Compute Module with WiFi for HA Yellow or without WiFi?

Dear all,

Hello first and foremost! As a newcomer I am struggling still a bit with the hardware required for HomeAssistant. I decided for HA Yellow with PoE due to its features (nVME option and on-board Zigbee, Matter, Thread option) . But already there my first question arises, and maybe you can help out:

For the CM4 compute module which needs to be selected, I would have decided the CM4, 8GB RAM variant. Then:

  • no eMMC (since heard that it can wear out, and I do have the nVME Option with yellow, therefore would use that)
  • the main question however which is unclear: Do I need the Compute4 Module with WiFi or Without? Meaning does the Zigbee, Matter, Thread option already include that function which I call “WLAN functionality” or is this something else, since having twice the same functionality is obviously not needed? Since I would like to connect to units connected via a wireless interface and to my knowledge that is done via ESPhome respectively ESP32 chips and similar. And or maybe it is even smart not to have the ComputeModule WiFi Option because it could disturb the Zigbee, Matter… Interface?

Sidenote1: Wherever I can I would use regular LAN to add devices of the home automation system, but there are situations in which ZigBee, Matter etc. devices are required or more convenient.

Best regards,
Tom

Your PoE is connected to your network which has wifi, I assume? That will suffice, you don’t need a separate wifi connection from HA. Having said that I’ve never used a pre-built HA appliance so I can’t offer advice on the eMMC.

Have you considered just getting a rPi kit and separate zigbee dongle? You might end up with more capable hardware and you’re already having to source the brains separately from the kit with the Yellow.

Dear rouxdoo,

thank you for your response. Yes of course the network would have wifi. However there is a “but”. The HA yellow would be put in the cellar, were no good wifi connection would be present. And i currently have not found a good way to connect non LAN devices to LAN unless they would have a RS485 interface (Waveshare RS485 to RJ45 Ethernet Converter Module). And I am dealing with very low level interfaces as in UART with TTL levels in the case of the bitshake smartmeter ( so it would be - if I do not use a ESPchip for that one - a UART conversion to RS485 first and then to LAN).

So I do understand or interpret from your response, that the built-in Zigbee, Matter… interface is not equal to WIFI which could connect to the ESPs, am I interpreting correct? Had hoped the Zigbee, Zwave etc. is just the protocol and therefore it is already wifi built-in. On the other hand I wonder now, can these ESPs do Zigbee, Zwave instead?

The Wifi radio is separate from the Zigbee/Threads radio. Zigbee/Threads (and ZWave) are different than WiFi. The Yellow has a built in Zigbee radio (that can do threads instead). On the Yellow you can either have Zigbee or Threads - not both. Matter is different because it’s a standard that can run over lots of different communications protocol (including Threads and WiFi).

You could get a MC4 module with no Wifi/Bluetooth and be fine. I just built a Yellow, and I went ahead and got one with WiFi/Bluetooth because I wanted the Bluetooth.

As for ESP devices, they would be on WiFi. You would need to have your hardwired Yellow on the same network as your WiFi router in order for the two to communicate. If you’re not sure what that means, what you might need to read up on is networking.

The ESPs need wifi access (and some level of proximity) to your wifi network after you set them up. Setting them up will most easily be done with direct USB access to your HA instance. Out of curiosity why do you plan to place the HA server in such a secluded place? If you want to use zigbee you will need repeaters unless the instance is in proximity to the majority of your devices.

Since you are planning PoE to the HA box, why don’t you backhaul wifi where you want it down in the basement for other things.

Dear Kyle,

thank you for your help! Seems like while reading that the same frequency is (or can be) used for Zigbee with 2.4GHz as for Wireless Network/WLAN I was assuming the base hardware would already be existing with any RF transceiver of this kind, i.e. one of Zigbee which is on the HA yellow).

Ok then I have two tasks now, a) figure out if I can do the same instead of ESP and WiFi but similar for Zigbee or Threads. As in finding the correct mini transceiver with microcontroller which can be added to little sensors and similar. If you can recommend any (or not recommend, due to experience) that is happily taken!

b) check, too due to rouxdoo’s additional message, if it would be smarter to attach either a Matter Controller or Border Router in the cellar instead of the HA yellow or a regular WLAN repeater. Thx for the advice, didn’t think about that!

Best regards,
Thomas