Basic HCSR04 Data to Blynk Value Widget Example

// Basic HCSR04 Data to Blynk Value Widget Example
// jasper_fracture // jasperfracture.com

#include <BlynkSimpleEsp8266.h>

char auth[] = "your_blynk_token_here";
char ssid[] = "your_wifi_ssid_here";
char pass[] = "your_wifi_password_here";

// gpio pins for the ultrasonic sensor
const int trigPin = 12;  // pin D6 on board
const int echoPin = 13;  // pin D7 on board

void setup()
{
  // put your setup code here, to run once:
  Blynk.begin(auth, ssid, pass);
}

void loop()
{
  // put your main code here, to run repeatedly:
  Blynk.run();
}

// your basic HCSR04 code to return value in inches
// much of this code was borrowed from the Ping example
int checkFront()
{
  long duration, inches;
  pinMode(trigPin, OUTPUT);
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  pinMode(echoPin, INPUT);
  duration = pulseIn(echoPin, HIGH);
  inches = microsecondsToInches(duration);
  return inches;
}

long microsecondsToInches(long microseconds) { return microseconds / 74 / 2; }

//  Blynk function to push data to your phone app through V1
//  Be sure to set up a "Value Display M" or something similar in your app
//  Give the widget a label, set the input to V1, and set the reading frequency to something like 500 ms
//  The Blynk "virtualWrite" function will keep the data on your phone in synch with the hardware every .5 seconds
BLYNK_READ(V1)
{
  Blynk.virtualWrite(V1, checkFront());
}