Do you have experience with more UniPi boards interconnected to have more IO-s?
No, I only have a single board for testing, but generally it would be possible to drive multiple boards through pimatic. The interaction between pimatic-unipi and the UniPi board is based on IP (using WebSockets and HTTP(s)).
Note, however, the current version of the pimatic-unipi plugin can only handle a single unipi board.
Another option for you may be to use an extension board for UniPi base board, e.g. the Relay add-on This option should be supported by pimatic-unipi. Keep also in mind you can have more input/ouputs via the I2C and the 1wire serial busses. You should be able to handle up to 16 devices on each bus. Theoretically you can do more, but you may electrical issues with the lines (Capacitance of the lines, essentially) with long cables, in particular. See the following article on cable length for 1wire.
Can you please explain me how can be this done? (hardware and software)
Assuming an extended version of the pimatic-unipi plugin to handle multiple UniPi boards a setup could be as follows:
- two UniPi boards where each boards has its own Raspi hooked on top of it. The Raspis will be connected to the LAN (or WLAN) and run the Evok software - https://github.com/UniPiTechnology/evok
- one of the Raspis may host Pimatic with the pimatic-unipi plugin to drive both boards through pimatic. This will also work for more than two UniPis and, of course, it is also possible to setup pimatic on a seperate Raspi.
Perhaps i need 3 UniPI-s. One must be a master, and 2 in slave mode or something similar?
I need one single web interface - in this case pimatic - to control all the IO ports from the 3 boards. The Mervis software is a need, or UniPi can be configured without?
You don’t need Mervis. The pimatic-unipi plugin is based on Evok - https://github.com/UniPiTechnology/evok which is open source. Evok is fairly easy to install.