Hi guys,

recently I've switched to Frsky and need to replace RXs in my quads. First one is Eachine X220S (220mm wheelbase) and the other is Mantis (85mm wheelbase).

TX is Taranis X9D Plus.

I'd like to have a signal strength and battery voltage transfer between the RX and TX if possible (probably not necessary by the smaller quad). I have no use for PWM outputs so this is quite pointless to have. 

I know about Oscar's article about RXs used in mini quads but still I cannot decide. Which ones do you use or recommend and why?

Thanks.

R-XSR or FM+

Get the XSR, they are the best value RX right now and reportedly they have better range than R-XSR, though i don't see the difference myself.
If you want something smaller with Smartport: R-XSR.

XSR-M Micro also has Smartport, telemetry, 2 removable antennas and is very light/small.

R-XSR. Range has not been an issue.

Ok, thank you guys. I've ordered the XSR for 5" and it will probably be R-XSR for my 3" in the future (after I solve some problems with it first lol).

Guys, how is it with ext. voltage monitoring with the X8R and XSR receivers? My friend has unused MLVSS voltage sensor and would give it to me for free. But both of these RXs provide "RX bat voltage monitoring". I assume this is not ext. voltage monitoring, but only provides the RX input voltage monitoring? Is it possible to let my Taranis show main LiPo voltage somehow with these receivers without ext. sensors? Or do I have to use ext. sensors for this purpose?

Many thanks.

(16-Jun-2018, 09:26 AM)czdraconis Wrote: Guys, how is it with ext. voltage monitoring with the X8R and XSR receivers? My friend has unused MLVSS voltage sensor and would give it to me for free. But both of these RXs provide "RX bat voltage monitoring". I assume this is not ext. voltage monitoring, but only provides the RX input voltage monitoring? Is it possible to let my Taranis show main LiPo voltage somehow with these receivers without ext. sensors? Or do I have to use ext. sensors for this purpose?

Many thanks.

Your flight controller should be able to detect LiPo voltage, and feed that info to your receiver using "SmartPort" telemetry.

There is no need to any external sensor to monitor battery voltage as long as your FC can do it.

Here is how to confirm if your FC is detecting battery voltage:
Remove props, connect FC to Betaflight configurator, plug in LiPo battery, and check here:



If you need help setting up SmartPort telemetry here is a guide:
https://oscarliang.com/sbus-smartport-telemetry-naze32/

Thanks Oscar. My Omnibus F4 V3 can do this for sure, but I'm not sure about the Naza M V2 as there is a separate PMU (Power Management Unit). And my DJI F550 is the main reason I'd like to use it for - as the racing quad provides this information in FPV goggles so there's not much need for this (maybe except additional alarm on the Taranis). But that's a question for another forum, right...

Thanks!

I've read the linked articles - thank you for it. But still I'm unsure about correct wiring as the XSR receiver of course has separate S.Port and SBUS pins. But my Omnibus F4 V3 has only one SBUS pin - I assume this one is inverted. Where do I have to connect the S.Port to monitor the voltage of the main LiPo battery?

Sorry for noobish questions - but yes, I'm newbie in such a hobby and honestly it's hell to find out anything clearly described about the FC's pinouts, wiring etc... There are too many combinations and tiny changes from board to board...

Thanks.

On F4 controllers, the SBUS pin (if present) is dedicated and has hardware inversion done in hardware. You can't "uninvert" this, it's hardwired for the FrSky protocol and you can only connect the SBUS from the receiver here. The SmartPort can be wired to any free UART and you need to set it up accordingly in the ports page (UARTx - Telemetry output: SmartPort), as it's also an inversed protocol (boo FrSky, I guess).

Then, you need to take care of the SmartPort inversion. Either:
- pick the uninverted signal up from the receiver, as it's possible on some receivers: https://oscarliang.com/uninverted-sbus-s...receivers/
OR
- set up softserial inversion: https://oscarliang.com/betaflight-soft-s...-smartport
OR
- get a flight controller with Smartport inversion built in hardware (on a dedicated pin)

This is also a good resource: https://blog.dronetrest.com/omnibus-f4-f...ler-guide/

Also, in the same school of thought as above, here's how to get telemetry from the LED output