ESP32/arduino:LED調光_明るさをテキストで設定

目的:
ESP32基板のLED(IO2) を PWM で調光し、明るさをテキスト(数値)設定する。

方法:
form の <input>でテキストボックスを使用して数値を入力/送信する。
ESP32で 文字列を取得して 数値(0～255) に変換し、 SigmaDelta の duty に与える。

例:

 

  値(0～255)  を テキストボックスに 入力。
  ON ボタンを押す度に 少しづつ明るく なり、OFF ボタンで消灯。
  LED調光(PWM) からの主な変更箇所をハイライト。

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/*  *    WiFi LED ON/OFF TEST  *     PWM Control  *     Duty Input  */    #include <WiFi.h>   const char* ssid = "hogehoge"; const char* password = "hogehogepaswd";   IPAddress ip(192, 168, 1, 32);           // for fixed IP Address IPAddress gateway(192,168, 1, 1);        // IPAddress subnet(255, 255, 255, 0);      // IPAddress DNS(192, 168, 1, 90);          //   WiFiServer server(80);   byte led_brightness = 0 ;   void setup() {     Serial.begin(115200);     pinMode(2, OUTPUT);      // set the LED pin mode           WiFi.config(ip, gateway, subnet, DNS);   // Set fixed IP address     delay(10);       // We start by connecting to a WiFi network -----------------------------     Serial.println();     Serial.print("Connecting to ");     Serial.println(ssid);       WiFi.begin(ssid, password);       while (WiFi.status() != WL_CONNECTED) {         delay(500);         Serial.print(".");     }       Serial.println("");     Serial.println("WiFi connected.");     Serial.print("IP address: ");     Serial.println(WiFi.localIP());           server.begin();       // for LED PWM Control ---------------------------------------------------     sigmaDeltaSetup(0, 312500);    // setup channel 0 with frequency 312500 Hz     sigmaDeltaAttachPin(2,0);      // attach pin 2 to channel 0     sigmaDeltaWrite(0, 0);         // initialize channel 0 to off     }   void loop(){   WiFiClient client = server.available();     // listen for incoming clients   int pos ;   String cmd = "" ;       if (client) {                                               // if you get a client,     Serial.println("***** Client access start *****");       // print a message out the serial port     while (client.connected()) {                              // loop while the client's connected       if (client.available()) {                               // if there's bytes to read from the client,         String line = client.readStringUntil('\n');           // Get Line data until '\n'         Serial.print("client:") ;         Serial.println(line);         if ((pos= line.indexOf("GET /?led_v")) != -1) {           pos += 12 ;           while((line.charAt(pos) >='0') & (line.charAt(pos) <='9')) {             cmd += line.charAt(pos++) ;           }           pos = cmd.toInt() ;           if (pos>256) pos = 255 ;           led_brightness = (byte)pos ;           Serial.print("led_brightness : ");           Serial.println(led_brightness) ;         }         if (line.indexOf("GET /?on") != -1) {                 // Client request was "GET /?on"           if (led_brightness < 80) led_brightness = 80 ;           else if (led_brightness > 245) led_brightness = 255 ;           else led_brightness += 10 ;           Serial.print("led_brightness : ");           Serial.println(led_brightness);         }         if (line.indexOf("GET /?off") != -1) {                // Client request was "GET /?off"           led_brightness = 0 ;           Serial.print("led_brightness : ");           Serial.println(led_brightness);         }         sigmaDeltaWrite(0, led_brightness) ;                  // set PWM value to channel#0           if (line.length() == 1 && line[0] == '\r'){           // end of HTTP request           send_response(client) ;                             // send response to client           break;                                              // break while loop         }       }     }     delay(1);                                        // give the web browser time to receive the data     // close the connection:     client.stop();     Serial.println("Client Disconnected.");     Serial.println("--------------------------------------------------");   } }   // ------------------------------------------------------------------   void send_response(WiFiClient client) {     // 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();     // the content of the HTTP response follows the header:     client.println("<!DOCTYPE html><html lang='ja'><head><meta charset='UTF-8'>" ) ;     client.println("<style>input.button {margin:8px;width:100px;}" ) ;     client.println("       input.button2 {margin-left:8px; width:40px;}" ) ;     client.println("       input.text   {margin-left:8px; width:25px;}" ) ;     client.println("       div   {font-size:16pt;text-align:center;width:250px;border:solid 4px #93ff93;} " ) ;     client.println("       </style>" ) ;     client.println("<title>Color LED Controller</title></head>" ) ;     client.println("" ) ;     client.println("<body><div><p>LED ON/OFF</p>" ) ;     client.println("  <form method='get'style='text-align:left'> " ) ;     client.println("    <span style='padding-left:15pt; font-size:8pt ;text-align:left'> LED brightness (0-255)</span> " ) ;     client.print("    <input class='text'  type='text' name='led_v' value=" ) ;     client.print(led_brightness ) ;     client.println(" width='50px'><input class='button2' type='submit' name='set' value='SET'></form> " ) ;     client.println("  <form method='get'>" ) ;     client.println("    <input class='button' type='submit' name='on' value='ON'><input class='button' type='submit' name='off' value='OFF'></form>" ) ;     client.println("  </div></body>" ) ;     client.println("</html>" ) ;     client.println();     Serial.println( " --- send responce --- "); }

HTML で 入力のテキストボックスを led_v の名前で作成。form の method は 'get'。
loop の中で client からの "GET /?led_v" を見つけたら、後に続く数字<0-9> を取得。
値が 255 を超えたら、255とする。
ON ボタンが押された場合 ("GET /?on") は明るさ を +10 して、押されるたびに明るくなるようにする。