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Drone flight controller not seeing receiver after crash

#1
Hey guys, I recently crashed my drone and when it crashed the propeller snagged the wires leading to my receiver and they became exposed. I beleive that the sbus and 5 volt cables might have shorted, but do not know for sure. I soldiered the wires back together and plugged the battery in. I also used a multimeter to check that the wires which broke were not broken in the insulation. The flight controller turns on and works fine, and my Frsky rxsr receiver binds to my Frsky lite pro remote control, but the flight controller receives no input from the receiver. I even bought another receiver but that also did not work. I honestly have no clue what's wrong and would really appreciate any insight as i'm pretty new to all this.

(Added some images of the drone and it connecting to Betaflight)
 

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ElectriSean

Eternal Student
Mentor
#4
If you've replaced the Rx, and the wires are good, the only thing left is the FC. You may be able to use a different UART, depending on what FC you're using.
 
#5
If you've replaced the Rx, and the wires are good, the only thing left is the FC. You may be able to use a different UART, depending on what FC you're using.
Yeah i'm using a MAMBA F405 mini MK2 flight controller, which when plugged into Betaflight shows four UART ports. (2 of which are already being used) Here's a diagram of the board which came with my drone. I have never interacted with UART and don't really know what do with it. All I know is that it means that you can use different data cables. Should I simply switch my Sbus cable to a different UART pad on the flight controller or is there something I can do in Betaflight software wise.
 

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ElectriSean

Eternal Student
Mentor
#6
UART's are serial ports, with a Tx and Rx wire. Data only flows in one direction on each wire. SBUS is a serial protocol, but the problem with it is it's an inverted signal, and F4 chips can't uninvert a signal in software. So F4 based boards have an inverter built in and that pad is labeled SBUS. Some boards have 2 inverters (JBF4 for example) for smart port telemetry. The drawing says UART6 is used for telemetry, so it might work. If not, you'll have to "hack" your Rx or run CPPM if your Rx can do it. To try, connect the Rx signal wire to RX6, then in the ports tab disable SerialRx from its current port and enable it on UART6.
 
#7
UART's are serial ports, with a Tx and Rx wire. Data only flows in one direction on each wire. SBUS is a serial protocol, but the problem with it is it's an inverted signal, and F4 chips can't uninvert a signal in software. So F4 based boards have an inverter built in and that pad is labeled SBUS. Some boards have 2 inverters (JBF4 for example) for smart port telemetry. The drawing says UART6 is used for telemetry, so it might work. If not, you'll have to "hack" your Rx or run CPPM if your Rx can do it. To try, connect the Rx signal wire to RX6, then in the ports tab disable SerialRx from its current port and enable it on UART6.
I tried plugging it in to uart 6 so I think im just going to hack the rxsr. I looked it up and found out that if I soldier a wire onto those two pads shown below it will un invert the signal and when I put the wire on UART 6 it will work. Is this true?
 

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#8
Update: I got Betaflight to see my drone!!! The only problem now is that whenever I pass my throttle over the low threshold which I set to be 1000, the drone starts beeping like crazy. I Brough it outside and tried arming it but it just kept on beeping and eventually when I moved my throttle just a tiny bit it went full speed (nothing was damaged) Any insight about what could be causing this?
 

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