PX4 User Guide
  • Introduction
  • Getting Started
    • Basic Concepts
    • Vehicles/Frames
    • Flight Controllers
    • Sensors
    • Radio Systems
    • Flight Modes
    • Vehicle Status Notifications
      • LED Meanings
      • Tune/Sound Meanings
      • Preflight Checks
    • Payloads & Cameras
    • Flight Reporting
  • Basic Assembly
    • Mounting the Flight Controller
    • Mounting the GPS/Compass
    • Vibration Isolation
    • Cable Wiring
    • CUAV Pixhawk V6X Wiring QuickStart
    • CUAV V5+ Wiring Quickstart
    • CUAV V5 nano Wiring Quickstart
    • Holybro Pixhawk 6C Wiring Quickstart
    • Holybro Pixhawk 6X Wiring Quickstart
    • Holybro Pixhawk 5X Wiring Quickstart
    • Holybro Pixhawk 4 Wiring Quickstart - Discontinued
    • Holybro Pixhawk 4 Mini Wiring Quickstart - Discontinued
    • Holybro Durandal Wiring Quickstart
    • Holybro Pix32 v5 Wiring Quickstart
    • Cube Wiring Quickstart
    • Pixracer Wiring Quickstart
    • mRo (3DR) Pixhawk Wiring Quickstart
  • Standard Configuration
    • Firmware
    • Airframe
    • Sensor Orientation
    • Compass
    • Gyroscope
    • Accelerometer
    • Airspeed
    • Level Horizon Calibration
    • Radio Setup
    • Joystick Setup
    • Flight Modes
    • Battery
    • Safety
      • Failsafe Simulation
    • ESC Calibration
    • Actuators
    • Autotune
  • Vehicle Types & Setup
    • Multicopters
      • Multicopter Config/Tuning
        • MC Filter/Control Latency Tuning
        • MC PID Tuning (Manual/Basic)
        • MC PID Tuning Guide (Manual/Advanced)
        • MC Setpoint Tuning (Trajectory Generator)
          • MC Jerk-limited Type Trajectory
        • Multicopter Racer Setup
      • X500 v2 (Pixhawk 6C)
      • X500 v2 (Pixhawk 5X)
      • X500 (Pixhawk 4)
      • S500 V2 (Pixhawk 4)
      • DJI F450 (CUAV v5+)
      • DJI F450 (CUAV v5 nano)
      • QAV250 (Pixhawk4 Mini) - Discontinued
      • DJI F450 + RTK (Pixhawk 3 Pro)
      • QAV250 (Pixhawk Mini)
      • QAV-R 5" Racer (Pixracer)
      • Omnicopter
    • Planes
      • Fixed Wing Config/Tuning
        • Fixedwing PID Tuning Guide
        • Fixedwing Advanced Tuning Guide
        • Fixedwing Trimming Guide
      • Reptile Dragon 2 (ARK6X)
      • Turbo Timber Evolution (Pixhawk 4 Mini)
      • Wing Wing Z84 (Pixracer)
    • VTOL
      • VTOL Config/Tuning
        • QuadPlane Configuration
        • Back-transition Tuning
        • VTOL w/o Airspeed Sensor
        • VTOL Weather Vane
      • Standard VTOL
        • FunCub QuadPlane (Pixhawk)
        • Ranger QuadPlane (Pixhawk)
        • Falcon Vertigo QuadPlane (Dropix)
      • Tailsitter VTOL
        • Build: TBS Caipiroshka Tailsitter Build (Pixracer)
      • Tiltrotor VTOL
        • Build: Convergence Tiltrotor (Pixfalcon)
    • Airships (experimental)
    • Autogyros (experimental)
      • ThunderFly Auto-G2 (Holybro pix32)
    • Balloons (experimental)
    • Helicopter (experimental)
      • Helicopter Config/Tuning
    • Rovers (experimental)
      • Traxxas Stampede
    • Submarines (experimental)
      • BlueROV2
    • Airframes Reference
  • Flying
    • First Flight Guidelines
    • Flying 101
    • Missions
      • Package Delivery Mission
    • GeoFence
    • Safety Point Planning
    • Flight Modes
      • Position Mode (MC)
      • Altitude Mode (MC)
      • Manual/Stabilized Mode (MC)
      • Acro Mode (MC)
      • Orbit Mode (MC)
      • Position Mode (FW)
      • Altitude Mode (FW)
      • Stabilized Mode (FW)
      • Acro Mode (FW)
      • Manual Mode (FW)
      • Takeoff Mode
      • Land Mode
      • Return Mode
      • Hold Mode
      • Mission Mode
      • Follow Me Mode
      • Offboard Mode
    • Terrain Following/Holding
  • Flight Log Analysis
    • Log Analysis using Flight Review
    • Log Analysis using PlotJuggler
  • Advanced Configuration
    • Finding/Updating Parameters
    • Full Parameter Reference
    • ECL/EKF Overview & Tuning
    • Flight Termination Configuration
    • Bootloader Flashing onto Betaflight Systems
    • Land Detector Configuration
    • Prearm/Arm/Disarm Configuration
    • IMU Factory Calibration
    • Sensor Thermal Compensation
    • Compass Power Compensation
    • Advanced Controller Orientation
    • Static Pressure Buildup
    • Serial Port Configuration
    • MAVLink Telemetry (OSD/GCS)
    • PX4 Ethernet Setup
    • Bootloader Update
  • Hardware (Drones&Parts)
    • Complete Vehicles
      • ModalAI Starling
      • PX4 Vision Kit
      • MindRacer BNF & RTF
        • MindRacer 210
        • NanoMind 110
      • Holybro Kopis 2
      • Bitcraze Crazyflie 2.1
    • Flight Controllers (Autopilots)
      • Pixhawk Series
        • Silicon Errata
      • Pixhawk Standard Autopilots
        • CUAV Pixhawk V6X (FMUv6X)
        • Holybro Pixhawk 6X (FMUv6X)
        • Holybro Pixhawk 6C (FMUv6C)
        • Holybro Pixhawk 6C Mini(FMUv6C)
        • Holybro Pix32 v6 (FMUv6C)
        • Holybro Pixhawk 5X (FMUv5X)
        • Holybro Pixhawk 4 (FMUv5) - Discontinued
        • Holybro Pixhawk 4 Mini (FMUv5) - Discontinued
        • Drotek Pixhawk 3 Pro (FMUv4pro)
        • mRo Pixracer (FMUv4)
        • Hex Cube Black (FMUv3)
        • mRo Pixhawk (FMUv3)
        • Holybro Pixhawk Mini (FMUv3) - Discontinued
      • Manufacturer-Supported Autopilots
        • AirMind MindPX
        • AirMind MindRacer
        • ARK Electronics ARKV6X
        • CUAV X7
        • CUAV Nora
        • CUAV V5+ (FMUv5)
        • CUAV V5 nano (FMUv5)
        • CUAV Pixhack v3 (FMUv3)
        • CubePilot Cube Orange+ (CubePilot)
        • CubePilot Cube Orange (CubePilot)
        • CubePilot Cube Yellow (CubePilot)
        • Holybro Kakute H7v2
        • Holybro Kakute H7mini
        • Holybro Kakute H7
        • Holybro Durandal
        • Holybro Pix32 v5
        • ModalAI Flight Core v1
        • ModalAI VOXL Flight
        • ModalAI VOXL 2
        • mRobotics-X2.1 (FMUv2)
        • mRo Control Zero F7)
        • NXP RDDRONE-FMUK66 FMU
        • Sky-Drones AIRLink
        • SPRacing SPRacingH7EXTREME
        • ThePeach FCC-K1
        • ThePeach FCC-R1
      • Experimental Autopilots
        • BeagleBone Blue
        • Raspberry Pi 2/3 Navio2
        • Raspberry Pi 2/3/4 PilotPi
          • PilotPi with Raspberry Pi OS
          • PilotPi with Ubuntu Server
      • Discontinued Autopilots/Vehicles
        • Drotek Dropix (FMUv2)
        • Omnibus F4 SD
        • BetaFPV Beta75X 2S Brushless Whoop
        • Bitcraze Crazyflie 2.0
        • Aerotenna OcPoC-Zynq Mini
        • CUAV v5
        • Holybro Kakute F7 (Discontinued)
        • Holybro Pixfalcon
        • Holybro pix32 (FMUv2)
        • mRo AUAV-X2
        • 3DR Pixhawk 1
        • Snapdragon Flight
        • Intel® Aero RTF Drone (Discontinued)
      • Pixhawk Autopilot Bus (PAB) & Carriers
        • ARK Electronics Pixhawk Autopilot Bus Carrier
    • Flight Controller Peripherals
      • ADSB/FLARM (Traffic Avoidance)
      • Air Traffic Avoidance: ADSB/FLARM
      • Air Traffic Avoidance: UTM
      • Airspeed Sensors
        • TFSlot Airspeed Sensor
      • Barometers
      • Camera
      • Distance Sensors (Rangefinders)
        • Lightware SFxx Lidar
        • Ainstein US-D1 Standard Radar Altimeter
        • LeddarOne Lidar
        • Benewake TFmini Lidar
        • Lidar-Lite
        • TeraRanger
        • Lanbao PSK-CM8JL65-CC5
        • Avionics Anonymous Laser Altimeter UAVCAN Interface
      • ESCs & Motors
        • PWM ESCs and Servos
        • DShot ESCs
        • OneShot ESCs and Servos
        • DroneCAN ESCs
          • Zubax Telega
          • PX4 Sapog ESC Firmware
            • Holybro Kotleta
            • Zubax Orel
        • VESC
      • TBS Crossfire (CRSF) Telemetry
      • FrSky Telemetry
      • Gimbal (Mount) Configuration
      • GPS/Compass
        • ARK GPS
        • Holybro DroneCAN M8N GPS
        • LOCOSYS Hawk A1 GNSS
        • Hex Here2
        • Holybro M8N & M9N GPS
        • Sky-Drones SmartAP GPS
      • Grippers
        • Servo Gripper
      • Optical Flow
        • ARK Flow
        • PMW3901
        • PX4FLOW (Deprecated)
      • Precision Landing
      • Parachute
      • Power Modules/PDB
        • CUAV HV pm
        • CUAV CAN PMU
        • Holybro PM02
        • Holybro PM07
        • Holybro PM06 V2
        • Holybro PM02D (digital)
        • Holybro PM03D (digital)
        • Pomegranate Systems Power Module
        • Sky-Drones SmartAP PDB
      • Satellite Coms (Iridium/RockBlock)
      • Telemetry Radios
        • SiK Radio
          • RFD900 (SiK) Telemetry Radio
          • HolyBro (SIK) Telemetry Radio
        • Telemetry Wifi
          • ESP8266 WiFi Module
          • ESP32 WiFi Module
          • 3DR Telemetry Wifi (Discontinued)
        • Microhard Serial Telemetry Radio
          • ARK Electron Microhard Serial Telemetry Radio
          • Holybro Microhard P900 Telemetry Radio
        • CUAV P8 Telemetry Radio
        • HolyBro XBP9X - Discontinued
      • RTK GPS
        • ARK RTK GPS
        • RTK GPS Heading with Dual u-blox F9P
        • CUAV C-RTK
        • CUAV C-RTK2 PPK/RTK GNSS
        • CUAV C-RTK 9Ps
        • Femtones MINI2 Receiver
        • Freefly RTK GPS
        • Holybro H-RTK-F9P
        • Holybro H-RTK-M8P
        • Holybro H-RTK Unicore UM982 GPS
        • Locosys Hawk R1
        • Locosys Hawk R2
        • Septentrio AsteRx-RIB
        • Septentrio mosaic-go
        • Trimble MB-Two
        • CubePilot Here+ (Discontined)
      • Remote ID
      • Smart Batteries
        • Rotoye Batmon Battery Smartification Kit
      • Tachometers (Revolution Counters)
        • ThunderFly TFRPM01 Tachometer Sensor
      • I2C Peripherals
        • I2C bus accelerators
        • TFI2CADT01 I2C address translator
      • CAN Peripherals
      • DroneCAN Peripherals
        • PX4 DroneCAN Firmware
        • ARK CANnode
    • Companion Computers
      • Pixhawk + Companion Setup
        • RasPi Pixhawk Companion
      • Companion Computer Peripherals
      • Holybro Pixhawk RPI CM4 Baseboard
      • Auterion Skynode
      • Computer Vision
        • Obstacle Avoidance
        • Safe Landing
        • Collision Prevention
        • Path Planning Interface
        • Motion Capture (MoCap)
        • Visual Inertial Odometry (VIO)
          • Realsense T265 Tracking Camera (VIO)
      • Video Streaming
  • Development
    • Getting Started
      • Recommended Hardware/Setup
      • Toolchain Installation
        • MacOS Setup
        • Ubuntu Setup
        • Windows Setup
        • Visual Studio Code IDE
        • Other/Generic Tools
      • Building the Code
      • Writing your First Application
      • Application/Module Template
    • Concepts
      • PX4 Architecture
      • PX4 Flight Stack Architecture
        • Controller Diagrams
      • Events Interface
      • Flight Modes
      • Flight Tasks
      • Control Allocation
      • PWM limit state machine
      • System Startup
      • SD Card Layout
    • Simulation
      • jMAVSim Simulation
        • Multi-Vehicle Sim with JMAVSim
      • Gazebo Simulation
        • Vehicles
        • Multi-Vehicle Sim
      • Gazebo Classic Simulation
        • Vehicles
        • Worlds
        • Multi-Vehicle Sim
      • FlightGear Simulation
        • FlightGear Vehicles
        • Multi-Vehicle Sim with FlightGear
      • JSBSim Simulation
      • AirSim Simulation
      • Multi-Vehicle Simulation
      • Simulate Failsafes
      • HITL Simulation
      • Simulation-In-Hardware
    • Hardware
      • Flight Controller Reference Design
      • Manufacturer’s Board Support Guide
      • Flight Controller Porting Guide
        • PX4 Board Configuration (kconfig)
        • NuttX Board Porting Guide
      • Serial Port Mapping
      • Airframes
        • Adding a New Airframe
      • Device Drivers
      • Telemetry Radio
        • SiK Radio
      • Sensor and Actuator I/O
        • DroneCAN
        • I2C Bus
        • UART/Serial Ports
          • Port-Configurable Serial Drivers
      • RTK GPS (Integration)
    • Middleware
      • uORB Messaging
      • uORB Graph
      • uORB Message Reference
        • ActionRequest
        • ActuatorArmed
        • ActuatorControlsStatus
        • ActuatorMotors
        • ActuatorOutputs
        • ActuatorServos
        • ActuatorServosTrim
        • ActuatorTest
        • AdcReport
        • Airspeed
        • AirspeedValidated
        • AirspeedWind
        • AutotuneAttitudeControlStatus
        • BatteryStatus
        • ButtonEvent
        • CameraCapture
        • CameraStatus
        • CameraTrigger
        • CellularStatus
        • CollisionConstraints
        • CollisionReport
        • ControlAllocatorStatus
        • Cpuload
        • DebugArray
        • DebugKeyValue
        • DebugValue
        • DebugVect
        • DifferentialPressure
        • DistanceSensor
        • Ekf2Timestamps
        • EscReport
        • EscStatus
        • EstimatorAidSource1d
        • EstimatorAidSource2d
        • EstimatorAidSource3d
        • EstimatorBias
        • EstimatorBias3d
        • EstimatorEventFlags
        • EstimatorGpsStatus
        • EstimatorInnovations
        • EstimatorSelectorStatus
        • EstimatorSensorBias
        • EstimatorStates
        • EstimatorStatus
        • EstimatorStatusFlags
        • Event
        • FailsafeFlags
        • FailureDetectorStatus
        • FollowTarget
        • FollowTargetEstimator
        • FollowTargetStatus
        • GeneratorStatus
        • GeofenceResult
        • GimbalControls
        • GimbalDeviceAttitudeStatus
        • GimbalDeviceInformation
        • GimbalDeviceSetAttitude
        • GimbalManagerInformation
        • GimbalManagerSetAttitude
        • GimbalManagerSetManualControl
        • GimbalManagerStatus
        • GpioConfig
        • GpioIn
        • GpioOut
        • GpioRequest
        • GpsDump
        • GpsInjectData
        • Gripper
        • HealthReport
        • HeaterStatus
        • HomePosition
        • HoverThrustEstimate
        • InputRc
        • InternalCombustionEngineStatus
        • IridiumsbdStatus
        • IrlockReport
        • LandingGear
        • LandingGearWheel
        • LandingTargetInnovations
        • LandingTargetPose
        • LaunchDetectionStatus
        • LedControl
        • LogMessage
        • LoggerStatus
        • MagWorkerData
        • MagnetometerBiasEstimate
        • ManualControlSetpoint
        • ManualControlSwitches
        • MavlinkLog
        • MavlinkTunnel
        • Mission
        • MissionResult
        • ModeCompleted
        • MountOrientation
        • NavigatorMissionItem
        • NormalizedUnsignedSetpoint
        • NpfgStatus
        • ObstacleDistance
        • OffboardControlMode
        • OnboardComputerStatus
        • OrbTest
        • OrbTestLarge
        • OrbTestMedium
        • OrbitStatus
        • ParameterUpdate
        • Ping
        • PositionControllerLandingStatus
        • PositionControllerStatus
        • PositionSetpoint
        • PositionSetpointTriplet
        • PowerButtonState
        • PowerMonitor
        • PpsCapture
        • PwmInput
        • Px4ioStatus
        • QshellReq
        • QshellRetval
        • RadioStatus
        • RateCtrlStatus
        • RcChannels
        • RcParameterMap
        • Rpm
        • RtlTimeEstimate
        • SatelliteInfo
        • SensorAccel
        • SensorAccelFifo
        • SensorBaro
        • SensorCombined
        • SensorCorrection
        • SensorGnssRelative
        • SensorGps
        • SensorGyro
        • SensorGyroFft
        • SensorGyroFifo
        • SensorHygrometer
        • SensorMag
        • SensorOpticalFlow
        • SensorPreflightMag
        • SensorUwb
        • SensorSelection
        • SensorsStatus
        • SensorsStatusImu
        • SystemPower
        • TakeoffStatus
        • TaskStackInfo
        • TecsStatus
        • TelemetryStatus
        • TiltrotorExtraControls
        • TimesyncStatus
        • TrajectoryBezier
        • TrajectorySetpoint
        • TrajectoryWaypoint
        • TransponderReport
        • TuneControl
        • UavcanParameterRequest
        • UavcanParameterValue
        • UlogStream
        • UlogStreamAck
        • UwbDistance
        • UwbGrid
        • VehicleAcceleration
        • VehicleAirData
        • VehicleAngularAccelerationSetpoint
        • VehicleAngularVelocity
        • VehicleAttitude
        • VehicleAttitudeSetpoint
        • VehicleCommand
        • VehicleCommandAck
        • VehicleConstraints
        • VehicleControlMode
        • VehicleGlobalPosition
        • VehicleImu
        • VehicleImuStatus
        • VehicleLandDetected
        • VehicleLocalPosition
        • VehicleLocalPositionSetpoint
        • VehicleMagnetometer
        • VehicleOdometry
        • VehicleOpticalFlow
        • VehicleOpticalFlowVel
        • VehicleRatesSetpoint
        • VehicleRoi
        • VehicleStatus
        • VehicleThrustSetpoint
        • VehicleTorqueSetpoint
        • VehicleTrajectoryBezier
        • VehicleTrajectoryWaypoint
        • VtolVehicleStatus
        • Wind
        • YawEstimatorStatus
      • MAVLink Messaging
      • uXRCE-DDS (PX4-ROS 2/DDS Bridge)
    • Modules & Commands
      • Autotune
      • Commands
      • Communication
      • Controllers
      • Drivers
        • Airspeed Sensor
        • Baro
        • Distance Sensor
        • IMU
        • INS
        • Magnetometer
        • Optical Flow
        • Rpm Sensor
        • Transponder
      • Estimators
      • Simulations
      • System
      • Template
    • Debugging/Logging
      • FAQ
      • Consoles/Shells
        • MAVLink Shell
        • System Console
      • Debugging with GDB
        • SWD Debug Port
        • JLink Probe
        • Black Magic/DroneCode Probe
        • STLink Probe
        • Hardfault Debugging
      • Debugging with Eclipse
      • Failure Injection
      • Sensor/Topic Debugging
      • Simulation Debugging
      • Sending Debug Values
      • System-wide Replay
      • Profiling
      • Binary Size Profiling
      • Logging
      • Flight Log Analysis
      • ULog File Format
    • Tutorials
      • Long-distance Video Streaming
      • Connecting an RC Receiver on Linux
    • Advanced Topics
      • Parameters & Configs
      • Package Delivery Architecture
      • Computer Vision
        • Motion Capture (VICON, Optitrack, NOKOV)
      • Installing driver for Intel RealSense R200
      • Switching State Estimators
      • Out-of-Tree Modules
      • STM32 Bootloader
      • System Tunes
      • Advanced Linux Installation Cases
      • Windows Cygwin Toolchain Maintenance
      • Unsupported Developer Setup
        • CentOS Linux
        • Arch Linux
        • Windows VM Toolchain
        • Windows Cygwin Toolchain
        • Qt Creator IDE
    • Platform Testing and CI
      • Test Flights
        • Test MC_01 - Manual Modes
        • Test MC_02 - Full Autonomous
        • Test MC_03 - Auto Manual Mix
        • Test MC_04 - Failsafe Testing
        • Test MC_05 - Indoor Flight (Manual Modes)
      • Unit Tests
      • Continuous Integration
      • MAVSDK Integration Testing
      • ROS Integration Testing
      • Docker Containers
      • Maintenance
  • Drone Apps & APIs
    • Offboard Control from Linux
    • ROS
      • ROS 2
        • ROS 2 User Guide
        • ROS 2 Offboard Control Example
        • ROS 2 Multi Vehicle Simulation
      • ROS 1 with MAVROS
        • ROS/MAVROS Installation Guide
        • ROS/MAVROS Offboard Example (C++)
        • ROS/MAVROS Offboard Example (Python)
        • ROS/MAVROS Sending Custom Messages
        • ROS/MAVROS with Gazebo Classic Simulation
        • Gazebo Classic OctoMap Models with ROS 1
        • ROS/MAVROS Installation on RPi
        • External Position Estimation (Vision/Motion based)
    • DroneKit
  • Contribution (&Dev Call)
    • Dev Call
    • Support
    • Source Code Management
      • GIT Examples
    • Documentation
    • Translation
    • Terminology/Notation
    • Licenses
  • Releases
    • 1.14
    • 1.13
    • 1.12
Powered by GitBook
On this page
  • Signal wiring
  • I2C cables
  • UAVCAN cables
  • SPI
  • UART
  • GPS(UART) & SAFETY
  • GPS
  • Analog signal (power module)
  • SAFETY
  • High-power wiring
  • Cable colour coding
  1. Basic Assembly

Cable Wiring

PreviousVibration IsolationNextCUAV Pixhawk V6X Wiring QuickStart

Last updated 1 year ago

Cables are a common source of , which can cause problems including flyways, "toilet bowling" and generally poor flight. These problems can be avoided by using appropriate cabling in the UAV.

The following basic concepts should be kept in mind when designing drone cabling:

  • High-Power and signal cables should be separated as much as is practical.

  • Cable lengths should be the minimum needed to enable easy handling of wired components. The wire tension should be adequate to survive possible airframe deformations even in a crash landing (wires must not be the first thing to break).

  • Cable loops to reduce excess length should be avoided - use shorter lengths!

  • For digital signals you can decrease the baudrate to reduce radiated energy and increase the robustness of data transfer. This means that you may be able to use longer cables when high data rates are not needed.

Signal wiring

Signalling protocols have different characteristics, and therefore the cables used in each case require slightly different specifications.

This topic provides specific guidance of cabling for different signalling protocols, along with the used by a number different drone hardware vendors.

I2C cables

The is widely used for connecting sensors. Cable colors from several vendors are specified in following table.

Signal
Pixhawk Colors
ThunderFly colors
CUAV colors (I2C/CAN)

+5V

SCL

SDA

GND

The assumes a 1.5k ohm pull-up resistor on SDA and SCL signals in autopilot.

Cable twisting

When using appropriate twisted pair cables, the I²C bus is generally suitable for submeter-scale airframes. For larger aircraft the use of CAN or other differential signaling based interface is generally more reliable.

Pull-up resistors

An oscilloscope measurement is sometimes required to check correct value of pull-up resistors. The signals on the I2C bus should have clear sharp rectangle-like edges and amplitude of few volts. In case the signal has a low amplitude, the value of pull-up resistors is too low and should be decreased. In the case of rounded signals, the value of pull-up resistors is too high.

UAVCAN cables

Signal
Pixhawk
ThunderFly
Zubax
CUAV (I2C/CAN)

+5V

CAN_H

CAN_L

GND

Cable twisting

CAN cables should also be twisted, for exactly the same reason as I2C cables. For CAN the recommended twisting is:

  • 4 turns of both pairs together per 30cm cable length.

SPI

Signal
Pixhawk Color
ThunderFly color

+5V

SCK

MISO

MOSI

CS!

CS2

GND

UART

CTS and RTS are signals that are used to indicate that data is being transmitted on TX/RX pins. This hand-shake mechanism increases reliability of data transfer. CTS and RTS may remain loose when it is not used by the device.

The connecting cable is not crossed. Therefore, it is necessary to connect only the autopilot and peripherals with this straight cable. The device must cross the wiring internally by swapping RX/TX and RTS/CTS pins.

Signal
Pixhawk Color
ThunderFly color

+5V

TX

RX

CTS

RTS

GND

UART signals are common sources of low frequency EMI, therefore the length of the cable should be minimized as much as possible. Cable twisting is not needed for UART cables.

GPS(UART) & SAFETY

Signal
Pixhawk Color
ThunderFly color

+5V

TX

RX

SCL

SDA

SAFETY_SW

SAFETY_SW_LED

+3v3

BUZZER

GND

GPS

Signal
Pixhawk Color
ThunderFly color

+5V

TX

RX

SCL

SDA

GND

The GPS cable connects to both the UART and I2C bus. As twisting of UART is not applicable the length of the cable should be minimized as much as possible.

Analog signal (power module)

Signal
Pixhawk Color
ThunderFly color
CUAV color

VCC

VCC

CURRENT

VOLTAGE

GND

GND

This connector is example of mix of relatively high-power and low voltage signaling. Unfortunately, twisting is applicable for high-power GND and VCC wires only. That does not help much for noisy reading of analog signals by autopilot.

SAFETY

Signal
Pixhawk Color
ThunderFly color

SAFE_VCC

SAFETY_SW_LED

SAFETY_SW

BUZZER

+5V

GND

High-power wiring

For high power wiring the most important design criteria is having an appropriate wire thickness, in order to allow sufficient current to flow. The general cross section requirement is area of 1 mm² per 8A of wire current.

While rarely practical, it is beneficial to have positive and negative wires twisted together.

EMI from high power cabling has a significant effect on magnetometers. For this reason a large seapration between high-power cables and navigation magnetometers is always required.

Cable colour coding

Color coding signal wires can help identify particular cables, making it easier to assemble your drone.

A colour coding scheme designed for easy cable identification might follow the following rules:

  • The red and black colors are reserved for power.

  • The same signal type should have the same colour.

  • Color of the signal does not repeat in the connector for wires adjacent to each other.

  • Wiring harnesses of the same pin count have to have a unique color sequence. This determines the cable type. (This is especially useful on photographs used in a manual).

An example of a cable colouring designed to these rules is:

Color
Name
Preferred usage

Red

Power voltage

Green

General purpose signal

White

General purpose signal

Yellow

General purpose signal

Blue

Power return, Open-collector control signal

Black

GND, Power return ground

:::note The above rules were provided by Thunderfly and are used in their cable design.

The cable colour-coding for Thunderfly and some other vendors are given in the sections below. The pin labels correspond to the pinout on the autopilot side. All cables are straight (1:1). If they require crossover (e.g. UART), this should be solved by internal connection of the devices. :::

Red

Red

Red

Black

Yellow

White

Black

Green

Yellow

Black

Black

Black

I2C bus signal cross-talk and electromagnetic compatibility can be greatly improved by proper twisting of the cable wires. is especially important for sensor wiring.

10 turns for each pair SCL/+5V and SDA/GND per 30cm cable length.

4 turns of both pairs together per 30cm cable length.

:::note This turns/cable-length recommendation has been successfully used with I2C sensors including the and . :::

Pull-up resistors are required for all ends of an I2C bus. This acts both as and as bus idle signal generator.

Red

Red

Red

Red

Black

White

White

White

Black

Yellow

Yellow

Yellow

Black

Black

Black

Black

10 turns for each pair GND/+5V and CAN_L/CAN_H per 30cm cable length.

is synchronous serial communication interface used for connecting faster sensors and devices. This protocol is commonly use is for connecting sensors or special telemetry modems.

Red

Red

Black

Yellow

Black

Blue

Black

Green

Black

White

Black

Blue

Black

Black

UART is used to connect peripherals to the autopilot. By default, UART does not support networking and therefore it directly connects two devices together. It is often used to connect an autopilot and a .

Red

Red

Black

White

Black

Green

Black

Blue

Black

Yellow

Black

Black

are generally very sensitive to EMI. Therefore thse should be mounted far away from RF sources (high-power cabling, ESCs, radio modems and its antenna). This may be insufficient if the cabling is badly designed.

Red

Red

Black

White

Black

Green

Black

Yellow

Black

Green

Black

White

Black

Blue

Black

Red

Black

Blue

Black

Black

Red

Red

Black

White

Black

Green

Black

Yellow

Black

Green

Black

Black

Red

Red

Red

Black

Red

Red

Black

White

White

Black

Yellow

Yellow

Black

Black

Black

Black

Black

Black

Red

Red

Black

Blue

Black

White

Black

Blue

Black

Red

Black

Black

Most manufacturers use red for the high voltage line and black for ground. Other colouring is at the manufacturer discretion. The requires only that the Voltage Common Collector (VCC) pin/cable be red.

Twisted pairs
ThunderFly TFSLOT airspeed sensor
TFRPM01 Revolution Counter
signal termination
SPI
optical flow
radio modem
GPS receivers and magnetometers
Pixhawk connector standard
electromagnetic interference (EMI)
I2C bus
Dronecode standard
colour coding
I²C JST-GH cable
I²C JST-GH connector detail
CAN JST-GH cable
red
red
red
black
yellow
white
black
green
yellow
black
black
black
red
red
red
red
black
white
white
white
black
yellow
yellow
yellow
black
black
black
black
red
red
black
yellow
black
blue
black
green
black
white
black
blue
black
black
red
red
black
white
black
green
black
blue
black
yellow
black
black
red
red
black
white
black
green
black
yellow
black
green
black
white
black
blue
black
red
black
blue
black
black
red
red
black
white
black
green
black
yellow
black
green
black
black
red
red
red
black
red
red
black
white
white
black
yellow
yellow
black
black
black
black
black
black
red
red
black
blue
black
white
black
blue
black
red
black
black
red
green
white
yellow
blue
black