Tuesday, June 13, 2017

ESP32/Arduino core for ESP32 example, simple Web control RGB LED

My former post show how to program ESP32 with Arduino core for ESP32 to output PWM to GPIO using ledcWrite(). This exercise modify from the post of "NodeMCU/ESP8266 Arduino Core example, simple http server to output PWM", port to ESP32/Arduino core for ESP32, to implement a simple web control RGB LED.


NodeMCU32_WebRGBLED.ino
/* 
 *  This sketch run on ESP32 with Arduino core for ESP32,
 *  demonstrates how to set up a simple HTTP-like server.
 *  The server will set a GPIO pins depending on the request,
 *  to control the brightness of RGB LED connected to:
 *    23 : BLUE
 *    22 : GREEN
 *    21 : RED
 *    
 *    http://server_ip/rgb/rrggbb/
 *    where rr is the value set RED
 *    where gg is the value set GREEN
 *    where bb is the value set BLUE
 *    then terminate with '/'
 *  server_ip is the IP address of the ESP32, will be 
 *  printed to Serial when the module is connected.
*/
#include <WiFi.h>

const char* ssid = "ssid";
const char* password = "password";
WiFiServer server(80);

#define MAX_LED_VALUE 99
// use first 3 channels of 16 channels (started from zero)
#define LEDC_CHANNEL_0_R  0
#define LEDC_CHANNEL_1_G  1
#define LEDC_CHANNEL_2_B  2

// use 13 bit precission for LEDC timer
#define LEDC_TIMER_13_BIT  13

// use 5000 Hz as a LEDC base frequency
#define LEDC_BASE_FREQ     5000

// LED PINs
#define LED_PIN_R   21
#define LED_PIN_G   22
#define LED_PIN_B   23

/*
Because Multiple libraries were found for "WiFi.h",
Arduino IDE will: 
 Used: ...\Arduino\hardware\espressif\esp32\libraries\WiFi
 Not used: C:\Program Files (x86)\Arduino\libraries\WiFi

And exit with error:
'min' was not declared in this scope

So I have to program my own min()
 */
uint32_t min(uint32_t num1, uint32_t num2){
  if(num1 < num2){
    return num1;
  }else{
    return num2;
  }
}

// Arduino like analogWrite
// value has to be between 0 and valueMax
void ledcAnalogWrite(uint8_t channel, uint32_t value, uint32_t valueMax = MAX_LED_VALUE) {
  // calculate duty
  uint32_t duty = (LEDC_BASE_FREQ / valueMax) * min(value, valueMax);

  // write duty to LEDC
  ledcWrite(channel, duty);
}

void setup() {
  Serial.begin(115200);
  delay(10);
  
  // Setup timer and attach timer to a led pins
  ledcSetup(LEDC_CHANNEL_0_R, LEDC_BASE_FREQ, LEDC_TIMER_13_BIT);
  ledcAttachPin(LED_PIN_R, LEDC_CHANNEL_0_R);
  ledcSetup(LEDC_CHANNEL_1_G, LEDC_BASE_FREQ, LEDC_TIMER_13_BIT);
  ledcAttachPin(LED_PIN_G, LEDC_CHANNEL_1_G);
  ledcSetup(LEDC_CHANNEL_2_B, LEDC_BASE_FREQ, LEDC_TIMER_13_BIT);
  ledcAttachPin(LED_PIN_B, LEDC_CHANNEL_2_B);

  // Connect to WiFi network
  Serial.println();
  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");
  
  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.println(WiFi.localIP());
}

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }
  
  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }
  
  // Read the first line of the request
  String req = client.readStringUntil('\r');
  Serial.println(req);
  client.flush();
  
  // Match the request
  int valR, valG, valB;
  String subStringR, subStringG, subStringB;
  int index = req.indexOf("/rgb/");
  if(index != -1){
    if(req.charAt(index+11)=='/'){
      subStringR = req.substring(index+5, index+7);
      subStringG = req.substring(index+7, index+9);
      subStringB = req.substring(index+9, index+11);
      Serial.println("R: " + subStringR);
      Serial.println("G: " + subStringG);
      Serial.println("B: " + subStringB);

      valR = subStringR.toInt();
      valG = subStringG.toInt();
      valB = subStringB.toInt();
      Serial.println("valR: " + String(valR));
      Serial.println("valG: " + String(valG));
      Serial.println("valB: " + String(valB));
      
    }
    else{
      Serial.println("Not terminated with /");
      client.stop();
      return;
    }
  }
  else {
    Serial.println("No /rgb/ found");
    client.stop();
    return;
  }

  // Set GPIOs according to the request
  // No check valid of the requested setting
  ledcAnalogWrite(LEDC_CHANNEL_0_R, valR);
  ledcAnalogWrite(LEDC_CHANNEL_1_G, valG);
  ledcAnalogWrite(LEDC_CHANNEL_2_B, valB);
  
  client.flush();

  // Prepare the response
  String s = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nGPIOs of RGB is now ";
  s += String(valR) +":" + String(valG) + ":" + String(valB);
  s += "</html>\n";

  // Send the response to the client
  client.print(s);
  delay(1);
  Serial.println("Client disonnected");

  // The client will actually be disconnected 
  // when the function returns and 'client' object is detroyed
}



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