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:

[PizzaProgram]

About MCP23017:

I've realised there is no "all-in-one" solution to do everything combined.
So I've decided to break into parts:

1. MCP23017 boards will be used with I2C through a AtTiny85 adapter and one of these nodes.
   Sadly I'll loose the INTERRUPT possibility.

2. I'll drop PCF8574 modules. Use Arduino boards directly only.
   (Same price\PIN ratio + shielded USB included. A 7 port USB HUB costs < $5. So it's not worth the trouble.)

3. Temperature reading will be a completely other thing. Maybe with AtTiny85 boards using a safe 1wire PJON system and protocol.

4. As I've said before: I'll drop Firmata. More trouble than reward.

Closing this topic.

Follow possible solutions at the new topic:

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:

[PizzaProgram]

I've created a new ALL-IN-ONE solution for both IO chips to handle everything without i2c bus conflicts:

New MCP23017 PCF8574 All-In-One node

After 14 month of work in my free (and work) time here I present my first AIO solution to handle 3 similar kind of Input-Output I2C chips with Node-Red: I'm still searching a way to publish it to NPM. (Do not know yet, how to "log in" to my NPM account on Rpi terminal to publish...) Please tell your opinion, and report any errors you may find. The main differences to the original 0.1 version: It supports INTERRUPTS read can be triggered -> you get a full JSON of all pins and read success N…

... although it can not handle temp sensors + Arduino USB boards.
For that other methods are needed.