Need Help With a GHF411 Pro BMI 40A Flight Controller

[rabunnative]

So... I bought a GHF411 Pro BMI 40A flight controller, and I am having trouble connecting it to my transmitter. Just a couple of things to note before I get into all of the specific items that I am trying to connect: 1. The flight controller seems to work well. I can link to the board through betaflight and everything looks good. I am even able to change settings and save various parameters. 2. My transmitter and receiver are connecting normally. 3. My issue seems to be located between my receiver and the flight controller. I haven't had any luck getting them to communicate.

I am using the following components:
GHF411 Pro BMI 40A flight controller
Taranis X9D Plus transmitter (2.4 GHz ACCST)
FrSky X8R Receiver

I am attempting to use the SBUS port on the X8R Receiver to communicate with the flight controller. I have my cable soldered to the board in the configuration shown for SBUS on the Flitetest website.

Does anyone have any pointers that might be able to help me?

 

[LitterBug]

Screenshots of your ports tab and RX tab would be helpful as well as a picture of the RX soldered to the FC. It could be a wiring or settings issue.

Cheers!
LitterBug

 

[rabunnative]

Here are some pictures of our setup and the schematic we are going by.

 

[rabunnative]

Here are some other details that might be useful in determining our issue.

The transmitter is a Taranis X9D Plus running Open TX with firmware version 2.3.15
Our Flight Controller is the GHF411 Pro BMI 40A. In Betaflight, the firmware info for the board says MSP API: 1.46.0
The Betaflight App Version is 2025.12.2 and the firmware version is 4.5.2 BTFL

 

[rabunnative]

I may have just made a discovery. Let me know if anyone can confirm that this is correct.

I currently have the receiver soldered to the board in the configuration shown in the schematic above. The schematic shows SBUS Receiver (FrSky) soldered to the GND, 4.5V, and SBUS pad on the flight controller. Also on the schematic, there is a small window at the top of the picture that says, "When using an SBUS receiver, turn on port UART2 as serial Rx." and it shows a small screenshot from Betaflight. I researched how to connect a device to the flight controller using UART2, and Google says to solder and Rx device to the Tx2 tab on the flight controller.

The logic part of my brain says that I should probably solder to the Rx2 tab, but either way if this information is correct, I'm soldered to the wrong tab. It would be awesome if my problem is this simple. Can anyone confirm this is the issue? Thanks in advance.

 

[rabunnative]

Update: I tried soldering my Rx signal wire to the RX2 and then the TX2 pads shown in the schematic above. I still can't get any signal from my transmitter to the flight control board. I'm really hitting a dead end with this.

 

[Mr NCT]

Wish I knew something about this, sorry.

 

[FlyerInStyle]

Update: I tried soldering my Rx signal wire to the RX2 and then the TX2 pads shown in the schematic above. I still can't get any signal from my transmitter to the flight control board. I'm really hitting a dead end with this.

have you tried with a different receiver/ tried turning sbus inverting on? Sorry if I missed it, but is this Inav? Betaflight?

 

[rabunnative]

have you tried with a different receiver/ tried turning sbus inverting on? Sorry if I missed it, but is this Inav? Betaflight?

Betaflight. We originally tried to connect to an FrSky Archer Plus RS receiver. No luck. I had never used the Archer receiver with the Taranis transmitter before, so I decided to go with something I had success with before. I have used the X8R receivers on several projects and never had an issue. I feel like I'm all out of ideas. I just tried to flash the flight controller with new firmware. Everything looked like it was going well, but when I click the flash firmware button in betaflight, an error message pops up saying that there is no target. I keep hittin a dead end no matter where I turn.

 

[FlyerInStyle]

Betaflight. We originally tried to connect to an FrSky Archer Plus RS receiver. No luck. I had never used the Archer receiver with the Taranis transmitter before, so I decided to go with something I had success with before. I have used the X8R receivers on several projects and never had an issue. I feel like I'm all out of ideas. I just tried to flash the flight controller with new firmware. Everything looked like it was going well, but when I click the flash firmware button in betaflight, an error message pops up saying that there is no target. I keep hittin a dead end no matter where I turn.

is it in dfu mode when you falsh? check your device manager. If that doesn't work disconnect everything. Try again. For SBUS, do you happen to have a ppm receiver to connect to just check that the FC works, or another way to check the SBUS on the FC? I keep a pwm to sbus converter around for that reason.

 

[LitterBug]

So here's the deal with SBUS. It has an inverted signal which on a F4xx flight controller requires an inverter for the flight controller to decode it. Do NOT use just any serial port. You need the one that the manufacturer explicitly set up for SBUS. So use the picture above of an SBUS RX being hooked to the board. No other way will work. What you had originally was correct. Once you get that back, please take a picture of your serial ports tab and RX port tab. There are settings there that can also make/break the connection.

LitterBug

 

[LitterBug]

FYI, F3xx and F7xx processors can do inversion on any serial port, but you have to enable inversion on the port. Some F4xx based boards have a way to enable the inversion on a single RX port similar to F3 and F7, but in your case, they broke it out as a seperate pad for SBUS.

 

[rabunnative]

Just to confirm that I understand you correctly;

First, solder the signal wire back on the SBUS tab of the flight controller.
Second, install an SBUS inverter between the flight controller and the receiver
Third, ensure that the wire is connected to the SBUS port of the X8R receiver as shown in the picture below.

If this is correct, I will purchase an SBUS inverter. I will search for one, but if you have any suggestions about where to purchase one, let me know. Thanks for your help!

 

[LitterBug]

No inverter needed. The manufacturer has one on the SBUS pad. That is why you must connect it there. Just hook it back on that pad and send pictures of your ports tab and receiver tab.

 

[rabunnative]

OK. The receiver signal wire is connected to the SBUS pad on the flight controller again. Here are pictures of the Ports and Receiver Tabs in betaflight with the board connected.

On the receiver tab, I was under the impression that I should select "Serial (via UART) and then select SBUS from the dropdown tab below. Unfortunately, everything in the dropdown menu is grayed out, so we can't select anything. Thanks for your help.

 

[LitterBug]

Yes, SBUS needs to be selected on the Receiver tab. Without it, The FC has no idea what protocol to decode.

Looks like you may have an incomplete version of BetaFlight installed.

I may have one of those FCs here that I could test with. Think it has INAV on it now.

 

[LitterBug]

That looks like an older version of betaflight. The latest uses a web based configurator. I did find my board and flashed the latest version (2025.12.2) which works correctly. I am using ELRS which is CRSF. Once I selected the correct protocol, it works fine.

 

[rabunnative]

I wanted to give a final update here. We finally got the flight controller to work! As I walked through each suggestion here, I still could not get anything to work. When I was to the point of almost giving up hope, I had someone plug the controller into his Chromebook and everything worked. I don't know if the issue has anything to do with my computer running Windows 11 Pro, but we were using the same version of Betaflight on both computers and following the same procedures with the same USB cable. Anyway, thank you all for the guidance that you provided. It did help to push us in the right direction, and in some cases, it helped confirm that we were not crazy. Thanks again. I hope that this thread helps someone else in the future.

 

[Mr NCT]

I wanted to give a final update here. We finally got the flight controller to work! As I walked through each suggestion here, I still could not get anything to work. When I was to the point of almost giving up hope, I had someone plug the controller into his Chromebook and everything worked. I don't know if the issue has anything to do with my computer running Windows 11 Pro, but we were using the same version of Betaflight on both computers and following the same procedures with the same USB cable. Anyway, thank you all for the guidance that you provided. It did help to push us in the right direction, and in some cases, it helped confirm that we were not crazy. Thanks again. I hope that this thread helps someone else in the future.

That kind of information helps everybody, THANKS!!

 

[tomlogan1]

Had a similar issue with a SpeedyBee F405 Wing controller. Flashed (with Windows 11) completed perfectly but would not connect. Added each and every driver known to man and still no connection. Flashed again 4 or 5 times. Each time INAV said successful flash. Put it in the parts drawer and called it a day. Flashed again the next morning with LInux (different computer) and it works just fine.