FrSky new arrival - Full range ultra mini redundancy receiver R-XSR! - Page 11 - RC Groups
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Oct 09, 2017, 04:29 PM
Registered User
Bill Glover's Avatar
Quote:
Originally Posted by mrmurder19.75
Tiny, weigh next to nothing, full range, telemetry and now compatible with lua script.
And cheap
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Oct 09, 2017, 06:37 PM
Registered User
Quote:
Originally Posted by Mosch
maybe you guys are interested - my uninverted mod of the R-XSR.
works for me at the bench. will try it tomorrow.

1. cut trace on the upper side
2. clean the PCB (remove paint) and pre-solder the small solder point (red arrow)
3. connect to pin 3

As mentioned, not tried in-flight yet! if you want to try it do it on your own risk

https://vimeo.com/237188519
I did this (with the newer version with the solder pad) and can confirm that it works. I tried this on a BFF3 board because my F4 board isn't working, but I turned telemetry inversion on (tlm_inverted = off is default in BF, per the S.Port standard) and the R-XSR was reporting telemtry.

I'd wager that the resistor that connects the trace could also be removed, and the (un)inverted S.Port signal soldered to it.

Quote:
Originally Posted by AndreaHuang
Hi, we uploaded the latest firmware today and this firmware adds the lua script to let you adjust the PID parameters for your FC. Here is the link: https://www.frsky-rc.com/r-xsr/



Hello, please find the picture here, and we add the 2 soldering points for real "inverted SBUS out" and "inverted S.Port" on the board. Please check the picture below.
Attachment 10417355
I believe what Andrea is saying is that the standard for S.Port and SBUS signal is "inverted" from the FC point of view, but from the standard point of view it isn't inverted, its the standard. The FC and the SBUS just weren't aligned at their inception. So to get an "(un)inverted SBUS" and "(un)inverted S.Port" you "invert" them from the standard, making them appear uninverted to the FC.

What the FC says is inverted and what the SBUS/S.Port standard says is inverted are opposite.

Hope that makes sense, but its basically two standards arguing which is right.
Oct 09, 2017, 08:10 PM
Registered User
As any engineer will tell you, the nice thing about standards is that there are so many of them........
Oct 09, 2017, 09:28 PM
FrSky-MKT
Quote:
Originally Posted by Sidewinder33
I did this (with the newer version with the solder pad) and can confirm that it works. I tried this on a BFF3 board because my F4 board isn't working, but I turned telemetry inversion on (tlm_inverted = off is default in BF, per the S.Port standard) and the R-XSR was reporting telemtry.

I'd wager that the resistor that connects the trace could also be removed, and the (un)inverted S.Port signal soldered to it.



I believe what Andrea is saying is that the standard for S.Port and SBUS signal is "inverted" from the FC point of view, but from the standard point of view it isn't inverted, its the standard. The FC and the SBUS just weren't aligned at their inception. So to get an "(un)inverted SBUS" and "(un)inverted S.Port" you "invert" them from the standard, making them appear uninverted to the FC.

What the FC says is inverted and what the SBUS/S.Port standard says is inverted are opposite.

Hope that makes sense, but its basically two standards arguing which is right.
Hello sir,

Thank you for trying to clarify these ports. Please let me clarify here again.
We should clarify that the protocol and the definition of the S.Port were defined previously as 2013 by FrSky for all our S.Port RX. So please be clear that the standard S.port and SBUS out ports are the misunderstood "inverted" ports you said.
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Thank you.
Last edited by AndreaHuang; Oct 10, 2017 at 09:52 AM.
Oct 10, 2017, 03:26 AM
Registered User
Sidewinder, did you just get the “uninverted” signal on the P pad? It looks like you scrapped the surface...is there more than just soldering to p pad?
Then it looks like you soldered the other end directly to the pin (I am assuming you first “desoldered the pin” or cut its source?
Oct 10, 2017, 04:40 AM
Registered User
A F4 needs uninverted TLM as long as you have a board which doesn’t have a HW inverter... The default of the r-xsr is inverted

The P pad seems to be uninverted. Used a brand new 2nd r-xsr and was able to do discover the sensors
Last edited by Mosch; Oct 10, 2017 at 12:18 PM.
Oct 10, 2017, 10:47 AM
Krotow
What? R-XSR have clearly distinguished pads of non-inverted signals? Love it. Someone with R-XSR and F4 FC board - please test them.

Quote:
Originally Posted by Mosch
A F4 needs uninverted TLM as long as you have a board which doesn’t have a HW inverter... The default of the r-xsr is inverted

Correct me if I’m wrong but the P pad is still the inverted signal, right? Confusing write up
SBUS concept (all channels transmitted as serial digital signal) came from Futaba where SBUS signal was inverted. Others started to use the same signal for their RX-es to be compatible with FC-s that initially was intended for Futaba RX-es. We still are affected by this legacy. So think opposite. Logically non-inverted digital signal (high signal level have high voltage and low level - zero or very low voltage) are inverted from Futaba SBUS perspective and vice versa. So all is good with R-XSR pads
Oct 10, 2017, 12:08 PM
Registered User
Many serial protocols over the years have used inverted logic. IMO the inversion should be provided on the FC boards.
Oct 10, 2017, 12:34 PM
Registered User
Tested. Updated my post

https://www.rcgroups.com/forums/show...&postcount=125
Oct 10, 2017, 12:55 PM
Registered User
Nice clean mod!
Oct 12, 2017, 12:14 AM
Registered User
Quote:
Originally Posted by Glasairsportsman
Sidewinder, did you just get the “uninverted” signal on the P pad? It looks like you scrapped the surface...is there more than just soldering to p pad?
Then it looks like you soldered the other end directly to the pin (I am assuming you first “desoldered the pin” or cut its source?
Glasairsportsman,

I did the mod that Mosch did, but instead of having to scratch the trace as was shown, the later versions of the receiver have exposed solder pads, so no scratching the board required ( the later versions) I cut the trace leading to the pin on the connector as Mosch did, and was able to solder the pad to the pin directly.

To avoid any more confusion over what's inverted and isn't. A uart without an inverter on it can receive and transmitter the telemetry information via the provided P pad. All you have to do flight controller side is turn tlm_inverted =off ( default) to on.
Oct 12, 2017, 05:00 PM
Registered User
Thanks!
Oct 12, 2017, 05:42 PM
Registered User
I am the market for a new quad, and quite interested in this new R-XSR. If I understand correctly, apart from a money point of view, there is not really so much more interest in going XM+?
Oct 12, 2017, 05:58 PM
Rotozuk's Avatar
It is smaller and has telemetry. What is not to like?
https://alofthobbies.com/frsky-r-xsr.html
Oct 13, 2017, 08:02 AM
Registered User
That's what I supposed, but as I'm a beginner I'm trying to confirm I understand everything before investing

Using it with an HGLRC F425, would there be any need and point to do the uninverted trick? What kind of telemetry data could I get with this stack?


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