"wired" transport of IR commands

[Onepamopa]

Hey guys,

Wondering if someone has tried this - using an ESP+digital optocoupler, in essence - removing the IR receiver on the AC unit and connecting the optocoupler instead. I think it should work, both the IR receiver and the optocoupler work using the same principle - the ESP would control the LED side, the AC should receive the command on the other end of the optocoupler.

H11L1 or VOH1016AD should (imho) do the job.

Any thoughts?

[crankyoldgit]

The signal is not the same. The library produces (by default) a modulated IR signal, and the devices use a IR "demodulator" typically.

You would need to tell the library to produce a non-modulated signal. see the use_modulation parameter.
e.g.

#include <IRsend.h>

IRsend irsend(4,       // Set the GPIO to be used to sending the message. e.g. D2 on an ESP8266
              false,   // Don't invert the signal.
              false};  // Don't use modulation.

See also: #439 & #438
i.e. You're not the first to have this idea/line of thought, and the library helps you do it. That is, bypassing IR completely and coupling the circuits together to control the device. There are other issues etc where people have successfully done it.

[Onepamopa]

I'm more interested in the actual coupling - is it direct - from the pin on ESP (which is 3.3V) directly with a wire to the "data" pin on the IR receiver on the target device (which could be at 5V), or, as I mentioned - using an optocoupler that can be powered by either 3.3 or 5V on the "receiving" side?

[crankyoldgit]

That's an Electronics/Electrical Engineering/circuit design problem, so out of scope of this library, but others may be able to help. (i.e. I'm lousey at this stuff)
If they were the same voltage, then direct connecting them (inc. tying the GND together) is an option & might work.
If they are different, then using a transistor or a FET which is "switched" by the ESP is an option. Again, the GND needs to connected etc. Or, you could use a logic level shifter.
If you want keep them galvanically separated, then the optocoupler is the better way to go. (and safest)

There are so many ways to solve this problem, and the solution depends on the implementation/design/requirements/available components/cost/etc so it's hard to answer your question.

[Onepamopa]

I've ordered 10x H11L1 & 10x VOH1016AD and will test when they arrive next week. I'll provide enough information here so everyone can find it easier to do the same.

Initially I'll tie the receiving end of the optocopuplers to another NodeMCU and run the "receiver" sketch - to see if what I sent would arrive on the other end in the expected format.

[NiKiZe]

If you can tie and together then the 3.3v out will work fine even on 5v input. But be sure you don't have any pull-ups or similar, so verify voltage first.
But optocopler is always a good option, and there should be no issue handling the frequencies we are talking about here.

[Onepamopa]

The idea is that the optocouplers would completely replace the IR receiver on the units, so they'll all be managed wirelessly from a central location. I've already checked the PCBs on all 7 AC models, Most have 7805CT / L7805 / L7805CV, so 5V @ 1A available to directly power NodeMCU from. I doubt it'd pull more than 250mA with Wi-Fi on.