3. Flight Controller Reference

3.1 Pilot_PX Board — Signal Availability

Several documentation errors and omissions have been identified in the Pilot_PX peripherals page. The table below reflects confirmed hardware reality:

Signal
Status
Source
Notes

SBUS OUT

Not available

Pilot_PX

SBUS OUT pin shown in peripheral diagram is incorrect - diagram has an error

SBUS IN

Not available

Pilot_PX

Only PPM peripheral is connected to the Pixhawk FMU on Pilot_PX

PPM IN

Available

SERIAL5 connector

Shared with the label 'PPM' on the adapter board

SBUS-Servo OUT (ArduPilot)

Available

SERIAL5 connector

Exposed pin - ArduPilot only; configure SERIALX_PROTOCOL=15 for other serial ports

FMU_DBG (JTAG)

Available

Pilot_PX board

Pinout in docs under Pilot_PX connectors - compatible standard Pixhawk JTAG tools

I2S Audio

Not available

Adapter Default

Not routed to any connector on the default adapter board


3.2 PWM Output Access

A recurring source of confusion is how many PWM outputs are accessible and from which port.

Source
Count
How to access

Cube MAIN outputs

7

PWM1 connector on Adapter Default

(JST GH to JR adapter)

Cube AUX outputs

Not on Adapter Default

Available on B2B connector - requires custom adapter board or DCS2.VTOL board

Secondary FMU PWM

4

FMU_SEC connector on Pilot board - for secondary FMU only, not routed to Cube

Orin GPIO (I2C expander)

2 (GPIO_EXP4/5)

GPIO connector on Adapter Default - 3.3 V, not PWM-capable

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Note:

The DCS2.VTOL board (see docs.airvolute.com/autopilots/dcs2/.vtol-board) combines adapter and PDB functionality and exposes the full set of MAIN and AUX PWM outputs. It supports up to 14S battery input and is optimised for VTOL airframes. A new Adapter Default revision adding AUX support is also in development.


3.3 Serial / UART Port Reference

The following ports are physically accessible on the DCS2 Adapter Default board and can be configured in ArduPilot as telemetry, GPS, RCIN, or SBUS-Servo out:

Connector
ArduPilot Serial
Default use
Notes

SERIAL1

SERIAL1

Telemetry 1

Routed to Jetson — primary MAVLink endpoint

SERIAL5

SERIAL5

Telemetry 5 / SBUS

Contains UART + SBUS_OUT pin; SBUS-Servo out is ArduPilot-only

GPS1

SERIAL3

GPS

Standard JST GH GPS connector

GPS2

SERIAL4

GPS 2 / telemetry

Can be repurposed for telemetry if GPS2 is unused

ttyTHS0

-

Jetson↔Cube UART

Physical UART for mavlink-router; also accessible as ttyACM0 via USB

For PX4 / NuttX: consult the PX4 serial-port mapping for your specific FMU hardware version (e.g. CUAV Pixhawk V6X) at docs.px4.io to correlate SERIAL numbers with /dev/ttyS* device nodes.


3.4 Secondary (Onboard) FMU

Every DCS2 production board (green boards) contains an onboard secondary FMU in addition to the Cube autopilot socket.

Property
Detail

IMU

BMI088

Barometer

BMP390

Default firmware

ArduPilot 4.5.0 with Airvolute bootloader

USB access

Shared with Cube — switch via fmu_cube_usb_switch.py fmu

Serial access

SERIAL1 and SERIAL2 on the FMU_SEC connector

Typical use

Flies standalone on FPV-class Patron drones (no Cube); on Stribog drones it is present but idle

Pre-production boards

Blue boards — secondary FMU is empty (no firmware)

To switch the shared USB bus between Cube and secondary FMU:

To flash firmware to the secondary FMU, connect via a GCS after switching USB, or use the ArduPilot bootloader uploader directly from Jetson:


3.5 ARKV6X Flight Controller Setup

Users integrating the ARK Electronics FMUV6X in place of the Cube should follow this sequence:

  1. Flash the DCS2 using dcs-deploy as normal

  2. Install mavlink-router

  3. Build PX4 for ARKV6X default config and upload:

  1. Configure mavlink-router with the ARKV6X endpoint (note: 115200 baud, not 921600):

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