Raspberry Pi Problems, can read digital but cannot create virtual pins

Hardware and Blynk Libraries
1

I can read and control pins using the application on the phone. For example, I can blink and LED. But I cannot create virtual pins in my C code on the Pi. That is, I want the LED display to show on the phone as a result of the data created in my C code that toggles a virtual pin on the Pi.

#include "wiringPi.h"

#include "Blynk/BlynkApi.h"

int x=0;

int main (void)
{
wiringPiSetup () ;
//pinMode (11, INPUT) ;
for (;:wink:
{

Blynk.virtualWrite (1, HIGH) ; delay (500) ;
Blynk.virutalWrite (1, LOW) ; delay (500) ;
}
return 0 ;
}

When I try to compile, I get an error that Blynk is not declared in this scope.

Please help, perhaps with a sample.
What I want to do is set a virtiual pin High on the Pi, and then have it display an LED on the Blynk Phone app. THANKS.

3

@neoteric, I hope you solved your problem :wink:

4

No, I did not resolve it.
I just can’t seem to get it to work.

Anybody have an idea?

5

The code I see looks wrong. I don’t see the “Blynk.run();” call + many other things.

Please make sure you’re running unmodified main.cpp file and library files to see if it works.
You can find instructions how to build Blynk on Raspberry here: https://github.com/blynkkk/blynk-library/blob/master/docs/Platforms.md#linux-raspberry-pi
If you have problems, please provide detailed information (commands, program output, etc)

Thanks!

6

did you read my issue? *I can run Blynk on the Pi. as described in the instructions. However, what I want to do is write a c program that sets a virtual pin, and display it on my phone.

  1. Cannot figure out simple code to have the pi set a value on a virtual pin, and have it display in the blynk app on the phone.
  2. How long would it take you to point me to an example of that, or show a line of code that does that.

PS, Just a little help please. I have put two days into this and am an not a complete newbie

7

PS, that above post does not come off as nice as I intended. I did not intend it to sound mean.

Thanks.

8

OK FOr those that need to know how, here is an example that sets virtual pin 5 to 255!

/**
 * @file       main.cpp
 * @author     Volodymyr Shymanskyy
 * @license    This project is released under the MIT License (MIT)
 * @copyright  Copyright (c) 2015 Volodymyr Shymanskyy
 * @date       Mar 2015
 * @brief
 */

//#define BLYNK_DEBUG
#define BLYNK_PRINT stdout
#ifdef RASPBERRY
 #include <BlynkApiWiringPi.h>
#else
 #include <BlynkApiLinux.h>
#endif
#include <BlynkSocket.h>
#include <BlynkOptionsParser.h>

static BlynkTransportSocket _blynkTransport;
BlynkSocket Blynk(_blynkTransport);

BLYNK_WRITE(1)
{
  BLYNK_LOG("Got a value: %s", param[0].asStr());
}

int main(int argc, char* argv[])
{
    const char *auth, *serv, *port;
    parse_options(argc, argv, auth, serv, port);

    Blynk.begin(auth, serv, port);

    while(true) {
        Blynk.virtualWrite(5, 255);
        Blynk.run();
    }

    return 0;
}
9

Just a question: My rpi is working with blynk but I don’t see how to control it. Do I have to make a new script or something? I can run the app on the phone and the server on the pi and it just sits there as if waiting for something.

10

He all,

We understand that coding in C++ for Raspberry pi may be not the best idea, so we a already thinking about providing a Python library… I’m personally very interested in this.

What do you think?

3 Likes
11

I would love a Python library :slight_smile:

12
  1. Backup the blynk-libraries folder.
  2. Go into the linux folder in the blynk libraryies folder.
  3. Modify main.cpp, as I did above. In the simple example above, I am setting a virtual pin to a value.
  4. type “make clean all target=raspberry” into the command line to remake it.

Use the examples, that are written for Arduino, to guide you.
As you can tell from my earlier posts, this is not how I thought it worked originally.

3 Likes
13

I would very much appreciate a library for python

14

thanks for the steps, i followed them and it is working.
would you please explain how to use the examples written for arduino ? i want to use the lcd widget or i want to use LDR to show some value in the app?

thank you.

15

Hi all, we now have a JavaScript library, which should make creating virtual pins on Raspberry really simple.
Just check this instructable:

16

Hi,
I’m using raspberry pi for my project. Is there a way where I can send data through I2C from virtual pin. I mean is there a particular file in blynk library for a particular virtual pin/ a file where I can edit all virtual pins ? So that I need not do anything apart from concentrating on my virtual pin.
If not, then how to call a virtual pin to do a particular task be it a internal software task or hardware one.

17

It can be done only via Node.js Blynk library

Here are some examples: