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Oct 28, 2020, 11:41 PM
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Thread OP
Help!

FrSky D8 Mini Compatible Receiver SBUS


Hello!

Having trouble with this receiver.. here's some info with the hope someone far more knowledgeable might point me in the right direction..

Working on an older CrazyBeeF3 FC from my Mobula7, I recently had XM+ wired up and working with my XLite (not pro or s) - I've cut the end closest to the receiver and rewired to a smaller less capable D8 Mini FrSky "compatible" receiver to salvage the XM+ for another project..

Both of these mods are intended to improve the range over the SPI integrated FrSky receiver, and since the antenna has come off..

The module powers up and I'm able to bind (when I turn my receiver off, the blue LED flashes on the chip), but BetaFlight registers no inputs and shows Arming Disable Flags = RXFailsafe; What gives?

Initially I considered FrSky SBUS inversion to be suspect.. but having tried following along to accommodate this FPORT; RXHalfDuplex; RXInverted; only pad available is RX on FC), but seems to be a dead end unless I'm doing it wrong..

Beginning to realize, this is probably my older CrazybeeF3 doesn't support SBUS receiver? I've seen there are pads on FC's with dedicated SBUS pads.. but unclear to me if that is in fact a required pad for that exact purpose.. or if a UART capable pad is all I need. Is this just my F3 board isn't capable?

-Gnd>Gnd, VVC>v5, SBUS>RX, Initially that was all I'd done (result was the same as later.. binding succeeds, no input), then I realized I needed to short out the SBUS jump on the FrSky D8 Receiver.. even so, this did not fix my problem. I have not soldered any of the side channel terminals.
-As before with the XM+ the The Flight Controller configuration is set to Serial Based and SBUS, my Channel Map to TEAR1234
-Have tried AETR, Set SerialRX_Inverted=ON, Set SerialRX_halfduplex =ON, Changing the FC Config from SBUS>FPORT

The Mobula7 is my one and only current drone, I've done a few successful mods on it so far, but that is the extent to my experience.. be gentle! I'm a bit of a newb.. any insight or confirmation of my current assumption are welcome.

CrazyBeeF3 Flight controller info, identifier: BTFL, version: 4.0.6 - Released September 1 2019
FrSky D8 Mini Compatible Receiver
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Oct 29, 2020, 08:14 AM
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Ace12GA's Avatar
The XM+ is only SBUS. If it was working just fine, that's not your issue. The mini one has a bridge pad on the one side. By default it's running in PPM mode. You need to bridge the pads to enable SBUS.
Oct 29, 2020, 11:22 AM
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Thread OP
Quote:
Originally Posted by Ace12GA
The XM+ is only SBUS. If it was working just fine, that's not your issue. The mini one has a bridge pad on the one side. By default it's running in PPM mode. You need to bridge the pads to enable SBUS.
Thanks for helping out!
I mentioned this in my wall of text, I have bridged the SBUS pads, perhaps I’ve done that wrong? (Attached image)

It’s not possible I put the module into another mode unsigned the bind button is it?
Last edited by Tojolobal; Oct 29, 2020 at 11:41 AM.
Oct 29, 2020, 01:04 PM
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Ace12GA's Avatar
No, looks like the bridged the solder pads just fine. Your VCC and GND ones are a little more suspect (like to see nice shiny solder with smooth fillets onto the pads.).

I'm not sure why you're not seeing output. If you swap the XM+ back in, I presume it works fine?

On your radio, you've set the mode to D8?

I'm attaching two pics with the wiring broken out for anyone else that stumbles upon this. I found the product page seriously lacking for details on the pinout.
Oct 29, 2020, 06:07 PM
Registered User
Thread OP
Thanks again for the effort.

I am binding in D8 mode yes, I changed no other settings/channels etc on my radio though, just changed to D8 on the XLite rebound and it connected easily enough, had no issues with the XM+ aside from getting RSSI to show ( which I did get going )

Hmm .. Iíll take your advice and pit the XM+ back to test and back to this again if it works. I donít mind the criticism of my soldering.. I know I need to improve (picked up a practice board for that reason).. I figured with the power and binding working I should be good, but worth a try.



Quote:
Originally Posted by Ace12GA
No, looks like the bridged the solder pads just fine. Your VCC and GND ones are a little more suspect (like to see nice shiny solder with smooth fillets onto the pads.).

I'm not sure why you're not seeing output. If you swap the XM+ back in, I presume it works fine?

On your radio, you've set the mode to D8?

I'm attaching two pics with the wiring broken out for anyone else that stumbles upon this. I found the product page seriously lacking for details on the pinout.
Nov 14, 2020, 04:15 PM
Registered User
Thread OP

D8 receiver fixed.


Replying back to note my success. I did find the signal wire on the receiver ended up being lose.
Even though the IAO board was not touched, during the switch, when I moved back to the old receiver it wasn't working either.. re-soldered the signal wire and both receivers ended up working properly (XM+ and the new smaller D8 receiver I was trying to move over to)

Thanks for your help, Was trying to avoid touching the main board and didn't expect the signal wire to be a problem on that end (was hot glued to firmly secure it a while back).

Getting inputs now, flight tested successfully as well.
Thanks again for your suggestions


Quote:
Originally Posted by Ace12GA
No, looks like the bridged the solder pads just fine. Your VCC and GND ones are a little more suspect (like to see nice shiny solder with smooth fillets onto the pads.).

I'm not sure why you're not seeing output. If you swap the XM+ back in, I presume it works fine?

On your radio, you've set the mode to D8?

I'm attaching two pics with the wiring broken out for anyone else that stumbles upon this. I found the product page seriously lacking for details on the pinout.
Nov 16, 2020, 10:45 AM
Registered User
Ace12GA's Avatar
Glad you solved it. Happy flying.


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