MSP OSD

ArduPilot supports several types of MSP OSDs using MSP based protocols:

  • Telemetry based OSDs such as DJI FPV Goggles V1/V2, DJI Goggles RE, FatShark ByteFrost, FatShark SharkByte, MWOSD , etc

  • DisplayPort (sometimes incorrectly referred to as CANVAS MODE) based OSD’s such as FatShark SharkByte (fw 09042021 and later), DJI goggles using the wtf-os firmware and msdp-osd module, and MWOSD’s DisplayPort mode/firmware

Telemetry based OSDs will render OSD panel items on screen with their own engine, so ArduPilot has no control of how the items look. Another limit of telemetry based OSDs is that there’s no way for ArduPilot to add new panel items at will, it’s the vendor’s responsibility to add new features by rolling out new firmware releases.

DisplayPort, on the contrary, is an MSP protocol extension that allows to remotely draw text on compatible external OSDs, DisplayPort is also known (incorrectly) as CANVAS MODE. Basically it’s a remote text only frame buffer that uses local fonts (local to the rendering engine i.e. the OSD hardware) to render strings sent via MSP.

Telemetry based OSD

DJI V1 FPV Goggles

../_images/msp_dji_fpv_goggles.jpeg

DJI Goggles RE

../_images/msp_dji_goggles_re.jpeg

Features

  • ArduPilot currently supports all of the OSD panel items provided by the V1 and V2 DJI FPV Goggles, details are given in the table below.

  • Changing display units other than metric and imperial are not currently supported.

  • Multiple screens and remote switching of those screens is supported.

  • Displaying statistics on a dedicated screen is supported, see below for details.

  • Warning levels for RSSI, Voltage, etc. currently not supported

Configuration

To enable MSP OSD, set the following parameters ( example using SERIAL port 2 as the port to attach to the DJI Air unit using both TX and RX lines):

  • OSD_TYPE = 3 if no integrated OSD is being used in order to activate the OSD code. If an integrated OSD is present and the user wishes to have both OSDs , then OSD_TYPE = 1 will activate the on-board OSD as well as providing screens for the MSP OSD function. For example, on vehicles using the DJI goggles/air system for medium range, but still running a long range VTX using the internal OSD for when the vehicle exceeds the range of the HD DJI Goggles. This configuration could use one OSD screen optimized for DJI Goggles, and another for the integrated OSD and the user can switch between them depending on which video system is being viewed.

  • SERIAL2_PROTOCOL = 33

  • MSP_OPTIONS = 0 (polling mode)

Note

DJI Custom OSD must be enabled: in SETTINGS->DISPLAY->CUSTOM OSD menu of goggles

OSD Panel Items

OSD Parameter

Notes

OSDn_ALTITUDE

Home relative altitude

OSDn_ARMING

Arming status, hidden when armed otherwise showing DISARMED

OSDn_ASPEED

Please refer to OSDn_GSPEED for more info on enabling airspeed display

OSDn_BAT_VOLT

First battery voltage

OSDn_BATBAR

First battery remaining percentage rendered as a bar based on declared capacity and consumed mAh

OSDn_BATUSED

First battery consumed mAh

OSDn_CELLVOLT

First battery average cell voltage, if automatic cell detection fails please override with MSP_OSD_NCELLS

OSDn_CLK

Realtime clock (requires GPX fix)

OSDn_CRSSHAIR

Artificial horizon is not supported so crosshair is often kept hidden

OSDn_CURRENT

First battery current

OSDn_ESCTEMP

On DJI V1/V2 Goggles this will report the highest ESC temperature

OSDn_FLTMODE

DJI hardware does not support ArduPilot’s flight modes! This item will generally be blank and only show !FS! while in failsafe!

OSDn_GPSLAT

GPS Latitude in decimal format

OSDn_GPSLONG

GPS Longitude in decimal format

OSDn_GSPEED

This item shows ground speed unless OSDn_ASPEED_EN = 1 in which case it will show true airspeed if an airspeed sensor is present or estimated airspeed otherwise. The position on screen is set by OSDn_GSPEED_X and OSDn_GSPEED_Y regardless of the value of OSDn_ASPEED_EN

OSDn_HEADING

Not supported by DJI V1/V2 Goggles

OSDn_HOMEDIR

Rotating arrow pointing to home

OSDn_HOMEDIST

Distance from home

OSDn_HORIZON

Not supported by DJI V1/V2 Goggles

OSDn_MESSAGE

This will display status text messages as rolling text. Status text messages will be hidden after a couple seconds and the panel will show the current flightmode. If OSDn_WIND_EN is set to 1, this item also displays wind info next to the current flight mode as a rotating arrow and speed.

OSDn_PITCH

Pitch angle

OSDn_POWER

Instant power calculated as voltage * current

OSDn_ROLL

Roll angle

OSDn_RSSI

Rssi as configured in RSSI_TYPE: RSSI Type

OSDn_SATS

On DJI V1/V2 Goggles when there’s no fix it will report 14 sats, this is a known DJI bug

OSDn_SIDEBARS

Not supported by DJI V1/V2 Goggles

OSDn_VSPEED

Vertical speed

OSDn_WIND

Please refer to OSDn_MESSAGE for wind speed and direction rendering

OSD Panel Item Configuration

Each OSD panel item uses a set of three variables to be set:

  • OSDn_<ITEM>_EN - activates the respective panel item on screen “n” when set to 1.

  • OSDn_<ITEM>_X and OSDn_<ITEM>_Y set the horizontal and vertical position of the item, starting with X = 0 and Y = 0 in the upper left corner of your screen.

Note

ArduPilot calculates a sensor-less airspeed estimate that is used if no sensor is present or fails. ARSPD_TYPE must be set to zero in order to display this value as the airspeed item, if no sensor is present.

Screens and screen switching

For multiple screen layouts, each screen’s “OSD” parameter label is trailed by a number, starting with “1”. For example, OSDn_<ITEM>_x is a parameter “x” associated with screen 1’s “ITEM” panel.

  • Set OSDn_<ITEM>_EN =1 to enable screen “n” display of this item. This allows one to set individual items active on one screen but have them switched off on another screen. Up to 4 screens are optionally available, and can be individually enabled.

  • Set parameters OSDn_CHAN_MIN and OSDn_CHAN_MAX to adjust RC channel pwm limits to use for switching to a respective screen. Be sure to have the ranges non-overlapping.

There are different switch-method options to meet individual RC systems switch layout requirements. These can be set by parameter: OSD_SW_METHOD. The options are:

  • 0 = switches to next screen if the set RC channel’s (OSD_CHAN) value is changed

  • 1 = directly selects a screen based on the set pwm limits for each respective screen. RC channel value must change for new pwm value to be recognized.

  • 2 = toggles screens on a low to high transition of set RC channel. keeps toggling to next screen every second while channel value is kept high

Displaying statistics on a dedicated screen

Displaying statistics on a dedicated screen requires enabling at least one extra screen by setting the respective OSDn_ENABLE to 1. By default, ArduPilot has only one screen active so in a typical setup one would set (OSD2_ENABLE) = 1 and then enabling the OSD stats panel on screen 2 by setting (OSD2_STATS_EN) = 1.

When the OSD switches to this screen it will check the value of the OSD2_STATS_EN parameter and if enabled it will override the default behavior of the following OSD items:

  • OSDn_MESSAGE will display STATS followed by flight time

  • OSDn_ALTITUDE will display max altitude

  • OSDn_BAT_VOLT will display min voltage

  • OSDn_CURRENT will display max current

  • OSDn_GSPEED will display max ground speed (or airspeed if OSDn_ASPEED_EN is set to 1)

  • OSDn_HOMEDIST will alternates max distance from home and total traveled distance every 2 seconds

  • OSDn_RSSI will display min rssi

DisplayPort OSD

FatShark’s SharkByte using ArduPilot custom fonts

../_images/msp_osd_displayport.jpg

Features

DisplayPort OSDs can render all the panel items supported by the ArduPilot’s onboard OSD. Features such as multiple screen switching, multiple units and statistics are supported as well, please refer to the onboard OSD documentation for more info.

By setting MSP_OPTIONS bit 2 to 1 (value = 4) one can force ArduPilot to impersonate Betaflight and use a Betaflight compatible font indexes for the font table integrated in the remote OSD system.

This is required if the remote OSD system does not have an ArduPilot compatible fonts table. MWOSD and DJI goggles using the wtf-os/msp-osd firmware already support custom fonts locally and therefore does not require this hack, while HDzero recently added an ArduPilot compatible font set.

Note

the direction arrows will be reversed since ArduPilot and Betaflight use direction arrows in their font tables that are 180 deg different than each other.

Default behavior (MSP_OPTIONS = 0) is to use the ArduPilot font table’s indexes.

Configuration

To enable MSP DisplayPort OSD, set the following parameters (using SERIAL port 2 as the port to attach to the Air unit using both TX and RX lines):

DJI Goggles with WTF-OSD firmware

Depending on existing firmware revision, you can modify the firmware of the DJI goggles with a third party “rooting” and OS replacement that allows using DisplayPort protocol and gives the same capabilities as that of the ArduPilot internal OSD in terms of panel items, screens, and placement.

In addition, you can have either standard definition (SD) fonts, or high definition (HD) fonts, as well as colors for the fonts. The steps required to use this are:

  1. Root the goggles and air unit

  2. Install WTFOS

  3. Use the “Package Manager” to install the msp-osd module

  4. Install the font package as instructed by the msp-osd readme in the root directory of the goggles SD card

  5. Configure OSD_TYPE = 5 and SERIAL2_PROTOCOL = 42

Now you can select to display either the SD or HD fonts using OSDx_TXT_RES for each OSD screen enabled.

The SD font’s positions are set on a 30x16 X/Y position grid as normal, the HD uses a 50x18 grid.

Sets of fonts converted from ArduPilots standard font sets are provided on the msp-osd module site, but additional DJI-style SD/HD sets with color icons are available here

Note

the font set above will need to be renamed and placed in the appropriate subdirectory on the goggle’s SD card if usinng a version after mspd-osd ver 0.6.7. Follow the readme for whatever version you are using of msp-osd.

Testing OSD with SITL

MSP OSD functionality can be tested and panel items adjusted without autopilot or video hardware using the Software In The Loop (SITL) simulator setup. Follow those SITL-Instructions to setup a simulation environment. Run the simulator on current source code using --osdmsp option to build the OSD code into the simulator. For example, for a plane simulation:

sim_vehicle.py -v ArduPlane --console --osdmsp

A graphical DJI style MSP OSD simulation in a separate window will be opened with the other simulation windows using a typical set of OSD panel parameters, located at libraries/AP_MSP/Tools/osdtest.parm . Then the OSD elements can be customized by their parameters using the MSP OSD emulation program to visualize the OSD.

Note

You could also use these parameters to initially setup the MSP OSD configuration for use with goggles, but you may have to change the SERIALx_PROTOCOL parameter to match the actual serial port that you will be using.

Note

The emulation supports multiple screens and stats, but not yet Display Port

Note

The emulation does not support units other than metric

../_images/msp_osd_python.png ../_images/msp_osd_python_stats.png

By changing the OSD panel items’ parameters, a live update on their placement can be seen in this emulator.

Using Mission Planner to Configure the Layout

Mission Planner(MP) has a tab in its CONFIG menu to configure the on-board OSD many autopilots integrate. This same configuration tab can be used to configure the OSD panels. In fact, you can do that while the SITL program and MSP OSD emulation window are active by connecting Mission Planner running on the same computer, or networked computer, to MAVProxy, using this command in MAVProxy:

output add <ip address of box running Mission Planner>:14550

Note

if MP is running on the same PC, the ip address would be 127.0.0.1 (local host address)

Video