ESP8266 Community Forum

- Sun Nov 24, 2019 1:08 am #84700 I'm using a WEMOS D+ mini and a hc-sr04 ultrasonic sensor to setup a tank level sensor (with blynk).
My code is based on this first code which works mostly fine (sometimes i get wrong values, but still not nice).

Code: Select all#define echoPin D7 // Echo Pin
#define trigPin D6 // Trigger Pin
 
long duration, distance; // Duration used to calculate distance
 
void setup()
{
Serial.begin (57600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}
 
void loop()
{
/* The following trigPin/echoPin cycle is used to determine the
distance of the nearest object by bouncing soundwaves off of it. */
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
//Calculate the distance (in cm) based on the speed of sound.
distance = duration/58.2;
Serial.println(distance);
//Delay x ms before next reading.
delay(2000);
}

But once I integrate the same code with the blynk part, I only get wrong values.

Code: Select all#define BLYNK_PRINT Serial
#define echoPin D7 // Echo Pin
#define trigPin D6 // Trigger Pin

#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "5vJfspsKEJXnD9YNgBxxxxxxxxxx";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "Toxxxx";
char pass[] = "xxxxx";
 
long duration, distance; // Duration used to calculate distance


BlynkTimer timer;


void setup()
{
Serial.begin (57600);
Blynk.begin(auth, ssid, pass);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
timer.setInterval(1000L, myTimerEvent);
}


// This function sends Arduino's up time every second to Virtual Pin (5).
// In the app, Widget's reading frequency should be set to PUSH. This means
// that you define how often to send data to Blynk App.
void myTimerEvent()
{
  // You can send any value at any time.
  // Please don't send more that 10 values per second.
  Blynk.virtualWrite(V5, distance);
}

void loop()
{

  /* The following trigPin/echoPin cycle is used to determine the
distance of the nearest object by bouncing soundwaves off of it. */
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  //Calculate the distance (in cm) based on the speed of sound.
  distance = duration/58.2;
  Serial.println(distance);
  //Delay x ms before next reading.
  delay(2000);

  Blynk.run();
  timer.run(); // Initiates BlynkTimer
}


It seems to jump in both cases between two values, 115 (the correct one) and 80 (the wrong one).

With the big difference that the first code only has occasional wrong indications, while the second one almost regularly jumps between the two values.....


why is that?

Thanks. Help is muck appreciated!

first code.png

second code.png

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WEMOS D1 Mini/Arduino

- Tue Nov 26, 2019 4:49 am #84733 without blynk, wifi is not running.
without wifi, "uninterruptible" background tasks are relatively quiet and no disruption of pulesIn()
this kind of measurement is very tricky on esp8266.

=> try to keep wifi disabled during measurement