I have an end device that creates a Pressure cluster that is seen by ZHA as a pressure sensor.
However the pressure cluster only shows values as integers and so I want to use the ‘extended attributes’ for that cluster (as defined in the ZCL spec). When I add them, I can see them in ZHA.
Normally a custom ZHA Device Handler (a.k.a. zha-quirk) is needed to add non-standard clusters and attributes to a device, and therefor it is best to post question like that as a new “device support request” issue to the “ZHA Device Handlers” (a.k.a. zha-quirks) repository on GitHub, see → https://www.home-assistant.io/integrations/zha#how-to-add-support-for-new-and-unsupported-devices
However, not everything can be solved by quirks alone today, and if you want to expose the new type of Zigbee attributes as entities that have previously not been exposed in the ZHA component then it will not be enough with a custom ZHA Device Handler (a.k.a. zha-quirk) as you will also need to extend code for each specific the device type in the zha component inside the Home Assistant core too, see → https://github.com/home-assistant/core/tree/dev/homeassistant/components/zha
There is also a related ongoing discussion among ZHA and zigpy developers on possibly making it possible to extend devices with just quirks alone, so though that is not the case yet, but you can refer to this as well:
I admit that this question may be somewhat similar to the other one I asked recently (about the analog input cluster) and I see that @Hedda’s response appears to be a cut-and-paste of the response there.
By non-standard I primarly mean ” manufacturer specific clusters” which is allowed but can not be predicted since the Zigbee specification is very flexiable around that, but non-standard can mean when a manufactur is not following the Zigbee specifications at all, or simple when it a unusual cluster and attribute that ZHA developers have not previously exposed in the zha component code (as when zha was first created they initially more or less started with just exposing the standard clusters and attributes from the Zigbee Home Automation 1.2 specification, hence the name ”ZHA” of the integration, so it has a legacy to build on, and then later they have exposed more and more as they stumbled onto devices in the wild that use other clusters and attributes).
Again, best is to post a new issue to the ZHA Device Handlers repository to start a discussion with the developers there about if it can be solved via just a new custom quirk for that specific device or if you also nedd to extend the zha component in Home Assistant core as well.
FYI, while ”quirks v2” is still being worked on the initial support for it has been implemented so you can now expose some entities via a new quirk without having to modify ZHA component in HA core, see: