I2C firmware for Johnny-Five Expander

Hello all, Im having trouble understanding how the Johnny-Five "CD74HC4067" expander works. I see that there is a firmware file located in the github repo under johnny-five/firmware. I don't know if i should install this file separately on the nano "backpack", or if its installed when i did my johnny-five installation. Can i just hook things up as wired in the docs and install StandardFirmataPlus on both the nano and uno? Or is there another step(s) I'm missing?

I have no idea what you mean :frowning:

CD74HC4067 is a chip that you can wire to an Arduino. It's not related to I2C at all.

Did you find code that emulates such a chip, or interacts with it, or what?

Some links to the repo and related documentation were helpful.

I am not exactly sure what you are asking. The Johnny-Five "CD74HC4067" expander utilizes a CD74HC4067 device which has 16 digitally controlled analog switches. The 16 switches are connected to 16 individual inputs which when turned on connect to a single output. This allow you to have 16 analog channel inputs utilizing only one analog pin on the Arduino. It will also switch digital signals if so desired. These are by-directional so they pass in either direction. The switch selection is determined by a binary pattern on S0 --- S3. This will only allow one switch to be on at any given time. It also has an active low Enable pin, this has to be low so the unit can turn on and pass the signal. They operate in Break-Before-Make” Switching mode. If it operated on a Make-Before-Break it would connect two inputs together during the switching transition, this does not do this. I would operate this without a driver. Simply connect the enable pin to ground or uhttps://www.ti.com/lit/ds/symlink/cd74hc4067.pdfse an I/O pin to control it, Select whatever channel I wanted using S0 - S3 and read the output on one of the analog channels. Normally when a digital signal has a bar over it it typically indicates it is active low. Here is a link for you: https://www.ti.com/lit/ds/symlink/cd74hc4067.pdf.
Good Luck, & Have Fun!
Gil