Nexus-XR: please add CRSF to the UARTs

[wimalopaan]

Current Behavior

The Nexus-XR has several free UARTs, most of them connected to the JST-GH connectors of the device. But the UARTs could not be configured to CRSF.

Desired Behavior

Please add the possibility to use the UARTs as CRSF ports, mostly like on the ESP32-based ELRS receivers: these can use two UARTs set to CRSF and the receivers routes the messages between them and the OTA connection.

The implementation could follow the ELRS code CRSFRouter implementation.

Who does this impact? Who is this for?

This would be especially usefull for the users of the Nexus-XR: this device contains an internal ELRS receiver. So, it would be nice to connect all kind of CRSF devices (not only telemetry sensors) to one of the JST-GH connectors (CRSF).
This would extend the usage of a Nexus-XR greatly. Otherwise a Nexus-X must be used with an external ESP32-ELRS receiver: one of the serials of the receiver connected to the Nexus-X and the other serial could be used for other CRSF devices. But this is cumbersome, since the Nexus-XR already contains an ELRS-receiver.

[Skuppersixseven]

This is a great suggestion- It would make it quite easy to set up a secondary CRSF device for a ground station

[wimalopaan]

This is also related to #11352

[sensei-hacker]

Do you have Radiomaster CRSF sensors to test with?

[wimalopaan]

Do you have Radiomaster CRSF sensors to test with?

Yes, all of them.

[sensei-hacker]

We will NOT be removing existing features to add bloat that can only be used with your custom board, and by nobody else. In other words, we will not be routing random CRSF packets. As discussed in great detail on the Discord.

[wimalopaan]

I never asked to remove something.

[sensei-hacker]

I never asked to remove something.

Adding stuff means removing stuff - the 512 KB of flash is full.

So your request would actually mean something like "remove Sbus and replace it with code that requires my custom hardware, that nobody else can use".

Better, I think, would be to make your hardware compatible with publicly available hardware such as that sold by Radiomaster. If you'd be interested in doing that:

I know you have done some development with CRSF.
Since you say you have all of the RadioMaster sensors, can you please post the first 14 bytes or so from the GPS sensor and battery sensor so I can make sure we have them right?

It's my understanding that they use a custom proprietary data format, packed inside of an MSP frame, packed inside of a CRSF frame. (As discussed for several hours on Discord).

[sensei-hacker]

If you're interested in Radiomaster support, we can please discuss that #11352

Spending our flash budget (and time) on custom hardware just for one single user that isn't available to anyone else is a non-starter.

[wimalopaan]

If you're interested in Radiomaster support, we can please discuss that #11352

Sure ;-)

Spending our flash budget (and time) on custom hardware just for one single user that isn't available to anyone else is a non-starter.

Well, I was asking for a full CRSF implemetation like e.g. in ELRS.

But - no problem - it's your project, and I was just suggesting something, nothing more.

Having support for CRSF sensors (#11352) would be a great thing!

[wimalopaan]

It's my understanding that they use a custom proprietary data format, packed inside of an MSP frame, packed inside of a CRSF frame. (As discussed for several hours on Discord).

Just for the record: they use plain CRSF (except their config protocol)

[sensei-hacker]

It may be the configuration protocol wrapped in MSP_WRITE. I am trying to get clarification from the Radiomaster engineer, or from someone who actually has the sensors in their possession and can capture the actual bytes to confirm.

[wimalopaan]

It may be the configuration protocol wrapped in MSP_WRITE. I am trying to get clarification from the Radiomaster engineer, or from someone who actually has the sensors in their possession and can capture the actual bytes to confirm.

As I said: sensor data is pure CRSF. Config-read/write is MSP-over-CRSF. So, all in all: CRSF

If you need any data, ping me.

[sensei-hacker]

Fyi I spoke to a Radiomaster engineer today and got some confirmation.