Rotorflight DSM(2)/DSMX Technical Integration Guide

Problems surrounding DSM vs DSMX Spektrum Satellite in Rotorflight

1. Resolving the "Missing Channels Beyond AUX1" Issue

When running older DSM2 or improperly bound DSMX receivers, channels past Channel 5 (Pitch/Aux1, Aux2, Aux3) often fail to register in Rotorflight's channel monitor. This is caused by protocol framing truncations.

Protocol Mode Resolution Max Channels Supported Frame Rate
SPEKTRUM1024 (DSM2) 1024-bit 5–6 Channels 22ms
SPEKTRUM2048 (DSMX) 2048-bit Up to 12 Channels 11ms / 22ms

Why Spektrum DSMX (2048) Fixes the Issue

A Spektrum DSMX (2048) satellite receiver provides the full 2048-bit payload required to transmit 7 to 12 channels down a single serial wire. Upgrading to or properly configuring DSMX mode restores full operation to Pitch (Aux1) and all auxiliary switches.

Fix Procedure 1: Binding via CLI for DSMX (2048)

  1. In Rotorflight Configurator, open the CLI tab.
  2. Force the satellite into 2048-bit / DSMX 10-pulse bind mode: 
    set spektrum_sat_bind = 9
set spektrum_sat_bind_autorst = 0
save
  3. Disconnect USB and power-cycle the flight controller. The satellite LED will flash rapidly.
  4. Turn on your Spektrum transmitter in Bind mode.
  5. Once bound (solid LED), reconnect to CLI and clear the bind flag: 
    set spektrum_sat_bind = 0
save
  6. In the Receiver Tab, change Serial Receiver Provider to SPEKTRUM2048.

Fix Procedure 2: Hardware Receiver Binding Method (Most Reliable)

If CLI binding defaults to DSM2 legacy mode, force full-frame DSMX binding using a physical receiver:

  1. Connect the satellite receiver to a standard Spektrum main receiver (e.g., AR6200 / AR8000) equipped with a remote port.
  2. Insert a bind plug into the main receiver and bind it to your transmitter.
  3. Verify all channels are active on the transmitter.
  4. Disconnect the satellite from the main receiver and wire it back to your FlyWing F405 flight controller. The satellite retains the multi-channel DSMX parameter profile permanently.

2. Long-Term Recommended Receiver Architecture

Legacy Spektrum satellite receivers lack native telemetry and are prone to framing limits on modern flight controllers. For optimal stability and access to Rotorflight's real-time PID tuning via transmitter Lua scripts, upgrade to a modern Spektrum SRXL2 receiver (e.g., SPM4650).