#include <WiFiManager.h>

const long sampleWindow = 50; // Sample window width in mS (50 mS = 20Hz)
unsigned int sample;

WiFiManager wifi;

void setup()
{
  Serial.begin(115200);
  if (!wifi.autoConnect("esp_test"))
  {
    Serial.println("not connected");
  }
}


unsigned long millisConnected; // Last time connected
unsigned long startMillis;  // Start of sample window
unsigned int peakToPeak;    // peak-to-peak level
unsigned int signalMax;
unsigned int signalMin;


void loop()
{
  if (WiFi.status() != WL_CONNECTED)
  {
    Serial.print("not connected");
    while(WiFi.status() != WL_CONNECTED)
    {
        Serial.print(".");
        delay(500);
    }
    millisConnected = millis();
    Serial.println();
  }

  startMillis = millis();
  peakToPeak = 0;
  signalMax = 0;
  signalMin = 1024;
  
  // collect data for 50 mS
  while (millis() - startMillis < sampleWindow)
  {
    sample = analogRead(A0);
    // coment out delay(3) below
    // and check on serial monitor 
    // if Wi-Fi connection 
    // is not being lost and then recovered 
    // every half a dozen or so seconds
    delay(3);
    if (sample < 1024)  // toss out spurious readings
    {
      if (sample > signalMax)
      {
        signalMax = sample;  // save just the max levels
      }
      else if (sample < signalMin)
      {
        signalMin = sample;  // save just the min levels
      }
    }
  }
  peakToPeak = signalMax - signalMin;  // max - min = peak-peak amplitude
  double volts = (peakToPeak * 3.3) / 1024;  // convert to volts
  Serial.print((millis()-millisConnected)/1000);
  Serial.print(" ");
  Serial.println(peakToPeak);
}