Arduino USB > Firmata > I2C > [GPIO PCF8574 + MCP23017 + temp BMP280]

[PizzaProgram]

@woodlandsolitude

That's interesting, maybe there is a "hidden way" to invert it. I was playing around with Jonny5 a bit

I mean to do it on the .INO file directly at Firmata.
But I gave up to search for it, because other problems would still remain.

@woodlandsolitude

If I may ask, is there another approach you have in mind?

Yes, I've investigating 4 other possibilities, but wanted to post only, if I know more to compare those.
Opened a new topic for that:

MQTT with Arduino Nano + NodeRed

YES, this is exactly the thing I'm looking for! with minimal C, only "forwarding" RAW data from/to all ports and reconnecting if connection lost. doing whatever possible at NodeRed side. My question is: HOW to do that? Currently I'm investigating this: And This: