Hey guys,

just before I start digging deeper in my quad's body, first I'll try to ask here. First of all I must say I'm totally new in quads so I apologize for such a newbie questions and terminology.

I have the Eachine X220S (please note the S at the end - the newer version). This one should be equipped with Omnibus F4 V3 and has the Flysky FS-A8S. The RC is Flysky FS-I6.

When I was looking for solution when after about 5 flights the quad always tended to flip to the side when trying to get in the air, one of the things I've tried was to load default settings in Betaflight. So that's how I managed to find out this is not getting back to factory default settings  According to some video on YT I've managed to set up everything back to working state in Betaflight. BTW the problem was caused by loosen motors bolts so I decided to use Loctite threadlock, we shall see if it works.

I'm considering flashing unofficial firmware to my Flysky FS-I6 to get more than 6 channels. 8 would be enough for me. Currently there is S-BUS set up and everything works. One of my friends told me he would definitely recommend to use I-BUS instead as he says using S-BUS can cause Failsafe to work incorrectly. Is it true?

When I try to switch to I-BUS in Betaflight, I get no response from my RC at all (I've also tried all the UART options). Well the problem is I have no idea how the RX and FC are physically connected.

So before I start disassembling the frame, I'd like to ask following questions:

1. Shall I use S-BUS or I-BUS, which one is better and why? Are there any Failsafe problems with S-BUS?
   
2. If you recommend using I-BUS, what pin should the I-BUS/S.BUS output from the RX be connected to on the Omnibus F4 FC?
   

Any help will be appreciated, thanks.

1. IBUS is a tiny bit faster, SBUS on a Flysky radio doesn't give you any additional features so I would go with IBUS if possible. On the other hand - if changing it is problematic, I'd say just ignore it and go flying.

2. If you decide to change to IBUS, any not inverted RX pin should work.

BTW I'm a little bit confused here - as far as I know, FS-I6 is not really able to use S-BUS, only I-BUS, I wanted to ask if your TX is not an i6x, but I see you are talking about flashing firmware to it and that is only possible on the i6. Which Transmitter do you have - i6 or i6x?

As far as I know the failsafe problems with the FS-A8S receiver were limited to the Version 1, so unless you have very old stock, the failsafe problem should be sorted on SBUS. One of the other problems reported was that the V1 would revert from iBus to SBUS every time power was connected. I continued to have what I thought were brownout problems with my V2 A8S, but this may have been due to something else, regardless, the A8S is not as good as I 1st thought. Maybe ordering an X6B would be a good option for you, as long as there is space, it has 30.5mm mountings to fit in the stack.

I think you may have to download the FW to get iBus on the FS-I6, just to confirm this isn't the FS-I6X or the FS-I6S is it?

If I remember rightly you have to hold the button on the RX for 1 sec to change between SBUS and iBus, remember to go into RX settings in the transmitter and scroll down to set the correct 'output mode', if the menu is the same as the FS-I6X select PPM and iBus.

Edit to add : Just as I hit post I realized I forgot to mention iBus has a few Ms less latency, just like Konrad!!!

Thank you very much guys for your replies. I'm definitely sure it is the Flysky FS-I6 and NOT the FS-I6X, which provides 10ch as factory default. Unfortunately I don't have any of my quad gear here, so I'll take a look at home to check the RX version as well. So I'll open the frame as well to check the physical connection from RX to FC. I'll update this thread later on. Thank you very much so far!

(15-Mar-2018, 10:35 PM)KonradS Wrote: I'm a little bit confused here - as far as I know, FS-I6 is not really able to use S-BUS, only I-BUS, I wanted to ask if your TX is not an i6x, but I see you are talking about flashing firmware to it and that is only possible on the i6. Which Transmitter do you have - i6 or i6x?

I'm very sorry, my bad. I was pretty confident I have the FS-I6 as it should come as default with the X220S. But now I've checked that out just to ensure and found out they gave me the FS-I6X! Which should provide 10ch as it is from factory. But I wasn't able to get working more than 6 channels in Betaflight. The FS-A8S receiver should support 8ch. I'll have to check it out why it's not working.

(15-Mar-2018, 10:57 PM)Tom BD Bad Wrote: As far as I know the failsafe problems with the FS-A8S receiver were limited to the Version 1, so unless you have very old stock, the failsafe problem should be sorted on SBUS.

I've checked that out and it is V2 so it should be OK I guess?

(15-Mar-2018, 10:57 PM)Tom BD Bad Wrote: Maybe ordering an X6B would be a good option for you, as long as there is space, it has 30.5mm mountings to fit in the stack.

I'll consider replacing the RX for another one. I'm also considering replacing the Flysky RC for some Taranis, so I think I'll keep this one as long as I stay with Flysky...

Now back to IBUS - here's how the RX is currently connected to the FC:

   

WHITE wire is the one from IBUS/SBUS output of the Flysky FS-A8S RX. Is it the correct position even for IBUS for the Omnibus F4 V3 FC? If it is, the only thing I have to do is to switch it on the RX? And of course mess up with some of the Betaflight settings (UART)?

Thanks.

If you are using IBUS, then you can't connect the signal to SBUS pin on the FC. You will want to connect the IBUS from receiver to the RX1 on the FC.
Select serial based RX, IBUS and select serial rx for the UART1.

Ok, so according to the pinout I've found out so far the white wire from the RX should be resoldered to the pin I've marked with red circle on this picture - is this correct?

   

Correct. (I have to use at least 5 words for a post)

The 5V and ground is also near there, if you want cleaner wiring, you can also move the red and black wire.

Yeah, good point... Thanks!

   

Here's my RC setting (Flysky FS-I6X) - also tried switching PWM to PPM:

   

There is also this kind of setting, not sure what it means... Haven't tried to switch this one yet.

   

Any ideas on what could be wrong?

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BTW strange is that the RC was set up as on the picture - PWM + IBUS, but in Betaflight my quad was set up to SERIAL/SBUS. But everything worked...

In your ports tab you have UART 1 enabled under MSP. You need to have enabled under serial rx (1 to the right)

Disable the MSP on UART 1. Then try again.
You also have 3.1 firmware, I think you need 3.2 to work with newer configurator.

Thank you guys, finally I got everything working out. I've upgraded to latest Betaflight Configurator, set up everything again and everything seems to work now.

Still I'm considering resoldering the FPV parts (VTX + camera) as these are being powered from the FC and PDB board at this time. To be honest I haven't had time to do a proper test about the noise with my goggles (Eachine VR D2), but everytime I read about this everyone recommends leading power to FPV components directly from the battery. And now the frame is opened so I can do this quite easily... Hopefully... 

Thanks again, IBUS is working. BTW I didn't have had to do much less end point adjustments to get the right stick values in BF than before with SBUS, IBUS seems to be much more precise in this. Or maybe it's just by accident but still it's like that... 

Thank you all again for assistance and advices. Now I'm thiking of some more other things which I'll be writing in another thread later on.