My relay is turning on automatically, when the NodeMCU is rebooting

Ahmad · June 15, 2019, 5:08pm

i have read in a thread: All relay turns on automatically when my nodemcu reboot, that this was solved, but i didn’t really understand how this was solved, i have the same problem, but can you please explain more and how to solve this?
i dont have this in my code:

void setup(){
  Blynk.syncAll();
}

This is the problem?, or it was a local server problem?

Blynk_Coeur · June 15, 2019, 5:18pm

which PIN do you use ?

Ahmad · June 15, 2019, 5:24pm

D7 on NodeMCU

Blynk_Coeur · June 15, 2019, 5:28pm

PIN D7 is GPIO 13
the PIN is High at boot
better use D1 or D2

Ahmad · June 15, 2019, 5:29pm

ohh, so this will solve the problem:

Blynk.syncAll();

??

Blynk_Coeur · June 15, 2019, 5:31pm

this is used to sync virtual pin, not digital one

Ahmad · June 15, 2019, 5:34pm

then how to sync a digital one?

Ahmad · June 15, 2019, 5:34pm

ohh but this will work, cuz the button on the blynk app will sync and turn off the device, right?

Blynk_Coeur · June 15, 2019, 5:35pm

Yes !!

Ahmad · June 15, 2019, 5:37pm

ohhh thanks!!!, i just tried it, but the device is turning on for like less than a sec, and then turning off, is this normal?

Blynk_Coeur · June 15, 2019, 5:38pm

if you use D7 it’s normal ! it’s what I said

Ahmad · June 15, 2019, 5:39pm

ohh ok, niceee, thankss for this info, much appreciated

Blynk_Coeur · June 15, 2019, 5:40pm

Ahmad · June 15, 2019, 5:41pm

niceee, thanks!!

aquarius · June 21, 2019, 5:51pm

Hi Ahmad,
If your problem is not solved yet, may it is a hardware related problem.
In case of you are using a transistor controlled relay, most important to grounding transistor base with ~10k resistor like in this example picture what I have created for you:

I had similar problem with ESP8266 and this helped to solve mentioned issue.
Regards,
aquarius