Daisy chaining CM4 devices with a Turing Pi 2.5

Question

I want to build a Cyberdeck that runs off CM4s, and I want to be able to have add-on boards. Say, one board to control all the other add on boards, maybe another one to run a Minecraft server etc.

Originally I was thinking of just clustering them together but I would prefer to not have a networking switch in there. And then I discovered the Turing Pi 2.5, but I want to be able to have more then four CM4s plugged in at once as that would limit me to three add-ons running at a time.

Is this possible?

Say I buy two Turing Pi devices. Can the second Turing Pi get Ethernet from the first if I run an Ethernet cable from the second port of the first one to the first port of the second? I just heard somewhere that you should never plug in the second port while the first port is plugged in cause the switch is in bridged mode.

Answer 1

Definitely possible

Yes, buy another (i.e. two or more) Turing Pi and chain them together (via the Ethernet ports).

The onboard Ethernet is just a two port Ethernet switch. Consider it as such, and use accordingly. That is to say, that you can connect one of the Ethernet ports from one Turing Pi to one of the Ethernet ports on the other Turing Pi - so as to daisy-chain them together.

The fact that the ports are, by default, bridged, is of no real concern to you nor other external devices - the ports can still be used as if they were two Ethernet switch ports.

For further information about the bridged nature of the ports, read Trying to understand why Turing Pi 2’s network jacks are bridged.

The Ethernet switch on the Turing Pi is a managed switch so you can reconfigure it, if you really need to.

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Alternatives

As an alternative to consider, the Super 6C, can take 6 CMs and you don't need the annoying adapter plates that the Turing Pi requires. Also, each "bay" on the Super 6C has access to its own M.2 slot, which the Turing Pi does not. On the Turing Pi, only one slot has access to the single M.2 slot.

On the other hand, the Ethernet switch on the Turing Pi is slightly more configurable than that on the Super 6C.

In both cases, the Ethernet is just two port Ethernet switches, on each board. Consider them as such, and use accordingly.

You could add just one extra CM to each of the above, via the use of a CM IO Board, and connect it via the second Ethernet port - thus still avoiding the need for an additional network switch.

You could also consider a CloverPi, which takes full-size Pi devices, rather than CMs. It also has a built in Ethernet switch.