Your SBUS input isn't useless anymore!

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---
00:00:00 - The problem we're solving today: F4 UART inversion
00:00:54 - Why this problem exists
00:06:41 - How we can get around the problem
00:11:16 - The fix is different on ELRS 3.3
00:13:07 - Have I earned your support yet?
2023 Freestyle FPV Drone Build For Total Beginners
• 2023 Freestyle FPV Dro...

[@JPspinFPV]

I enjoy the rants of a live stream, but these are the videos that brought me to your channel. Clear, concise explanations.

[@MasterApeFPV]

100% agree

[@thafactortwentyfour6866]

I totally disagree this guy will confuse the shit out of you

[@MasterApeFPV]

@@thafactortwentyfour6866how?! 😂 He literally goes through stuff step by step or tells you “watch this if you don’t know X”. I have trouble shot 90% of my problems and learned what I know about FPV through JBs videos.

[@thafactor24]

When I started flying fpv 2016 I did watch a lot of his videos but thru my fpv journey I've learned this guy does not keep shit simple he does shit a lot of time that's way more difficult than it really is so after he makes a video I will watch many more to come up with my on decisions on how shit really goes this guy takes the difficult route and trust me shit don't be that difficult he makes shit difficult sometimes

[@MasterApeFPV]

@@thafactor24 Ill give you that sometimes he goes into depth and does deep dives on topics. Like in this video. However, when JB does, he tells you straight away about it, or in any case there are chapters. You dont have to watch the full video that way. Otherwise I am not sure where he does stuff that is way more difficult..

[@KrotowX]

The chapter "Why the problem exists" lack the very reason about the inverted serial signal origin :) Who are interested - it is because when Futaba invented SBUS protocol more than decade ago, they found that inverted signal make receiver output signal path to destination (FC, servo etc.) less affected to electric noise. For electronics in those days logical zero as high voltage and logical 1 as low voltage made signal path a bit more reliable. Nowadays better electronics and shorter signal paths in smaller drones eliminated need for signal inversion and now RC circuits use direct signals without inversion.

[@JEFF-P-V]

Excited to see Bardwell pumping out content like this again. Keep it up, JB!

[@johnpaulgorman]

Man this is the first video that anyone (including yours) where this has been explained properly, linking the issue to the F4 chip and not the F4 FC boards. Well done sir in explaining and explaining the double inversion, such an easy concept when explained properly. I never got this concept pre-covid when I flew before and now that I understand it, nothing is left with SBus/FPort as I moved everythig to ELRS ;) However I have loads of F4 boards so this will be a neat trick. Now, if only you know a trick to repurpose an SPI receiver for something useful now that I added ELRS instead that would be smashing for micros ;)

[@flyingdutchmanfpv]

And this is why you're the fpvknowitall, great info

[@AndreFPV]

I have been using the ELRS SBUS output to install an ELRS received on an old NAZA-M v2 system that only supports SBUS. It works like a charm. Thanks JB for the good content.

[@richardamiss7000]

After half a decade in this hobby I learned something new today. Thanks JB!

[@calisti9308]

This is exactly why I’m a patron of yours.

[@ameyamusic]

You are like the User's Manual for all drone guys!

[@thafactortwentyfour6866]

Not me

[@ericschellenberger612]

I had this situation last week, got it sorted with help at intoFPV, and boom, here's your video explaining everything. LOL Yup, you do amazing work. Cheers!

[@hanspeterfranz6888]

Thank´s for this information!

[@MCsCreations]

Thanks a bunch for all the info, Joshua! 😊 Stay safe there with your family! 🖖😊

[@robertparenton7470]

Thank You!

[@PIDtoolbox]

Thanks for this!

[@lowriderfpv8440]

Thank You!😁

[@jordancraig5188]

Ty JB. I needed this for my emax f4 magnum stack. I learned something new today. Your the man.

[@Truth12345]

Great info, thx

[@powersv2]

This is the one. I have this limitation and thank you JB.

[@doratai7535]

Thank you! I can put black box on my F4 toothpick now!

[@anthony-friskettiphoto1008]

Another great video!

[@jmc_fpv]

That is really NICE Joshua! ❤

[@hobbyking.tamizh]

i just have a RM pocket cc2500 protocol with Sbus receiver. i was struggling to understand difference between Sbus and other protocols, whether i can connect my sbus to a non sbus port etc etc. this one video helped me through lot of questions. Thank u so much. Love from India 👍

[@73FPV]

great content. thanks JB

[@airdevil21]

Thank you Joshua!!! I didnt know this......Now i can use elrs on my older kwads my eachine wizard 220 X and the babyhawk r 3inch :)

[@henrirotthier5710]

This was great. Such good content 👍

[@123myfelix]

This video pushed me over the edge to donate and join your Patreon 😀 thank you for all you do in the community!

[@JoshuaBardwell]

Awesome! Thank you!

[@fuckinashol]

My favourite kind of video too!! And I don’t even use Elrs ! Thanks for all the education Joshua !

[@johnkurpiewski3996]

These are the best videos !

[@pgrcadventures1414]

I use the SBUS output feature from ELRS to fly my Goosky S1. The flight controller on it does not support crossfire protocol but supports Futaba SBUS which is popular in the heli community. Thanks to this feature I can now bring one remote to fly my kwads and helis!

[@chrisbee5481]

Will it work on the omp M1 too?

[@pgrcadventures1414]

Yes! It basically outputs the same sbus signal like a futaba receiver. Just configure the ELRS as JB shows and wire it up to the sbus port on the FBL.@@chrisbee5481

[@alfindo27]

Ilmu daging abangkuhhh , thanks 🔥🔥

[@Mamawsw]

Perfect Timing ! I have the same problem witch my aio and flyfish atlas 4. O3 and elrs and want to use gps so now I can with s bus ! I will try, thank you!

[@adityamaramis]

dudeeeee, I almost purchase f7 fc,. big thanks to u,. awsome

[@bastardjosh1354]

Dude lol! Great video thanks again! Just bought 2 of your shirts! And saw the patreon after I wrote this. Its coming next

[@nabecoat4960]

It's entirely possible this explains the issue I've been having with one of my quads. To the workbench!

[@ooOoo.....]

Brilliant!

[@spartan3299]

Thank you for mentioning Ardupilot. I have a F405 RadioLink FC that only has 2 telemetry ports and an SBUS input. Yes!

[@Jeff-tk2tn]

Hey man love your videos!

[@onnovannoort7690]

I have alot old f411fc's for inav use witch always gps in my case. Since i went digitale i dident use them, but now i can with Elrs, thats fantastic!

[@KangNdayAero]

Thats blown my mind !

[@peterboy209]

Bravo Bardwell 👍

[@winder6]

Awesome job thank you for doing this topic. There are some bind and fly airplanes that except s-bus and some gyros that offer safe launch wind mitigation. I also have some old fc for whoops that only have a s-bus pad. 😊

[@Catboy-hr2qp]

Well we know what bardwells wifi is called now 🤣.

[@OptiquevideoFPV]

Well thats sick 😮

[@modquad18]

Cool! Hope this works on the very earliest ELRS Rx’s from HM.

[@Compton05]

We need more like this Bro we miss it get Nerdy lol we like it 😂

[@keithcarpenter5254]

User defined receiver output protocol! That is brilliant. Open source ftw! 😊

[@alexanderfedorov7890]

can do it on crossfire since day 1. :)

[@ThE_SaM_22_]

Joshua for president🎉

[@notsure1502]

The last thing any guvmint wants is someone who will educate their constituants 😂

[@blackcollarfiend]

These are my favorite types of videos that you make. Any chance of getting a "JB's Deep Dives for Dorks" Playlist (if there isn't one already) that bundles all your more technical, firmware bending, pin re-mapping videos? Keep up the great work good sir.

[@centorx3]

the particular situation for me is my OMP M2 rc helicopter witch I want to wire up with a ELRS RX because I want to get rid of my old futaba T8J.I will test in the future with the help of this particular video thank you Josh :)

[@TheMetalSandman]

Joshua Bardwell.. you have definitely earned my subscribing to your Patreon :) It ain't much, but I owe it to you for all the FPV help. Maybe someday I could get to meet you in person, too! maybe.. that would be cool! Still need to work on those flips and tricks though :)

[@Switch180fpv]

Gold

[@chorchecze]

I have on my Mamba F405 connected ELRS Rx on S.Bus ant Tx1 and it works with CRSF protocol without issues. No need to use S.bus output from Rx.

[@JazzXP]

You can do this directly on many flight controllers too:- Look at the target parameters (there's a link when you go to flash) and you'll see resource INVERTER 1 C00 or similar, go to the CLI and type resource INVERTER 1 none and that'll free up another UART for use (I was using the Diatone Mamba F405 Mk2, and now have Crossfire on UART1 on the SBUS and TX1 pads).

[@JoshuaBardwell]

Unfortunately, many FC do not have a switchable inverter. You won't find an INVERTER resource on those FC. But it's a good idea, and definitely deserves to be included in this tutorial, especially for Crossfire users who can't ouptut inverted SBUS as far as I know.

[@maceliusfpv370]

This is great (tho seeminly easy to implement that it's kind of late that they thought of this, (considering how fully-featured even the later release candidate builds were), I can finally upgrade those couple whoops I've got kicking around.

[@johnsmithe4656]

How delightfully convoluted! And the double inversion does nothing to exacerbate latency issues?

[@JoshuaBardwell]

The latency coming out of the ELRS receiver is the same, since it is the thing generating the signal. The hardware inverter on the FC adds picoseconds of latency -- essentially none.

[@conorstewart2214]

The inverter will be a very simple device, potentially as simple as a single transistor and resistor, it will not add any noticeable latency only the time it takes for the transistor to switch which is negligible, most likely in the picosecond range.

[@JoshuaBardwell]

No, not at all. The latency of the hardware inverter is in the picoseconds range.

[@dronepilot260rc]

I’ve been running sbus for years now lol 😅 even on crsf

[@CarbonGlassMan]

That's pretty dang handy. I only have a couple F411 AIO boards left & the F411 only have 2 UARTs. I think all of my F405 FCs have at least 3. Maybe some of the older Mamba mk2 F405 FCs only have 2, I don't remember.

[@stevebarrow3042]

I think the MSH Brain 2 only uses non inverted sbus and this receiver seems perfect for that!

[@imik3y]

Mamba F405 stack works without inverting the signal on the sbus pad. You can send normal crossfire signal in

[@alfindo27]

really???

[@txkflier]

I just got into ExpressLRS a few days ago and thought I needed a Matek CRSF to SBUS converter board to use a Hobby Eagle gyro. However, I couldn't find any for sale and found that Matek has apparently quit making them. Now I know why. ExpressLRS and its developers are amazing.

[@RubyS.1]

The HE a3super4 and mini will take crsf now too which is pretty cool.

[@txkflier]

@@RubyS.1Yeah, I saw that a little while ago.

[@naveennishad]

Jb , you just saved my one old baby hawk 2 drone

[@valzzu]

i did this with an rly old quad with f1

[@kaygeebee1962]

Is it possible to throw Drone Camps under the SBUS? 😂

[@djsolstice8964]

This is great. I have one drone, it only has SBUS and DSMX inputs (GepRC Cygnet3). Will the DSM trick work with a DSMX? Update: I did it, I got ELRS working on the Cygnet3 FC. ELRS config was SBUS (non-inverted). The board has no additional DSM pin, just another 3.3v pin, not sure if that's it or not. Either way. It works. Thanks

[@8si8]

Does inverting the signal twice introduce any delay in the signal or is it so fast anyway that it is negligible?

[@dieterweik6858]

It's ironic that in an attempt to make it easy to wire up, they actually make it more complicated. Manufacturers (probably the Marketing departments) make this stuff more complicated by labeling the board's output pads with protocol names. If UART pads were simply labeled active-high or active-low, one would know to simply match the signal appropriately. If it doesn't match, invert it. Job done.

[@JoshuaBardwell]

iFlight does it right, IMO, by naming the pad nR1 or whatever, meaning "inverted R1".

[@peterklemenc6194]

Like ExpressLRS....soon.....CAN-bus for drones, it's the car tech drone controllers need eventually.

[@asuras1]

Hi! Really great video for a very common problem for those who don't get FPV stuff for free. The only burning question I have: I don't have a wifi capable ELRS receiver (I re-used an old frsky r9m reciever). Can I still configure that somehow (e.g. through Betaflight passthrough)? Thanks!

[@JoshuaBardwell]

No I don't think so.

[@n8zfpv]

can you do the same with crossfre? i don't see an option on the XF nano RX manual to use inverted signal. only SBUS an inverted.(SBUS, n.i. SBUS)

[@jean-philippestiee3527]

A very good thing in v3.3, this sbus output. Avoid usage of converter elrs/sbus for stabilizer like Eagle A3 super 4.

[@BooDevil65]

Best $2 you'll spend on your quads!

[@strohmaster8721]

Ran into a problem when doing this. (I built Josh's 5"build) When powered by battery the reciver light is solid green and doesn't connect to transmitter. Poking around the ELRS site it says it's "primarily caused by pull-down resistor on the RX pad to aid with SBUS line inversion." Anyone have a work around for this?

[@nolansullivan9196]

Is the mount you have with the GPS available for purchase anywhere? Or is there a place I can access the file to print my own?

[@JoshuaBardwell]

That mount is for the Flite Test EZ-ID. It's here: www.thingiverse.com/thing:4874074

[@pavel4021]

Hello from Siberia! Good kind of video a lot of things you help to realise.

[@leandrosly]

This would help me a lot but I'm using 900MHz Express LRS with FrSky R9mx receivers =( (I don't think it would be possible, right?)

[@itsgoofy3189]

Ineed help I just got the jumper t light v2 and I need help flashing it I open the configurator and set the release as 3.3.2 device category should be jumper 2.4GHz and the device should have 2400 tx but the only options are stuff that says 2.4GHz please I need help I might quit I don't want to I want to fly whoops

[@nickvledder]

What a coincidence… I spent a few hours last weekend opening up my DTS GT200 with F4 omnibus flightcontroller to check if I could wire my ELRS Receiver to it. It won’t be easy.

[@KcCake]

Interesting. I think sbus has more input delay than tx/rx iirc

[@JoshuaBardwell]

The SBUS protocol has more latency than the CRSF protocol, but the SBUS pad has no more delay. The latency of the inverter is picoseconds.

[@KcCake]

@@JoshuaBardwell ohh ok. Thank you for the clarification Jb!

[@Ksmeex]

Okay, as someone who is new to expresslrs.... I've got several speedybee F4 stacks (a couple of different Version designations). Since the documentation shows that uart6 is available, I should just be able to connect to that uart using crossfire as the protocol and not have to worry about inverting anything?

[@JoshuaBardwell]

Correct.

[@normcleod360]

You run into the opposite problem connecting Fr-Sky to an arduino. The reciever has a build in signal invertor. It's only possible if you Connect the receiver to your arduino behind the signal invertor because the S-BUS on Arduino needs an uninverted signal

[@nanomiterctech423]

You didn't show the port tab , since that was a subs pad connected to UART 1 then is it configurable in port tab ? Or is UART1 visible in ports tab or not ?

[@JoshuaBardwell]

You would configure UART 1 as usual for CRSF. The fact that the inverter is present doesn't matter.

[@sulphur_fpv]

I might be wrong but can't you just set "sbus inversion = off" in the betaflight cli to achieve the same thing? However the zohd copilot is one fc that i can think of that accepts sbus and pwm only and there is no way to change it so this would be super useful for that i would presume.

[@JoshuaBardwell]

I think the option you're referring to is "serialrx_inverted". That option doesn't make an F4 processor be able to receive an inverted-serial protocol like SBUS or FPORT. That option is used to tell the FC whether the incoming protocl is inverted or not. So in theory, if you had an uninverted-SBUS signal coming from some device, you could use that option to tell the FC, "hey, you're about to get an SBUS signal, but it's not inverted like you think it should be." Frankly, the name of the tlm_inverted and serialrx_inverted options is consuing and a little bit misleading.

[@plop386]

it was mostly made to revive old legacy FC :) liek switch them to elrs

[@IshamPadron]

I've got two aio lumineer f4 FC that just became more useful.

[@ArchonLicht]

What's the difference between using inverted crossfire and just using an SBUS here?

[@JoshuaBardwell]

Inverted Crossfire has lower latency.

[@thompaulson5152]

Hay y'all just figured out sbus to tx and rssi to rx works to, no more flysky for me elrs all day

[@gregorydahl]

There is a 2.4 ghz 2 watt radio signal booster from happy model to make flysky go a half mile . But then what about video

[@sigterm15]

great idea. I dont have free uart because i want to use GPS so i can find my drone by coordinates from radio. so i will use sbus. which does not transmit telemetry. uh! so i have to record DVR of every single flight. ...

[@MessFPV]

Depending on your FC you can maybe also use soft serial to create an additional UART, it will be limited to 9600 bauds but that can do the job for GPS (not compatible with CRSF/ELRS or HD video systems). But if you have an SBUS pad this is obviously the best thing to do.

[@dronevan]

This is possible since the beginning... few brunches made it possible. I use sbus elrs since 1.5years at least

[@alainassaf]

in theory, if betaflight developpers wanted to, could they create an inverted protocol (let's call it XSBUS) that can interpret what a frsky receiver is sending to the f405 through a normal UART ? I am not talking about softserial where the f405 has to do extra work and latency is induced.

[@JoshuaBardwell]

No, it's not possible. Interpreting the serial signal is built into the hardware of the STM32 chip. By the time betaflight sees it, it's already been interpreted into 1's and 0's.

[@KwongKan]

Sooooooooooooooo the example is on an F405, which usually has 5 or so UARTs? On F411, 2 UARTs are 2 UARTs, wouldn't trust soft serial on any of 3 (digital VTX, receiver, GPS). Not that I endorse budget friendly FC if all 3 is required but still. On another note, saw some very specific F7 FC with 3 pads in total for UARTs, which should be the the intended case........... Wait, F7 doesn't care if signal is inverted.

[@dudebro2288]

I have your setup wired this way with gps but for some reason I have to start the flight controller with the usb port to a power bank before plug in the battery? Otherwise the elrs receiver doesn’t bind correctly. It’ll say it’s bound but it isn’t.

[@GearBangerFPV]

I’m having the same problem. Are you using the DJI 3-in-1 cable connection for your vtx?

[@dudebro2288]

Yes

[@GearBangerFPV]

If I unplug my 3-in-1 cable I can bind too. I tried removing the yellow (sbus) wire from the 3-in-1 cable but that didn’t fix it. Maybe this won’t work with Dji?

[@dudebro2288]

@@GearBangerFPVya right now I’m just living with having to jump start it on a external usb battery power bank. Sorta a pain. I played around with trying to put the receiver on different soldering pads no luck.

[@GearBangerFPV]

A pin was bent inside my flight controller causing it to still be connected even though I had pulled the wire. Bent the pin over and all is well in the world again. You can take a small needle and lift up the black plastic clip holding the yellow wire in on both sides of the 3-in-1 cable or just cut it off. That should solve the conflict issue.

[@PopGheorghe]

Does this mean a new life for 411?

[@ChrisQuadFPV]

Turns out FrSky is not that complicated 😊

[@ProjectAlien724]

I learned in the first 58 seconds just buy a f7 lol

[@Solomonkein611]

SBUS is an inverted parallel RX2 pin, not which free port you will not get.

[@daemn42]

Shame this is an ELRS-only solution (might save some time if you put that in the title). Crossfire itself can output SBUS (and even non-inverted SBUS), but can't do CRSF protocol with inverted Tx output. For a hardware solution I see a $4 board on Aliexpress that is an SBUS inverter.

[@JoshuaBardwell]

FWIW, ELRS is in the thumbnail.

[@rocketman221projects]

The free hardware solution is to desolder the inverter and bypass it with a jumper wire. Don't try it if you aren't any good at SMD soldering though.

[@user-bv2kv8hx5d]

10:05 - somebody needs soldering practice :)

[@JoshuaBardwell]

Ok but those aren't my solder joints :-)

[@mtyler2469]

Isn't inverted SBUS just IBUS?

[@jfrowiess]

Inverted SBUS is SUBS

[@techstuff6829]

Not quite, no.

[@gregorydahl]

Instead of hi lo hi lo hi lo hi lo hilo it goes lo hi lo hi lo hi lo . The opposite

[@TweakRacer]

The original title... "FC not enough UARTs? ExpressLRS can connect to the SBUS input!"... was better and more to the point. "Your SBUS input isn't useless anymore!" baits non ELRS users to click.

[@BeardedHobbyGuy]

But it became more relevant to more applications than just a uart issue.

[@TweakRacer]

No. This video about saving a UART by using the SBUS pad is only useful for ELRS users. What other applications?

[@JoshuaBardwell]

The thumbnail says ELRS.

[@TweakRacer]

Fair enough. Though a lot of people consume KZbin on their phones, which would be difficult to read the text in a thumbnail.