Remote Control LEGO Race Car

//****************************************************************
// Make sure to install the AsyncHTTPRequest_Generic and
// dependent libraries before building this.
//****************************************************************

#include <ESP8266WiFi.h>
#include <AsyncHTTPRequest_Generic.h>    // https://github.com/khoih-prog/AsyncHTTPRequest_Generic

#include <Ticker.h>


#define BUTTON_PIN 4
#define QIKEASY_IP_ADDR "192.168.11.122"   // <<----- Change this to the IP address of your QikEasy Virtual Sensor


#define SSID "<YOUR SSID>"
#define WIFIPASSWORD "<YOUR WIFI PASSWORD>"


int previous_button_state = 1;
unsigned long lastDebounceTime = 0;  // the last time the output pin was toggled
unsigned long debounceDelay = 10;    // the debounce time; increase if the output flickers
unsigned long updateSpeedInterval = 200;    // the debounce time; increase if the output flickers
int currentAnalogValue=-1;


#define MaxHttpClientConnection 5

struct concurrentConnection {
  AsyncHTTPRequest *request=NULL; 
  bool available=true;
} concurrentConnection[MaxHttpClientConnection];




// return -1 if no available http client is found
int findAvailableClientIndex() {
  for (int i=0; i<MaxHttpClientConnection; i++)
    if (concurrentConnection[i].available)
      return i;
  return -1;
}

// return -1 if no matching http request client is found
int findClientIndexByAsyncHTTPRequest(AsyncHTTPRequest *pRequest) {
  for (int i=0; i<MaxHttpClientConnection; i++) if (concurrentConnection[i].available == false && concurrentConnection[i].request == pRequest ) return i; return -1; } void requestCB(void* optParm, AsyncHTTPRequest* thisRequest, int readyState) { (void) optParm; if (readyState == readyStateDone) { // Serial.println(F("Response Code = "), request->responseHTTPString());

    if (thisRequest->responseHTTPcode() != 200)
      Serial.println("Response error");
    //else
    //  Serial.println(request->responseText());

    int index=findClientIndexByAsyncHTTPRequest(thisRequest);
    if (index != -1) {
      delete concurrentConnection[index].request;
      concurrentConnection[index].available=true;    
    }
  }
}


void httpRequestToQikEasyAdapter(uint16_t red, bool pressed) {
  static bool requestOpenResult;
    
  if (WiFi.status() == WL_CONNECTED) {
    String url = String("http://") + QIKEASY_IP_ADDR + "/set?t=c&r=" + red + "&g=" + (pressed?1024:0);
    char myUrl[50];
    url.toCharArray( myUrl, 50);

    // Making the request.
    int httpClientIndex = findAvailableClientIndex();
    if (httpClientIndex != -1) {
      // Serial.printf("Connection index = %d\n", httpClientIndex);
      concurrentConnection[httpClientIndex].available=false;
      concurrentConnection[httpClientIndex].request = new AsyncHTTPRequest;
      concurrentConnection[httpClientIndex].request->onReadyStateChange(requestCB);
      requestOpenResult = concurrentConnection[httpClientIndex].request->open("GET", myUrl);
      //Serial.println(myUrl);
      if (requestOpenResult) {
        // Only send() if open() returns true, or crash
        concurrentConnection[httpClientIndex].request->send();
      }
      else
      {
        Serial.println("Can't send bad request");
        delete concurrentConnection[httpClientIndex].request;
        concurrentConnection[httpClientIndex].available=true;
      }
    }
  }
}
  

void setup() {
  Serial.begin(74880);
  WiFi.mode(WIFI_STA);
  WiFi.begin(SSID, WIFIPASSWORD);
  Serial.println("Waiting for Wifi Connection");
  while (WiFi.waitForConnectResult() != WL_CONNECTED) {
    delay(1000);
    ESP.restart();
  }
  Serial.println("Wifi Connected");
  
  pinMode(BUTTON_PIN, INPUT_PULLUP);
}



void loop() {
 int reading = digitalRead(BUTTON_PIN);

  int voltageValue = analogRead(A0);    // range: 500 to 1000, center point = 750
  bool analogValueChanged = ( abs(voltageValue - currentAnalogValue) > 10 );
  
  if ( (reading != previous_button_state && (millis() - lastDebounceTime) > debounceDelay) ||
       (analogValueChanged && (millis() - lastDebounceTime) > updateSpeedInterval) ) {   // keep updating speed when button pressed

      // uint16_t red = (voltageValue-500)*2 + 12;  // For center point=750,  (750-500)*2 + 12 = 512 the desired center point.
      int16_t red = (voltageValue-500)*8 - 1488;     // For center point=750,  (750-500)*8 - 1488 = 512 the desired center point.
      if (red < 0) red = 0; if (red > 1024) red = 1024;

      // NOT PRESSED
      if (reading == HIGH)
        httpRequestToQikEasyAdapter(red, false);

      // PRESSED
      else
        httpRequestToQikEasyAdapter(red, true); 
  

      previous_button_state = reading;
      currentAnalogValue = voltageValue;
      lastDebounceTime = millis();
  }

  delay(100);
}