No RC signal (RC not found) with FlySky FS-iA6B on Pixhawk-clone board via PPM/RCIN

General
1

Hi all,

I’m trying to get RC input working and keep getting a “PreArm: RC not found”
error in QGroundControl, even though everything appears correctly connected.

Setup:

  • Flight controller: [insert exact board name/text printed on it here]
  • Firmware: ArduCopter 4.7.0
  • Frame: Quad X
  • Receiver: FlySky FS-iA6B (2.4GHz 6-channel)
  • Connection: Receiver’s PPM/CH1 pin → FC’s RCIN pin (3-pin cable, signal/+5V/GND)

What I’ve checked/tried:

  • Receiver LED is solid (bound), lights up when powered only through RCIN connection
  • RC_PROTOCOLS parameter = 1 (all protocols enabled)
  • Radio calibration screen in QGC shows no channel movement
  • Checked MAVLink Inspector → RC_CHANNELS message — values do not change
    when moving transmitter sticks
  • Verified wiring/pin connections look physically correct and secure
  • Tried power cycling in correct order (transmitter on first, then FC)

Signal does not seem to be reaching the flight controller at all. Has anyone
run into this specific combination (FS-iA6B + this board) or know if this
board’s RCIN pin might be mislabeled/wired differently than standard Pixhawk
pinouts?

Attaching a photo of my board and wiring for reference. Any help figuring
out what I’m missing would be greatly appreciated!

image
image1920×2560 718 KB

2

Use search on the forum for “FlySky FS-iA6B SBUS” and make that connection. Configure Sbus protocol on the Transmitter.

3

The wiring is wrong

The SENS port is for sensors for ibus telemetry from the fc (needs to be activated by the custom firmware server for this board) and you should see the wiki.

Plug it in the channel 1 connector and ensure ppm is enabled via the menu
If you the i6 and not the i6x sbus won’t work because the i6 cannot do sbus without firmware upgrade. It you got the i6x move the connector to the servo connectors besides the sens pin for sbus and enable it in the menu

On the pixhawk side wiring is correct