I’m writing this just as a record since I struggled a lot to bind my Eachine i6 transmitter to the receiver included in the Eachine EX100 (iRangeX FS-RX). The main problem was that the receiver communicates with the flight controller through PPM (UART3 port in FC) and the i6 doesn’t support PPM with the standard firmware.
What I had to do was upload the FlySky i6 firmware to the transmitter, setup PPM, and bind to the receiver.
To upload new firmware go here and download entire repo as zip.
Then, using USB-UART converter, hook up the transmitter using this pinout:
From the download, open: FlySky-i6-Mod–master\Firmwares\Flysky i6 Original Firmware\FS-i6-Original -Firmware.exe
Open port, program.
That’s it, new firmware should be loaded.
To set-up transmitter, Turn ON, Hold OK button to enter menu, scroll down to RX Setup, OK, select AFHDS, OK, select OFF, long press Cancel to save. Turn off transmitter.
Now, connect BIND pin in receiver to ground and power it up, LED should start blinking.
Then, while holding BIND button in transmitter, turn it on. After a moment, LED in receiver should stop blinking and stay on. On transmitter, long press CANCEL. Then turn off transmitter. Then turn off receiver and remove BIND-GND pin connection.
TX/RX should be bonded now.