MINI REVIEW
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This is a great small FlySky receiver with telemetry and good range. 
You can connect with FPort or with SBus (inverted pad).
With stock antenna on radio, far away from city, @700m, RSSI was bouncing between 40 and 70.
RSSI 50 is low. And 40 critical. But with directional radio antenna, it easily handles 1.1km+
But, sometimes even with >70 RSSI , it failsafes. 


SETUP
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Easiest is to connect outer FPort pad to any TX. Make sure serialrx_halfduplex=on.


FIRMWARE UPDATE (Flight Controller)
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1) Make sure all 4 wires connected: Gnd, 4.5V, RX, TX
2) Hold button, and connect USB on FC. It has solid blue LED.
3) Connect BF.  Make sure radio is off and port is not enabled as Serial.
4) if its connected to UART6, in BF CLI: serialpassthrough 5 57600
5) After 10sec, you will see in CLI its firmware info. Disconnect BF.
6) Connect Crossover Tool. After scanning it will warn manual mode. Blue LED is off.
7) Select the firmware and update.


TROUBLESHOOTING
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Slow red LED flashing - normal, no radio signal or not bound
Solid red LED - bound and hears radio.
red+blue double flash every 5 sec = broken
solid blue = update mode.

There are 2 firmware update tools. Old white one (has firmware 2.0.2), and new black one ( has online test firmware 2.0.5).

You cannot connect to SBus on a normal RX pad on any F4 FC. You must use the special SBus pad.

2.0.5 firmware options
- SBus fast baud works if you enable SBus fast baud in Betaflight.
- FPort fast baud doesnt work on any FC I have
- I tried changing direction, but haven't figured out what it does.


UNBRICK
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I bricked one receiver 1+ year ago.
You must use CP2102 USB bridge. The 3.3V pin didnt work. I used the 5V pin.
I used Fiddler with good receiver, and download the 54_[1].mxo firmware in the response.
I then connected the bricked receiver to the CP2102, and held button to go into manual mode (solid blue LED).
I was then able to offline flash (confirm in the warning). It now works!


BRICK 3rd receiver.
=========
Unfortunately, I had a loose USB cable, and I managed to brick the 3rd receiver.
With 2.0.5 firmware, it has blue+red double flash every 5 sec. 
It reports correct firmware in serialpassthrough.
I flashed back to 2.0.2 and it looks like it works. Red led slow blink. 
I held button, fast red flashing indicating binding.
But, it fails to bind.

The newer firmware update tool looks like this:

Did you get rssi on opentx?

Good question..

Im super busy. And I just wasted HOURS fixing GHF411. I swapped MCU, and after putting 4" drone back together.. one motor not spinning right.