WiFi control of effect pedals sample code WiFi control of effect pedals sample code

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WiFi control of effect pedals with Arduino/ESP32C3

Sample code

HTML page data to display in web browser: index_html.ino

char index_html[]=
"<html>\n\
<head>\n\
<title>Arduino Seeed XIAO ESP32C3 Controller</title>\n\
<meta name=\"viewport\" content=\"width=device-width\" />\n\
<style type=\"text/css\">\n\
<!--\n\
.style1 {\n\
	font-family: Arial, Helvetica, sans-serif;\n\
	font-size: 18px;\n\
}\n\
-->\n\
</style></head>\n\
<body>\n\
<form action=\"http://esp32.local/setvol\" method=\"get\" class=\"style1\">\n\
  <p>Arduino Seeed XIAO ESP32C3<br>\n\
  Simple Controller Prototype</p>\n\
  <p>EFFECT:<input type=\"text\" name=\"v1\" value=\"128\"/></p>\n\
  <p>FEEDBACK:<input type=\"text\" name=\"v2\" value=\"92\"/></p>\n\
  <p>TIME:<input type=\"text\" name=\"v3\" value=\"188\"/></p>\n\
  <p>----:<input type=\"text\" name=\"v4\" value=\"0\"/></p>\n\
    <br/>\n\
  <p><input type=\"submit\" name=\"sn\" value=\"Send\"/></p>\n\
</form>\n\
</body>\n\
</html>\n";

Arduino program: ESP32C3_HTTPD.ino

/*
  Arduino Web Server simplified version
  
  Device:
      IoT board: Seeed Studio XIAO ESP32C3
      LCD: AQM1602Y
  Usage:
      Access the URL with a web browser,
      http://esp32.local/  <- using mDNS
*/

#include <WiFi.h>
#include <WiFiClient.h>
#include <WebServer.h>
#include <ESPmDNS.h>
#include <HTTPUpdateServer.h>
#include <time.h>

#define JST     3600*9

#ifndef STASSID
#define STASSID "your ssid"
#define STAPSK  "your password"
#endif

#include <Wire.h>
#include <ST7032.h>

#include <EEPROM.h>
#define SIGNATURE "SGNT101"
#define LED1_PIN D7


struct EEPROM_DATA{
    char value1[128];
    char value2[128];
    char check[10]; // ""
};

EEPROM_DATA eeprom;
ST7032 lcd;
const char* host = "esp32-webupdate";
const char* ssid = STASSID;
const char* password = STAPSK;
extern char index_html[];

WebServer httpServer(80);
HTTPUpdateServer httpUpdater;

// Utility: string copy with length limit
void CopyCharByLength(char *org, char *dest, int max_length)
{
  int i=0;
  while(1)
  {
    if(org[i]=='\0') break;
    if(i>=max_length) break;
    dest[i] = org[i];
    i++;
  }
  dest[i] = '\0';
}

// Utility: get real time string HH:MM.SS
void getRTC( char* timestr )
{
  time_t t;
  struct tm *tm;
  t = time(NULL);
  tm = localtime(&t);
  sprintf(timestr, "%02d:%02d.%02d", tm->tm_hour, tm->tm_min, tm->tm_sec);  
}

// Utility: print RTC on LCD
void LcdPrintRTC(void)
{
    // Real time
  char rtcstr[16];
  getRTC(rtcstr);
  lcd.setCursor(0, 1);
  lcd.print(rtcstr); 
}

// Read from EEPROM
int load_eeprom() {
    EEPROM.get<EEPROM_DATA>(0, eeprom);
    if(strcmp(eeprom.check, SIGNATURE)==0)
    {
        Serial.print("Load EEPROM(Value1):");
        Serial.print(eeprom.value1);
        return 1;
    }
    else
    { 
      // Erase buffer memory if signature is wrong
     Serial.print("EEPROM:error, wrong signature\n");
     memset(&eeprom, 0, sizeof(eeprom));
      return 0;
    }
}

// Save to EEPROM
void save_eeprom() {
    strcpy(eeprom.check, SIGNATURE);
    EEPROM.put<EEPROM_DATA>(0, eeprom);
        Serial.print("Save EEPROM(Value1):");
        Serial.println(eeprom.value1);
    EEPROM.commit();
}

// callback when root url accessed
#define HELLO_MESSAGE "Hello from esp32"
void handleRoot() {
   //LED
  digitalWrite(LED1_PIN, HIGH);
  // LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(WiFi.localIP());
  //lcd.setCursor(0, 1);
  //lcd.print("index.html sent");
  LcdPrintRTC();
  
  //httpServer.send(200, "text/plain", HELLO_MESSAGE);
  httpServer.send(200, "text/html", index_html);

  //LED
  digitalWrite(LED1_PIN, LOW);
}

// callback when '/setvol' uri accessed
void handleSetVol() {
   // LCD
  //lcd.setCursor(0, 0);
  //lcd.print(httpServer.uri());
  //LED
  digitalWrite(LED1_PIN, HIGH);

  String message = "Receive params..\n\n";
  message += "URI: ";
  message += httpServer.uri();
  message += "\nMethod: ";
  message += (httpServer.method() == HTTP_GET) ? "GET" : "POST";
  message += "\nArguments: ";
  message += httpServer.args();
  message += "\n";
  for (uint8_t i = 0; i < httpServer.args(); i++) {
    message += " " + httpServer.argName(i) + ": " + httpServer.arg(i) + "\n";
  }
  httpServer.send(404, "text/plain", message);

  // LCD
  String lcdMessage = "";
  lcd.clear();
  lcd.setCursor(0, 0);
  for (uint8_t i = 0; i < httpServer.args(); i++) {
    //lcdMessage += httpServer.argName(i);
    //lcdMessage += "=";
    char tmp[128];
    httpServer.argName(i).toCharArray(tmp, 127);
    if(strcmp(tmp, "sn")!=0){
      lcdMessage += httpServer.arg(i);
      lcdMessage += ",";
    }
  }
  lcd.print(lcdMessage);
  //httpServer.send(404, "text/plain", lcdMessage);

  // Write to EEPROM
  lcdMessage.toCharArray(eeprom.value1, 127);
  eeprom.value1[127]='\0';
  Serial.println(eeprom.value1);
  //CopyCharByLength(message, eeprom.value1, 127);
  save_eeprom();
  //LED
  digitalWrite(LED1_PIN, LOW);
}

// System setup
void setup(void) {
  // digital pin
  pinMode(LED1_PIN, OUTPUT);

  // Serial monitor: start
  Serial.begin(115200);
  Serial.println();
  Serial.println("Booting Sketch...");

  // WiFi: start
  WiFi.mode(WIFI_AP_STA);
  WiFi.begin(ssid, password);
  while (WiFi.waitForConnectResult() != WL_CONNECTED) {
    WiFi.begin(ssid, password);
    Serial.println("WiFi failed, retrying.");
  }

  // WiFi: DNS start  , register "esp32.local" to Multicast Domain Name System(mDNS)  
  MDNS.begin(host);
  if (MDNS.begin("esp32")) {
    Serial.println("mDNS responder started");
  }

  // Time: get JST time
  configTime( JST, 0, "ntp.nict.jp", "ntp.jst.mfeed.ad.jp");

  // Web Server: setup
  httpUpdater.setup(&httpServer);

  // Web Server: handler when root accessed
  httpServer.on("/", handleRoot);
  httpServer.onNotFound(handleRoot);

  // Web Server: handler when /setvol accessed
  httpServer.on("/setvol", handleSetVol);

  // Web Server: launch web server
  httpServer.begin();
  MDNS.addService("http", "tcp", 80);
  Serial.print("HTTPUpdateServer ready! \n");
  Serial.print("http://");
  Serial.println(WiFi.localIP());

  // LCD: setup
  lcd.begin(16, 2); 
  lcd.setContrast(45); 
  lcd.setCursor(0, 0);
  lcd.print(WiFi.localIP());

  // Time: print RTC on LCD
  LcdPrintRTC();

  // EEPROM: start
  memset(&eeprom, 0, sizeof(eeprom));
  EEPROM.begin(1024); 
  load_eeprom();

}

// Event loop
void loop(void) {
  static int counter=0;
  httpServer.handleClient();

  // Blink arrow on LCD to check system alive
  char str_arrow[2] = {0x7e, 0};
  lcd.setCursor(15, 1);
  counter++;
  counter %= 500;
  switch(counter)
  {
    case 0: lcd.print(" "); break;
    case 250: lcd.print(str_arrow); break;
    default: break;
  }
}