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OpenOSD-X

OpenOSD-X is a project that integrates analog OSD and VTX functionality.

Features

• Enables 5.8GHz analog video output when combined with a digital-only flight controller (without analog OSD)
• Provides both SD version (same resolution as MAX7456) and HD version (supports more information display)
• Font updates via Betaflight Configurator
• Uses the compact and cost-effective STM32G431KBT, allowing standalone OSD operation

Development in Progress

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Connection Example

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Configuration

1. Connect the camera, OpenVTX, FC, and PC

2. Power all devices

   • USB power alone may not be sufficient; connect a battery if required

3. Launch Betaflight Configurator

4. Serial Port Setup

   • Set the port connected to OpenOSD-X to VTX (MSP+DisplayPort)
   • Power cycle all devices to read OSD and VTX parameters

5. OSD Settings

   • Select HD (not NTSC/PAL)
   • Resolution is automatically configured depending on the camera and firmware

6. VTX Settings

   • VTX table is preloaded in OpenOSD-X and set automatically
   • Configure channel and output power

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Firmware Update

Firmware updates are possible via FC (Serial-Passthrough) or USB-Serial (FTDI).

1. Connect the OpenVTX board, FC, and PC

2. Run the Python script (auto-detects COM port and flashes firmware):

   python flashOpenOSD-X.py hex-file

   ⚠ Requires Betaflight serial port (DisplayPort-VTX) to be enabled

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HEX Files

Latest HEX files are available here: https://github.com/OpenOSD-X/OpenOSD-X/actions

Releases are provided per board type and resolution:

• openosd-x_breakoutboard_sd.hex …… Standard resolution for breakout board
• openosd-x_breakoutboard_hd.hex …… High resolution for breakout board

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Font Update

Font updates can be performed directly from the Betaflight Configurator.

• Requires Betaflight 2025.12.0 or later
• Use a Betaflight firmware build with the custom definition USE_MSP_DISPLAYPORT_FONT enabled.
• Use a Configurator version that is compatible with the firmware.

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Developer Information

Reference Schematics and Block Diagrams

https://github.com/OpenOSD-X/OpenOSD-X/tree/main/doc

Testing with Development Boards

The OSD portion can be tested on ST Nucleo or WeACT development boards. OpenOSD-X targets the STM32G431KBT but also works with STM32G431C and STM32G473.

Initial Flashing

Flash the following two HEX files using ST-LINK or similar:

• Application firmware: openosd-x_***.hex
• Bootloader: openosd-x_bootloader.hex

VPD Table

The VPD table configures the PA for the VTX. If VTX is not used, this table is unnecessary.

Example (for breakout board):

	5600MHz	5650MHz	5700MHz	5750MHz	5800MHz	5850MHz	5900MHz	5950MHz	6000MHz
14dBm (25mW)	1300mV	1330mV	1345mV	1400mV	1480mV	1590mV	1670mV	1710mV	1760mV
20dBm (100mW)	1910mV	1970mV	1980mV	2120mV	2270mV	2430mV	2540mV	2620mV	2750mV

When manufacturing a custom board, you must create a VPD table tailored to your PA and component selection. Use the dev firmware to measure and generate the required VPD table.

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Development Firmware

Used for TX adjustment and VPD table generation.

Setup

[PC (Terminal)] --- UART (115200bps) --- [OpenOSD-X (dev version)] --- 5.8GHz --- [Measuring Equipment]

Command Example

> vtx_set 5800 1000    ...... Example: 5800MHz, VPD target voltage = 1000mV

Adjust the VPD target voltage until the desired TX output is achieved. The collected values form the VPD table.

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Developers Channel

Join the dedicated Discord server: https://discord.gg/YtnWQyGRB6

Open Source

OpenOSD-X is open-source software provided free of charge and without warranty. Parts of the source code are based on the following projects:

• betaflight
• OpenVTx
• OpenPixelOSD