的，做什么用的？
二、另外看css这个名字包含bootstrap，是否是说使用了bootstrap前端框架？
三、请教零知的ESP32（或者我们电工常用的STM32）是否也是可以使用互联网行业流行的前端三大框架Angular Vue React？如何使用？如果可以使用，我相信ESP32的价值将会大增
四、后端框架是否也可以使用某些？
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