Raspberry Node.js Virtual Pin reboot state

Need Help With My Project
1 
var Blynk = require('blynk-library');
var AUTH = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxpm2 ';
var blynk = new Blynk.Blynk(AUTH, options = {
 connector : new Blynk.TcpClient()
});
var Gpio = require('onoff').Gpio,
  relay = new Gpio(23, 'out');  // Pi BCM # 23

var v2 = new blynk.VirtualPin(2);  // virtual pin to control GPIO 23

v2.on('write', function() {
        if(relay.readSync() == 0) {  // toggle gpio 23 from high to low
                relay.writeSync(1);
        }
        else {
                relay.writeSync(0);
        }
});

When i use above code everything is ok,but when i restart Rpi and after Blynk connect to cloud my relay state go HIGH…can this behavior change to LOW?

2

That is more due to the nature of the device, musch like as on ESP… but you can try adding in a sync command to reset it upon boot to whatever last server value was.

blynk.on('connect', function() {
  console.log("Blynk ready.");
  //blynk.syncAll();
  blynk.syncVirtual(2);
});
3

I try this…go HIGH for moment and then LOW…i need to avoid that moment :slight_smile:

4

I guess you can ask on the RPi forum if there is any way of changing the nature of the hardware…

Change to a different GPIO, add additional PULL DOWN resistors, wire your relay differently, perhaps add in a capacitor/resistor to the pin output that might smooth out the brief bump without triggering the relay, etc.

Basically I don’t see this as a Blynk related issue… hardware does what it is built to do, and some GPIOs boot or pulse HIGH.

5

How you then explain that when i use plain digital pin(gpio) (NO VIRTUAL) state is LOW?
And is LOW on ANY GPIO.

6

Possibly due to how you have coded it? It is not my code :wink: so I haven’t really tried to figure out what you are doing or why you are doing it that way ;)… I was just explaining that sometimes GPIO pins boot high… if that is not your case, then it is your code.

I would toggle the pin this way (untested)

v2.on('write', function(param) {
        if (param == 1) {  // If Button HIGH
                relay.write(1);
        }
        else if (param == 0) {  // If Button LOW
                relay.write(0);
        }
});
7

Thanks @Gunner but still the same…when i reboot pin goes HIGH :frowning:

8

Read the link to the RPi site… it just may be the way it is??

9

As per that link… According to page 102 of this document, GPIO23 is pulled LOW… does your relay trigger on a LOW or a HIGH signal?

10

Yes i read already…but if that is the case,i dont understand why is hapening only when i try VIRTUAL pin…
My relay is trigering on a HIGH signal (i have led indicator)

11

Well, first off the Virtual pin has NO direct effect on the device. So, perhaps your relay = new Gpio(23, 'out'); // Pi BCM # 23 is doing something??

Or how your GPIO library works?

There are also other variations of GPIO control libraries to experiment with… I am using pigpio