Turn off NodeMCU using IC 7404

Hi there
I am currently using two NodeMCUs 12-E with IC 7404. I want to use Blynk app to Turn on one NodeMCU and turn off the another one? Is there any way out?

Using Blynk Cloud Server
and Android 8.1



Blynk obviously can’t control the 7404 ic directly, as the chip isn’t internet connected.
You could add another MCU - maybe an ESP-01, which would control the 7404, which could in turn control the two NodeMCUs.

It may also be possible to get the two NodeMCUs to control each other, but it really depends on what you’re trying to achieve.


Yeah, you got that right. I am trying to control one set of LEDs from one NodeMCU and one set from the other NodeMCU. I have uploaded the code on first NodeMCU for the first set of LEDs and after a desirable time (which is variable), I want the code to stop and control the second set of LEDs from 2nd NodeMCU using Blynk. Any solution for that?

Lots of ways to do this, but once again it’s difficult to know which would be better without more info.

If each MCU was running code with a different Blynk Auth code then they could be controlled separately via the same Blynk project. If you’re using Android then you could use the Eventor widget to switch from one MCU to the other.
Or, you could use Bridge or API code on the two MCUs to do the switching.


Well, let me come to the point

One NodeMCU is running code for traffic lights. It also has Blynk auto token.
The other NodeMCU is being used for Blynk specially and turning off the traffic LEDs and is being used to turn on the other set of LED. I don’t get the code thing…

I don’t really understand why this can’t all be done with just one MCU.

I don’t really understand what it is that you don’t ‘get’ about my references code.
Presumably you’re currently running code on the two MCUs (otherwise what’s the point in having them). If you run Blynk code on both then they should have different Auth codes. If you wnat to controlone device from the other- via Blynk - then you either need to use the Blynk Bridge functionality, or issue an API call to the Blynk server to control one device from the other.

Anyway, I’m done guessing at the details of your setup and playing ‘20 questions’. Share a full and comprehensive description - including diagrams, photos, code etc as required - so that we can understand what your actual requirement/question is.