哈喽各位小夥伴，不知不覺系列文章已經進行一半了(感覺要解鎖成就了)，不知道各位在看完前幾篇後，對Esp32s、程式寫法有沒有更深的認識，如果沒有的話，可以繼續的看下去，因為後面會有更多應用，可以看到更多不同的程式碼，回歸正題，今天要講解用Esp32s的AP mode控制繼電器(Relay)，那我們就直接介紹元件。
圖片取自：使用者繪製
上面紅圈所圈選的就是本次會使用到的繼電器(Relay)，那繼電器的功能常被拿來當作安全保護或控制的功用，為甚麼說這兩點呢，因為繼電器可以利用較小電流控制較大電流的零件，像是控制燈泡、馬達...等等物品，那這可以解釋利用小電流控制大電流的零件，那沒解釋到如何做到安全保護的功用對吧，因為這講解到繼電器的構造，繼電器內部像是個Y，當繼電器接受到電流時，因繼電器內部有電磁鐵會將內部的簧片拉至常開(NO,Normally Open)，但如果沒接收到電內部簧片就固定於至常閉(NC,Normally Close)，那我們可以針對繼電器的這功能做出，當繼電器接收到電流就跳掉，用這點做一個安全保護的功能。
Esp32s GND -> St01 GND
Esp32s Vcc(5V) -> ST01(G) +
Esp32s 23 or 22 -> ST01(G) io
(io這邊可選擇用Esp32s的23或22腳都可以，因為程式碼寫的是兩個按鈕，但如果選擇22那操作時就只能按22的按鈕，反之23也相同)
#include <WiFi.h>
// Replace with your network credentials
const char* ssidAP = "E32_Relay_AP";
const char* passwordAP = "12345678";
// Set web server port number to 80
WiFiServer server(80);
// Variable to store the HTTP request
String header;
// Auxiliar variables to store the current output state
String output0State = "off";
String output2State = "off";
// Assign output variables to GPIO pins
const int output0 = 23;
const int output2 = 22;
void setup() {
Serial.begin(115200);
// Initialize the output variables as outputs
pinMode(output0, OUTPUT);
pinMode(output2, OUTPUT);
// Set outputs to LOW
digitalWrite(output0, LOW);
digitalWrite(output2, LOW);
// Connect to Wi-Fi network with SSID and password
Serial.print("Setting AP (Access Point)…");
// Remove the password parameter, if you want the AP (Access Point) to be open
WiFi.softAP(ssidAP, passwordAP);
delay(500);
IPAddress IP = WiFi.softAPIP();
Serial.print("AP IP address: ");
Serial.println(IP);
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();
// turns the GPIOs on and off
if (header.indexOf("GET /23/on") >= 0) {
Serial.println("GPIO 23 on");
output0State = "on";
digitalWrite(output0, HIGH);
} else if (header.indexOf("GET /23/off") >= 0) {
Serial.println("GPIO 23 off");
output0State = "off";
digitalWrite(output0, LOW);
} else if (header.indexOf("GET /22/on") >= 0) {
Serial.println("GPIO 22 on");
output2State = "on";
digitalWrite(output2, HIGH);
} else if (header.indexOf("GET /22/off") >= 0) {
Serial.println("GPIO 22 off");
output2State = "off";
digitalWrite(output2, LOW);
}
// 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>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}");
client.println(".button { background-color: #4CAF50; border: none; color: white; padding: 16px 40px;");
client.println("text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}");
client.println(".button2 {background-color: #555555;}</style></head>");
// Web Page Heading
client.println("<body><h1>ESP32 Web Server</h1>");
// Display current state, and ON/OFF buttons for GPIO 23
client.println("<p>GPIO 23 - State " + output0State + "</p>");
// If the output0State is off, it displays the ON button
if (output0State=="off") {
client.println("<p><a href=\"/23/on\"><button class=\"button\">ON</button></a></p>");
} else {
client.println("<p><a href=\"/23/off\"><button class=\"button button2\">OFF</button></a></p>");
}
// Display current state, and ON/OFF buttons for GPIO 22
client.println("<p>GPIO 22 - State " + output2State + "</p>");
// If the output2State is off, it displays the ON button
if (output2State=="off") {
client.println("<p><a href=\"/22/on\"><button class=\"button\">ON</button></a></p>");
} else {
client.println("<p><a href=\"/22/off\"><button class=\"button button2\">OFF</button></a></p>");
}
client.println("</body></html>");
// 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("");
}
}
跟之前操作LED AP那篇相同，一樣是連上WiFi然後在瀏覽器上打192.168.4.1，就可連至Esp32s所開啟得網頁中囉，然後就可以看自己接的腳位是23或22去點擊，就可以控制Relay的開啟予關閉
圖片取自：使用者拍攝
你會發現，你會訝異，怎麼跟LED AP長一樣，哎呀你猜對了，就是一樣的寫法。
好了，今天先到這裡!沒想到吧，LED AP的寫法在這邊也可做運用，那可以做運用的原因是因為繼電器也只有分做開啟(ON)與關閉(OFF)，那LED也是相同的狀況，相信我後面還有一篇也是這樣，那就是STA，但下面一篇就是開始講解loop裡面的程式啦，所以請不要覺得我在划水(雖然真的很像)，那我們就下一篇見啦~
iThome鐵人賽
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