Blynk automations with a multiplexer aren´t working

[PeteKnight]

@Natalia

create a code that would work with the multiplexor

What type of multiplexor?

@Natalia

#define m3 1
#define m4 3

GPIOs 1 and 3 are a very bad choice of pins…

ESP32 Pinout Reference: Which GPIO pins should you use? | Random Nerd Tutorials

Using this type of board may be a better solution…

ESP8266 16-way relay board using 2x 74HC595 controllers

I saw this post from @Vitokhv recently and decided to order one of these boards and have a play around with it. Here’s a link to another supplier on AliExpress who’s selling the same board: The boards are basically an ESP8266 with two 74HC595 shift registers that allow the 16 onboard relays to be controlled via just 4 GPIOs. They seem to be available in versions that work with a 5v, 12v or 24v supply voltage, and the relays are supposed to be capable of switching up to 250v at 10A each. …

And if you wanted some additional pins for use as physical buttons to control your relays without Blynk, and/or LEDs to indicate the status of each relay then you could daisy-chain multiple MCP23017 boards together to give upto 128 additional GPIOs…

Using the MCP23017 IO Expansion Board

EDIT NOVEMBER 2021… Anyone interested in controlling multiple relays may also want to take a look at this topic, which uses a pre-built 16-way relay board and 2x 74hc595 shift registers: END OF EDIT . I had a project recently where I wanted to use 5 physical buttons, with built-in LED indicators, to control 5 relays. That meant having 15 GPIOs available, so I built the project around an ESP32 dev board. I also needed a few more GPIO pins for other sensors, so by the time I was done I was o…

@Natalia

m1 is my signal pin in the multiplexor and m2 m3 m4 m5 would be s0 s1 s2 s3

I notice that your V4 widget button is writing m2-5 LOW, which would normally turn output D1 on.

Then, your V5 widget button is writing m2 HIGH and m3-5 LOW. This would normally turn output D8 on.

V6 turns m2, m4 and m5 LOW and m3 HIGH, which would normally turn output D4 on.

This assumes that you were correct when you said “m2 m3 m4 m5 would be s0 s1 s2 s3”. Are these multiplexor outputs (D1, D8 & D4) the ones you were expecting to be controlling with these combinations?

Also your else statement in each of these BLYNK_WRITE commands won’t turn the corresponding output off, because you’re not writing anything to the m2-5 pins when you pull your signal pin LOW.

TBH, it’s usually far easier to use a library designed for your multiplexor chip to simplify these data pin combinations, otherwise it all gets very messy when you start dealing with lots of pins.

Also, using the BLYNK_WRITE_DEFAULT() function (as shown in the two examples above) makes your code much neater and simpler.

You should also be careful when using Blynk.syncAll() as this only works with datasterams where you’ve enabled the Sync with latest server value every time device connects to the cloud option in the advanced datastream options. It’s far better to either list the pins you want to sync, or use a for loop to cycle through those pins.

Pete.