ESP32 上的可变频率 PWM

Question

我一直在研究由 Rui Santos 创建的以下项目，并希望进行一些修改。 ESP32 Web Server Slider

在代码中，频率设置为常量，占空比可通过滑块调节。我想添加一张幻灯片，将频率从 100Hz 调整到 10kHz。

    /*********
  Rui Santos
  Complete project details at https://RandomNerdTutorials.com/esp32-web-server-slider-pwm/
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.
  
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*********/

// Import required libraries
#include <WiFi.h>
#include <AsyncTCP.h>
#include <ESPAsyncWebServer.h>

// Replace with your network credentials
const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

const int output = 2;

String sliderValue = "0";

// setting PWM properties
const int freq = 5000;
const int ledChannel = 0;
const int resolution = 8;

const char* PARAM_INPUT = "value";

// Create AsyncWebServer object on port 80
AsyncWebServer server(80);

const char index_html[] PROGMEM = R"rawliteral(
<!DOCTYPE HTML><html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>ESP Web Server</title>
  <style>
    html {font-family: Arial; display: inline-block; text-align: center;}
    h2 {font-size: 2.3rem;}
    p {font-size: 1.9rem;}
    body {max-width: 400px; margin:0px auto; padding-bottom: 25px;}
    .slider { -webkit-appearance: none; margin: 14px; width: 360px; height: 25px; background: #FFD65C;
      outline: none; -webkit-transition: .2s; transition: opacity .2s;}
    .slider::-webkit-slider-thumb {-webkit-appearance: none; appearance: none; width: 35px; height: 35px; background: #003249; cursor: pointer;}
    .slider::-moz-range-thumb { width: 35px; height: 35px; background: #003249; cursor: pointer; } 
  </style>
</head>
<body>
  <h2>ESP Web Server</h2>
  <p><span id="textSliderValue">%SLIDERVALUE%</span></p>
  <p><input type="range" onchange="updateSliderPWM(this)" id="pwmSlider" min="0" max="255" value="%SLIDERVALUE%" step="1" class="slider"></p>
<script>
function updateSliderPWM(element) {
  var sliderValue = document.getElementById("pwmSlider").value;
  document.getElementById("textSliderValue").innerHTML = sliderValue;
  console.log(sliderValue);
  var xhr = new XMLHttpRequest();
  xhr.open("GET", "/slider?value="+sliderValue, true);
  xhr.send();
}
</script>
</body>
</html>
)rawliteral";

// Replaces placeholder with button section in your web page
String processor(const String& var){
  //Serial.println(var);
  if (var == "SLIDERVALUE"){
    return sliderValue;
  }
  return String();
}

void setup(){
  // Serial port for debugging purposes
  Serial.begin(115200);
  
  // configure LED PWM functionalitites
  ledcSetup(ledChannel, freq, resolution);
  
  // attach the channel to the GPIO to be controlled
  ledcAttachPin(output, ledChannel);
  
  ledcWrite(ledChannel, sliderValue.toInt());

  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi..");
  }

  // Print ESP Local IP Address
  Serial.println(WiFi.localIP());

  // Route for root / web page
  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/html", index_html, processor);
  });

  // Send a GET request to <ESP_IP>/slider?value=<inputMessage>
  server.on("/slider", HTTP_GET, [] (AsyncWebServerRequest *request) {
    String inputMessage;
    // GET input1 value on <ESP_IP>/slider?value=<inputMessage>
    if (request->hasParam(PARAM_INPUT)) {
      inputMessage = request->getParam(PARAM_INPUT)->value();
      sliderValue = inputMessage;
      ledcWrite(ledChannel, sliderValue.toInt());
    }
    else {
      inputMessage = "No message sent";
    }
    Serial.println(inputMessage);
    request->send(200, "text/plain", "OK");
  });
  
  // Start server
  server.begin();
}
  
void loop() {
  
}

Answer 1

    /*********
  Rui Santos
  Complete project details at https://RandomNerdTutorials.com/esp32-web-server-slider-pwm/
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.
  
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*********/

// Import required libraries
#include <WiFi.h>
#include <AsyncTCP.h>
#include <ESPAsyncWebServer.h>

// Replace with your network credentials
const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

const int output = 2;

String sliderValue = "0";

// setting PWM properties
const int freq = 5000;
const int ledChannel = 0;
const int resolution = 8;

const char* PARAM_INPUT = "value";

// Create AsyncWebServer object on port 80
AsyncWebServer server(80);

const char index_html[] PROGMEM = R"rawliteral(
<!DOCTYPE HTML><html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>ESP Web Server</title>
  <style>
    html {font-family: Arial; display: inline-block; text-align: center;}
    h2 {font-size: 2.3rem;}
    p {font-size: 1.9rem;}
    body {max-width: 400px; margin:0px auto; padding-bottom: 25px;}
    .slider { -webkit-appearance: none; margin: 14px; width: 360px; height: 25px; background: #FFD65C;
      outline: none; -webkit-transition: .2s; transition: opacity .2s;}
    .slider::-webkit-slider-thumb {-webkit-appearance: none; appearance: none; width: 35px; height: 35px; background: #003249; cursor: pointer;}
    .slider::-moz-range-thumb { width: 35px; height: 35px; background: #003249; cursor: pointer; } 
  </style>
</head>
<body>
  <h2>ESP Web Server</h2>
  <p><span id="textSliderValue">%SLIDERVALUE%</span></p>
  <p><input type="range" onchange="updateSliderPWM(this)" id="pwmSlider" min="0" max="255" value="%SLIDERVALUE%" step="1" class="slider"></p>
    <p><span id="textSliderValue2">%SLIDERFREQ</span></p>
  <p><input type="range" onchange="updateSliderFREQ(this)" id="freqSlider" min="0" max="255" value="%SLIDERVALUE%" step="1" class="slider"></p>
<script>
function updateSliderPWM(element) {
  var sliderValue = document.getElementById("pwmSlider").value;
  document.getElementById("textSliderValue").innerHTML = sliderValue;
  console.log(sliderValue);
  var xhr = new XMLHttpRequest();
  xhr.open("GET", "/slider?value="+sliderValue, true);
  xhr.send();
}

function updateSliderFREQ(element) {
  var sliderValue = document.getElementById("freqSlider").value;
  document.getElementById("textSliderValue2").innerHTML = sliderValue;
  console.log(sliderValue);
  var xhr = new XMLHttpRequest();
  xhr.open("GET", "/freq?value="+sliderValue, true);
  xhr.send();
}
</script>
</body>
</html>
)rawliteral";

// Replaces placeholder with button section in your web page
String processor(const String& var){
  //Serial.println(var);
  if (var == "SLIDERVALUE"){
    return sliderValue;
  }
  return String();
}

void setup(){
  // Serial port for debugging purposes
  Serial.begin(115200);
  
  // configure LED PWM functionalitites
  ledcSetup(ledChannel, freq, resolution);
  
  // attach the channel to the GPIO to be controlled
  ledcAttachPin(output, ledChannel);
  
  ledcWrite(ledChannel, sliderValue.toInt());

  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi..");
  }

  // Print ESP Local IP Address
  Serial.println(WiFi.localIP());

  // Route for root / web page
  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/html", index_html, processor);
  });

  // Send a GET request to <ESP_IP>/slider?value=<inputMessage>
  server.on("/slider", HTTP_GET, [] (AsyncWebServerRequest *request) {
    String inputMessage;
    // GET input1 value on <ESP_IP>/slider?value=<inputMessage>
    if (request->hasParam(PARAM_INPUT)) {
      inputMessage = request->getParam(PARAM_INPUT)->value();
      sliderValue = inputMessage;
      ledcWrite(ledChannel, sliderValue.toInt());
    }
    else {
      inputMessage = "No message sent";
    }
    Serial.println(inputMessage);
    request->send(200, "text/plain", "OK");
  });
   server.on("/freq", HTTP_GET, [] (AsyncWebServerRequest *request) {
    String inputMessage;
    // GET input1 value on <ESP_IP>/slider?value=<inputMessage>
    if (request->hasParam(PARAM_INPUT)) {
      inputMessage = request->getParam(PARAM_INPUT)->value();
      sliderValue = inputMessage;
      freq = sliderValue.toInt();
    }
    else {
      inputMessage = "No message sent";
    }
    Serial.println(inputMessage);
    request->send(200, "text/plain", "OK");
  });
  // Start server
  server.begin();
}
  
void loop() {
  
}

Answer 2

似乎没有真正记录 ESP32 PWM 的 Arduino 接口，但如果您查看相关的 header and source，您会发现一个函数 ledcChangeFrequency() 似乎可以解决问题。

const double newFreq = ledcChangeFrequency(ledChannel, freq, resolution);
serial.println(newFreq);

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