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)
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        • NXP RDDRONE-FMUK66 FMU
        • Sky-Drones AIRLink
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        • 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)
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      • Airspeed Sensors
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      • Camera
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        • Avionics Anonymous Laser Altimeter UAVCAN Interface
      • ESCs & Motors
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        • VESC
      • TBS Crossfire (CRSF) Telemetry
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        • Hex Here2
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      • Grippers
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      • Satellite Coms (Iridium/RockBlock)
      • Telemetry Radios
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          • RFD900 (SiK) Telemetry Radio
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        • 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
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On this page
  • Trigger Configuration
  • Trigger Modes
  • Trigger Interface Backends
  • Trigger Output Pin Configuration
  • Other Parameters
  • Camera Capture
  • MAVLink Command Interface (Directly Connected Cameras)
  • MAVLink Cameras
  • Testing Trigger Functionality
  • Sony QX-1 example (Photogrammetry)
  • Trigger Settings
  • Camera Configuration
  • Mission Planning
  • Geotagging
  • Reconstruction
  • Camera-IMU sync example (VIO)
  • Step 1
  • Step 2
  • Step 3
  • Step 4
  1. Hardware (Drones&Parts)
  2. Flight Controller Peripherals

Camera

PreviousBarometersNextDistance Sensors (Rangefinders)

Last updated 1 year ago

PX4 can be configured to connect physical outputs to trigger a camera, or it can be used with a .

:::note We recommend that you use a MAVLink camera as this allows comprehensive control of cameras via the . Directly connected cameras only support of MAVLink camera commands. :::

Whenever a camera is triggered, the MAVLink message is published containing a sequence number (i.e. the current session's image sequence number) and the corresponding timestamp. This timestamp can be used for several applications, including: timestamping photos for aerial surveying and reconstruction, synchronising a multi-camera system or visual-inertial navigation.

Cameras can also (optionally) signal PX4 at the exact moment that a photo/frame is taken using a camera capture pin. This allows more precise mapping of images to GPS position for geotagging, or the right IMU sample for VIO synchronization, etc.

Trigger Configuration

Camera triggering is usually configured from the QGroundControl section.

Trigger Modes

Mode
Description

0

Camera triggering is disabled.

1

2

Switches the intervalometer constantly on.

3

Triggers based on distance. A shot is taken every time the set horizontal distance is exceeded. The minimum time interval between two shots is however limited by the set triggering interval.

4

triggers automatically when flying a survey in Mission mode.

:::note If it is your first time enabling the camera trigger app, remember to reboot after changing the TRIG_MODE parameter. :::

Trigger Interface Backends

Number
Description

1

2

3

Enables the MAVLink interface. In this mode, no actual hardware output is used. Only the CAMERA_TRIGGER MAVLink message is sent by the autopilot (by default, if the MAVLink application is in onboard mode. Otherwise, a custom stream will need to be enabled).

4

Trigger Output Pin Configuration

The trigger pins can be set by assigning the Camera_Trigger function on any FMU output. If using trigger setup that requires two pins (e.g. Seagull MAP2) you can assign to any two outputs.

Note however that once an output has been used for camera triggering, the whole PWM group cannot be used for anything else (you can't use another output in the group for an actuator or motor, say).

:::note At time of writing triggering only works on FMU pins:

  • On a Pixhawk flight controller that has both FMU and I/O boards FMU pins map to AUX outputs (e.g. Pixhawk 4, CUAV v5+) .

  • A controller that only has an FMU, the pins map to MAIN outputs (e.g. Pixhawk 4 mini, CUAV v5 nano). :::

Other Parameters

Parameter
Description

Relevant only while using the GPIO interface. Sets the polarity of the trigger pin. Active high means that the pin is pulled low normally and pulled high on a trigger event. Active low is vice-versa.

Defines the time between two consecutive trigger events in milliseconds.

Defines the time in milliseconds the trigger pin is held in the "active" state before returning to neutral. In PWM modes, the minimum is limited to 40 ms to make sure we always fit an activate pulse into the 50Hz PWM signal.

Camera Capture

Cameras can also (optionally) use a camera capture pin to signal the exact moment when a photo/frame is taken. This allows more precise mapping of images to GPS position for geotagging, or the right IMU sample for VIO synchronization, etc.

:::note At time of writing camera capture only works on FMU pins:

  • On a Pixhawk flight controller that has both FMU and I/O boards FMU pins map to AUX outputs (e.g. Pixhawk 4, CUAV v5+).

  • A controller that only has an FMU, the pins map to MAIN outputs (e.g. Pixhawk 4 mini, CUAV v5 nano). :::

PX4 detects a rising edge with the appropriate voltage level on the camera capture pin (for Pixhawk flight controllers this is normally 3.3V). If the camera isn't outputting an appropriate voltage, then additional circuitry will be required to make the signal compatible.

MAVLink Command Interface (Directly Connected Cameras)

When using a camera connected to the flight controller as described in this document (e.g. using the GPIO, PWM or seagull backend interfaces) the camera driver supports the following subset of MAVLink commands:

Command Parameter
Description

Param #1

Trigger enable/disable. 1: enable (start), 0: disable.

Param #2

Reset trigger sequence. 1: reset, any other value does nothing.

Param #3

Pause triggering, but without switching the camera off or retracting it. 1: pause, 0: restart.

This is used by the GCS to test-shoot the camera from the user interface. The trigger driver does not support all camera control parameters defined by the MAVLink spec.

Command Parameter
Description

Param #5

Trigger one-shot command (set to 1 to trigger a single image frame).

This command is autogenerated during missions to trigger the camera based on survey missions from the GCS.

This accepts param1 to param4 as defined in the MAVLink message definition. The shutter integration setting (param2) is only obeyed with a GPIO backend.

MAVLink Cameras

In this case MAVLink camera messages are forwarded to a MAVLink camera for handling (although PX4 will still emit the CAMERA_TRIGGER when a trigger command is received).

Testing Trigger Functionality

:::warning The following sections are out of date and need retesting. :::

  1. On the PX4 console:

    camera_trigger test
  2. From QGroundControl:

    Click on Trigger Camera in the main instrument panel. These shots are not logged or counted for geotagging.

Sony QX-1 example (Photogrammetry)

In this example, we will use a Seagull MAP2 trigger cable to interface to a Sony QX-1 and use the setup to create orthomosaics after flying a fully autonomous survey mission.

Trigger Settings

The recommended camera settings are:

  • TRIG_INTERFACE=2 (Seagull MAP2).

  • TRIG_MODE=4 (Mission controlled).

  • Leave the remaining parameters at their defaults.

You will need to connect the Seagull MAP2 to FMU pins on your autopilot. The other end of the MAP2 cable will go into the QX-1's "MULTI" port.

Camera Configuration

We use a Sony QX-1 with a 16-50mm f3.5-5.6 lens for this example.

To avoid autofocus and metering lag when the camera is triggered, the following guidelines should be followed:

  • Manual focus to infinity

  • Set camera to continuous shooting mode

  • Manually set exposure and aperture

  • ISO should be set as low as possible

  • Manual white balance suitable for scene

Mission Planning

Geotagging

Download/copy the logfile and images from the flight and point QGroundControl to them. Then click on Start Tagging.

Reconstruction

Camera-IMU sync example (VIO)

In this example, we will go over the basics of synchronising IMU measurements with visual data to build a stereo Visual-Inertial Navigation System (VINS). To be clear, the idea here isn't to take an IMU measurement exactly at the same time as we take a picture but rather to correctly time stamp our images so as to provide accurate data to our VIO algorithm.

The autopilot and companion have different clock bases (boot-time for the autopilot and UNIX epoch for companion), so instead of skewing either clock, we directly observe the time offset between the clocks. This offset is added or subtracted from the timestamps in the MAVLink messages (e.g. HIGHRES_IMU) in the cross-middleware translator component (e.g. MAVROS on the companion and mavlink_receiver in PX4). The actual synchronisation algorithm is a modified version of the Network Time Protocol (NTP) algorithm and uses an exponential moving average to smooth the tracked time offset. This synchronisation is done automatically if MAVROS is used with a high-bandwidth onboard link (MAVLink mode onboard).

For acquiring synchronised image frames and inertial measurements, we connect the trigger inputs of the two cameras to a GPIO pin on the autopilot. The timestamp of the inertial measurement from start of exposure and a image sequence number is recorded and sent to the companion computer (CAMERA_TRIGGER message), which buffers these packets and the image frames acquired from the camera. They are matched based on the sequence number (first image frame is sequence 0), the images timestamped (with the timestamp from the CAMERA_TRIGGER message) and then published.

The following diagram illustrates the sequence of events which must happen in order to correctly timestamp our images.

Step 1

First, set the TRIG_MODE to 1 to make the driver wait for the start command and reboot your FCU to obtain the remaining parameters.

Step 2

For the purposes of this example we will be configuring the trigger to operate in conjunction with a Point Grey Firefly MV camera running at 30 FPS.

  • TRIG_INTERVAL: 33.33 ms

  • TRIG_POLARITY: 0 (active low)

  • TRIG_ACT_TIME: 0.5 ms. The manual specifies it only has to be a minimum of 1 microsecond.

  • TRIG_MODE: 1, because we want our camera driver to be ready to receive images before starting to trigger. This is essential to properly process sequence numbers.

Step 3

Wire up your cameras to your AUX port by connecting the ground and signal pins to the appropriate place.

Step 4

The different , and are described below (these can also be set directly from ).

:::note The camera settings section is not available by default for FMUv2-based flight controllers (e.g. 3DR Pixhawk) because the camera module is not automatically included in firmware. For more information see . :::

Four different modes are supported, controlled by the parameter:

Works like a basic intervalometer that can be enabled and disabled by using the MAVLink command MAV_CMD_DO_TRIGGER_CONTROL. See for more details.

The camera trigger driver supports several backends - each for a specific application, controlled by the parameter:

Enables the GPIO interface. The AUX outputs are pulsed high or low (depending on the TRIG_POLARITY parameter) every duration. This can be used to trigger most standard machine vision cameras directly. Note that on PX4FMU series hardware (Pixhawk, Pixracer, etc.), the signal level on the AUX pins is 3.3v.

Enables the Seagull MAP2 interface. This allows the use of the to interface to a multitude of supported cameras. Pin/Channel 1 (camera trigger) and Pin/Channel 2 (mode selector) of the MAP2 should be connected to the lower and higher mapped . Using Seagull MAP2, PX4 also supports automatic power control and keep-alive functionalities of Sony Multiport cameras like the QX-1.

Enables the generic PWM interface. This allows the use of or servos to trigger your camera.

Camera trigger pins are set in the QGroundControl configuration screen.

The full list of parameters pertaining to the camera trigger module can be found on the page.

Camera capture/feedback is enabled in PX4 by setting . The pin used for camera capture is then set in the QGroundControl configuration screen by assigning the Camera_Capture function on any FMU output.

Cameras that have a hotshoe connector (for connecting a flash) can usually be connected via a hotshoe-adaptor. For example, the is an optocoupler that decouples and shifts the flash voltage to the Pixhawk voltage. This slides into the flash slot on the top of the camera. The red and black ouptputs are connected to the servo rail/ground and the white wire is connected to the input capture pin.

:::note PX4 emits the MAVLink message on both camera trigger and camera capture. If camera capture is configured, the timestamp from the camera capture driver is used, otherwise the triggering timestamp. :::

- Accepted in "command controlled" mode (TRIG_MODE 1).

- Accepted in all modes.

- Accepted in "mission controlled" mode (TRIG_MODE 4)

- Mission command to set a camera auto mount pivoting oblique survey.

PX4 can also be configured to use a with a MAVLink camera.

MAVLink cameras are recommended because directly connected cameras only support of the available MAVLink camera messages and commands. MAVLink cameras potentially offer much more control over a camera using the .

You can verify the geotagging using a free online service like . Note that Pic2Map is limited to only 40 images.

We use for 3D reconstruction.

You will have to modify your driver to follow the sequence diagram above. Public reference implementations for cameras and for cameras are available.

Actuators
Seagull #SYNC2 Universal Camera Hot Shoe Adapter
CAMERA_TRIGGER
MAV_CMD_DO_TRIGGER_CONTROL
MAV_CMD_DO_DIGICAM_CONTROL
MAV_CMD_DO_SET_CAM_TRIGG_DIST
MAV_CMD_OBLIQUE_SURVEY
Pic2Map
Pix4D
IDS Imaging UEye
IEEE1394 compliant
parameters
trigger modes
backend interfaces
trigger output configuration
MAVLink trigger interface backend
MAVLink Camera Protocol
a small subset
infrared triggers
command interface
Seagull MAP2
camera trigger pins
camera protocol
CAMERA_TRIGGER
Vehicle Setup > Camera
MAVLink camera
a small subset
Actuators
Finding/Updating Parameters > Parameters Not In Firmware
Trigger pins
Seagull SYNC#2
QGC Test Camera
photogrammetry
QGC Survey Polygon
QGC Survey Parameters
QGC Geotagging
GeoTag
Mermaid sequence diagram
TRIG_MODE
TRIG_INTERFACE
parameter reference
CAM_CAP_FBACK = 1
TRIG_INTERVAL
TRIG_POLARITY
TRIG_INTERVAL
TRIG_ACT_TIME