Virtual button to control relay on GPIO 16

[Uzzy]

I’m trying to build a project to turn on a relay for 10 seconds when a virtual (push type) button on v0 is pressed
hardware - ESP8266
relay is connected to GPIO16(D0)
im using the blynk Edgent_ESP8266 code

[PeteKnight]

You should read this…

Using Virtual Pins to control physical devices

I thought I’d write a guide about how to use virtual pins with app widgets such as buttons, to control physical devices such as relays, LEDs etc… Why use virtual pins anyway? I’d always recommend using virtual pins over physical pins when developing your code. There are a number of reasons, but here are what I consider to be the main ones: Virtual pins are hardware independent. This means that it’s far easier to port your code from one hardware platform to another in future (when you realise…

And this…

Using BlynkTimer or SimpleTimer

Many users seem to struggle with the basic concepts of using BlynkTimer in their projects, despite the excellent discussions and tutorials that exist on this forum, so I thought I’d write a guide that will hopefully help clarify things. It’s rather long, as it attempts to explain the reasoning behind why and how we use timers, and covers some more advanced subjects, but I’ve tried to organise it in a way that helps people to find answers to specific questions… Why use a timer at all? Let’s say …

and pay particular attention to the bit about timeout timers.

Pete.

[Uzzy]

thanks for the help.
I read the articles, and this was what i came up with

#define BLYNK_TEMPLATE_ID ""
#define BLYNK_DEVICE_NAME ""
#define BLYNK_FIRMWARE_VERSION        "1.0"

#define BLYNK_PRINT Serial
//#define BLYNK_DEBUG

#define APP_DEBUG
int wifists=2;
#include "BlynkEdgent.h"
#define USE_NODE_MCU_BOARD

BLYNK_WRITE(V0)
{
  int pin = param.asInt();
  if (param.asInt()){
  digitalWrite(16, LOW);
  timer.setTimeout(10000L, [] () {digitalWrite(16, HIGH);} );
  } else {
  digitalWrite(16, HIGH);  
  }
}

void setup() {
  Serial.begin(115200);
  delay(100);
  pinMode(16, OUTPUT);
  pinMode(wifists, OUTPUT);
  digitalWrite(16,HIGH);
  BlynkEdgent.begin();
}
BLYNK_CONNECTED()
{
 
}
void loop() {
  BlynkEdgent.run();
  timer.run();
  
  if (Blynk.connected()) {
    digitalWrite(wifists, HIGH);//turn on wifi status led if device isconnected to internet
  } else {
    digitalWrite(wifists, LOW);
  }

}

the code works fine now, just that the button stays on even after 10 secs;though the relay turns off at 10 secs
i need the relay to stay on for 10 secs no matter how long i press the button for
TIA

[John93]

@Uzzy

the button stays on even after 10 secs

You should update the button status using the Blynk.virtualWrite function.

You can also try automation

Automations

[Uzzy]

Thanks, works now :). Is there any way to adjust the time interval of the delay of the timer using any widgets on the dashboard?
TIA

[PeteKnight]

@Uzzy

Is there any way to adjust the time interval of the delay of the timer using any widgets on the dashboard?

Yes, you can use a parameter as the timeout period, maybe set from a slider or numeric input widget.

Pete.

[Uzzy]

any example code for this?

[PeteKnight]

There’s a snippet of code in the BltnkTimer link I provided earlier.

Pete.

[Uzzy]

BLYNK_WRITE(V0)
{
  
  int pin = param.asInt();
  if (param.asInt()){
  digitalWrite(16, LOW);
  timer.setTimeout(10000L, [] () {digitalWrite(16, HIGH);Blynk.virtualWrite(V0,LOW);} ); //<--- What is the purpose of the "L" after timer.setTimeout(10000 
  } else {
  digitalWrite(16, HIGH);  
  }

}

What is the purpose of the “L” after timer.setTimeout(10000

[PeteKnight]

It defines it as a long Integer.

Pete.

[Uzzy]

i had tried it without the L and it worked the same way ; does it make any difference

[Uzzy]

#define BLYNK_DEVICE_NAME ""
#define BLYNK_FIRMWARE_VERSION        "1.0"

#define BLYNK_PRINT Serial
//#define BLYNK_DEBUG

#define APP_DEBUG
int wifists=2;
#include "BlynkEdgent.h"
#define USE_NODE_MCU_BOARD

BLYNK_WRITE(V7)
{
 int slider = param.asInt();
}
  

BLYNK_WRITE(V0)
{
  
  int pin = param.asInt();
  if (param.asInt()){
  digitalWrite(16, LOW);
  timer.setTimeout(slider, [] () {digitalWrite(16, HIGH);Blynk.virtualWrite(V0,LOW);} );
  } else {
  digitalWrite(16, HIGH);  
  }

}


void setup() {
  Serial.begin(115200);
  delay(100);
  pinMode(16, OUTPUT);
  pinMode(wifists, OUTPUT);
  digitalWrite(16,HIGH);
  BlynkEdgent.begin();
}
BLYNK_CONNECTED()
{
 
}
void loop() {
  BlynkEdgent.run();
  timer.run();
  
  if (Blynk.connected()) {
    digitalWrite(wifists, HIGH);//turn on wifi status led if device isconnected to internet
  } else {
    digitalWrite(wifists, LOW);
  }

}```
This is my updated code.... it doesnt compile and gives the error " 'slider' was not declared in this scope"

[John93]

int typically stores integers in the range of -2147483648 to 2147483647 and requires 4 bytes (32 bits) of memory.
long int can store integers in the range of -9223372036854775808 to 9223372036854775807 and requires 8 bytes (64 bits) of memory.

[John93]

@Uzzy

int slider = param.asInt();

The slider is a local variable. A local variable is a variable that is declared inside a function or a block of code, and it can only be accessed within that function or block. You should use global variable instead.

[Uzzy]

soo… where should i include the slider variable

[John93]

Outside the function.

[Uzzy]

can you please explain further

sorry im new to these stuff

[PeteKnight]

@Uzzy

int slider = param.asInt();

Declaring this as an integer within a function means that its value will always be zero outside of that function, because it’s a local variable.

@Uzzy

if (Blynk.connected()) {
    digitalWrite(wifists, HIGH);//turn on wifi status led if device isconnected to internet
  } else {
    digitalWrite(wifists, LOW);
  }

What is this doing in your void loop?

Pete.

[John93]

Int slider;

BLYNK_WRITE(V7)
{
 slider = param.asInt();
}

[Uzzy]

Thats to turn on a led if the esp is connected to the server