#include <Arduino.h>
#include <HTTPClient.h>
#include <WiFi.h>

#define trig 23
#define echo 21
#define h 100
const char *ssid = "Wokwi-GUEST";
const char *password = "";

String servername = "http://api.thingspeak.com/update?api_key=09IWH8P8UNCT3OKD";
long lastTime = 0, timeDelay = 10000;
long duration, distance;
void readDistance()
{
  digitalWrite(trig,0);
  delayMicroseconds(2);
  digitalWrite(trig,1);
  delayMicroseconds(10);
  digitalWrite(trig,0);

  duration = pulseIn(echo,HIGH);
  distance = h - (duration/58); // don vi cm
}
void setup(){
  Serial.begin(9600);
  WiFi.begin(ssid,password);
  while(WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print("...");
  }
  pinMode(trig,OUTPUT);
  pinMode(echo,INPUT);
}
void loop(){
  if((millis() - lastTime) > timeDelay)
  {
    if(WiFi.status() == WL_CONNECTED)
    {
      readDistance();
      WiFiClient client;
      HTTPClient http;
      String server = servername + "&field1=" + String(distance);
      http.begin(client,server.c_str());
      int httpResponse = http.GET();
      if(httpResponse > 0){
        Serial.println(httpResponse);
      }
      http.end();
    }
    lastTime = millis();
  }
}