Hi,

I fly FPV wing using a Jeti radio and DJI Digital goggles. The aim is to have OSD info. in the goggles and this is done using the new DJI update and connecting the Air Unit to F405 FC.


It turns out serial comm with this Jeti radio is via EX-Bus only. (Jeti says: PPM, UDI, S.BUS and EX-Bus. Serial communication including internal stabilization is EX-Bus only. ) which isn't one of the supported protocols. 

So question is: can I use an FrSky receiver by itself without purchasing and binding a transmitter where the FrSky is connected to the F405?

So that OSD info. is received in the goggles.

Thanks for any assistance. 

I'm a bit confused about your setup and why you are looking to use a second receiver because it's not the receiver that puts OSD in the goggles. OSD information comes from the flight controller and is sent to the DJI Air Unit over an MSP connection which then transmits that data to the DJI FPV Goggles. So you don't need another receiver to add OSD capabilities.

Maybe an overview of your complete setup and all the components you are using and how you have wired it up would be helpful. Photos showing the wiring would be good.

(15-Apr-2020, 11:48 AM)SnowLeopardFPV Wrote: I'm a bit confused about your setup and why you are looking to use a second receiver because it's not the receiver that puts OSD in the goggles. OSD information comes from the flight controller and is sent to the DJI Air Unitover an MSP connection which then transmits that data to the DJI FPV Goggles. So you don't need another receiver to add OSD capabilities.

Maybe an overview of your complete setup and all the components you are using and how you have wired it up would be helpful. Photos showing the wiring would be good.

I don't have the gear where I am at the moment. Was going to follow this:

https://oscarliang.com/setup-frsky-fport/

You're saying that for OSD only I don't need the receiver. Just the FC plugged into Air Unit? 

Hmm that seems rather obvious now I think about it... Long day. Apologies.

(15-Apr-2020, 12:58 PM)MartinH Wrote: I don't have the gear where I am at the moment. Was going to follow this:

https://oscarliang.com/setup-frsky-fport/

You're saying that for OSD only I don't need the receiver. Just the FC plugged into Air Unit? 

Hmm that seems rather obvious now I think about it... Long day. Apologies.

That article by Oscar is about telemetry data from the FC to a transmitter, so you can up triggers and other things based on telemetry data such as audio call-outs for low voltage and low RSSI, or to log things like GPS co-ordinates on your radio. And for that to work you need a telemetry capable receiver that is actually compatible with and bound to the transmitter. That telemetry data has nothing to do with data you see on the OSD.

The only thing you might not get if your transmitter and receiver don't support it, is RSSI data for the transmitter-receiver link. The RSSI data has to come from the receiver and it can only come from a receiver that has a transmitter connected to it.

What Jeti transmitter and receiver models are you using?

(15-Apr-2020, 01:15 PM)SnowLeopardFPV Wrote: That article by Oscar is about telemetry data from the FC to a transmitter, so you can up triggers and other things based on telemetry data such as audio call-outs for low voltage and low RSSI, or to log things like GPS co-ordinates on your radio. And for that to work you need a telemetry capable receiver that is actually compatible with and bound to the transmitter. That telemetry data has nothing to do with data you see on the OSD.

The only thing you might not get if your transmitter and receiver don't support it, is RSSI data for the transmitter-receiver link. The RSSI data has to come from the receiver and it can only come from a receiver that has a transmitter connected to it.

What Jeti transmitter and receiver models are you using?

Transmitter Jeti DS12 and Receiver Jeti Rex 7 ASSIST (https://www.modelflight.com.au/media/wys...01-web.pdf)

Thank you very much. It's now a lot clearer. I could configure the Jeti to announce low RSSI.

OK, I can see that the Jeti Rex 7 ASSIST receiver is a completely different beast to what we're used to on here, but it appears to output the standard SBUS protocol on the E1 or E2 connections which you can just hook up to the SBUS connection pad on an F405 FC, so I guess this is how you have it connected.

The SBUS protocol by definition can carry RSSI data as long as the receiver provides that data to the FC on one of the channels either directly from the receiver, or over-the-air from the transmitter itself if you're able to configure the transmitter to broadcast the RSSI value on one of the channels. It's not clear if your Jeti transmitter or receiver can be configured to do either of those. If you're familiar with the Jeti gear then you will know more about that than what I' have managed to glean from the internet.

The other way to get RSSI data to the FC is via an analogue RSSI connection from the receiver to the RSSI pad on the FC (I assume you're using a Matek F405-WING FC), but I don't see an analogue RSSI output pin the Jeti Rex 7 so that's probably a no-go. If neither of the aforementioned are an option, then it sounds like you at least have the ability to set up audible RSSI warnings on your transmitter anyway.

(15-Apr-2020, 02:15 PM)SnowLeopardFPV Wrote: OK, I can see that the Jeti Rex 7 ASSIST receiver is a completely different beast to what we're used to on here, but it appears to output the standard SBUS protocol on the E1 or E2 connections which you can just hook up to the SBUS connection pad on an F405 FC, so I guess this is how you have it connected.

The SBUS protocol by definition can carry RSSI data as long as the receiver provides that data to the FC on one of the channels either directly from the receiver, or over-the-air from the transmitter itself if you're able to configure the transmitter to broadcast the RSSI value on one of the channels. It's not clear if your Jeti transmitter or receiver can be configured to do either of those. If you're familiar with the Jeti gear then you will know more about that than what I' have managed to glean from the internet.

The other way to get RSSI data to the FC is via an analogue RSSI connection from the receiver to the RSSI pad on the FC (I assume you're using a Matek F405-WING FC), but I don't see an analogue RSSI output pin the Jeti Rex 7 so that's probably a no-go. If neither of the aforementioned are an option, then it sounds like you at least have the ability to set up audible RSSI warnings on your transmitter anyway.

Great, thank you. That's very helpful.