Version 3.2 – with NuttX ROS

Starting with version 3.2 we will start to support on VRBRAIN the NuttX real time operating system.

The NuttX environment we used for our boards derives directly from the great work of the PX4 team ( and 3DR (

ROS greatly modifies the way the flying code will work on the VRBRAIN, this is why it took us some time to fine tune it.

With this version it will also be possible to download directly on the board the firmware from the Mission Planner reducing the time it takes to upload new versions.

Version 3.2 is compatible with the following boards: VRBRAIN 4.5 with SD card reader, VRμBRAIN and VRBRAIN 5

Here you will find instructions and download links for firmware update.


The new generation of VRBRAIN (micro and 5.x) now supports the download of firmware from Mission Planner.

One has to note that official firmware on Mission Planner will allow the use of only PPMSUM or SBUS.

If you need to use standard PWM, or want to try out the latest betas, please follow these instructions:

Open this link: VRX firmware complete list and go to (Copter, Plane or Rover)–>CUSTOM–>stable–>PPM.

and choose the correct file for your frame.

Then upload custom firmware (.vrx files) from the Mission Planner Initial Setup–>Install firmware–>custom firmware.



We decided to give VRBRAIN 4.5 users a chance to use 3.2 with NuttX although it will be limited in some functionalites.

These are the limitations:

  1. You need a micro-SD card adapter to be able to log flight data. The autopilot will still work without, but using this you will be able to log thousands of flights and you will be able to log all sensors on the board. Micro SD card adapter can be ordered to info[at]
  2. Only PPMSUM and SBUS (or FrSky SBUS) are fully supported (up to 14 Channels). Standard PWM input is limited to 6 channels at the moment. This is due to the fact that the RTOS uses more interrupts to work. We are working on an update though.
  3. One of the three serials had to be used for the USB drivers, so it will be possible to use only 2 serials (1 for GPS and 1 for telemetry)

These are the advantages of using the new firmware with RTOS:

  1. Unlimited use of logs if using an SD card.
  2. It is possible to use up to 2 magnetometers and 2 IMUs at the same time.
  3. Fully compatible with Mission Planner firmware upload.
  4. Use of advanced features like rally points and terrain following.
  5. Compiled firmware versions for plane, copter and rover.


To use the new firmware and to ease the upgrade of following versions there are a few steps you need to do.

Steps 1 to 3 are only for a first time setup, after you successfully uploaded the bootloader, follow only steps 4 to 9!

  1. Install the drivers for the VRBRAIN boards from this link
  2. Download the Bootloader’s dfu from here vrbrainv45_bl.dfu
  3. Upload bootloader as you would do with standard firmware (follow the instructions in:
  4. Connect USB and you will notice leds blinking in a non standard Way. Yellow led blinking rapidly and Red led off.
  5. Now open Mission Planner, go to “INITIAL SETUP” –> Install Firmware, choose your frame and version 3.1.15 (for now we will store version 3.2 there until it is officially released).
  6. If a Message box appear, follow the instructions: disconnect the board from USB, click OK and then reconnect the board.
  7. If no message appears and you see a “connecting” unplug the board and plug it back again.
  8. After upload, disconnect and reconnect the board.
  9. Done!

For firmware updates, after the first install, after you select the firmware and the board goes into bootloader mode (Yellow led blinking fast) you need to disconnect and reconnect the board, otherwise it will not be recognized.

To upload PWM input firmware please follow this link:

VRBRAIN Firmware

And select the .vrx file from the folder of your preferred frame.

Open Mission planner and click on “Load custom firmware” in the InstallFirmware tab under INITIAL SETUP.

 A few changes in the layout of the pins respect to previous version:

  1. PPMSUM is now on PIN 7 of the INPUIT rail.
  2. SBUS is still on PIN 6 of the input rail and still needs a physical inverter to be used. (VRBRAIN5 supports SBUS without external hardware).
  3. GPS is now only on the internal rail or GPS port on the side of the board. RX and TX are the first two pins located near the white connector labeled GPS.
  4. Telemetry is now on the last two pins of the INPUT rail where it is written TELEM.
  5. If you use PPMSUM or SBUS you can take advantage of 4 more outputs on the input rail. So CH9 will be on PIN1 of the INPUTS, and CH12 will be on PIN 4.




8 comments on “Version 3.2 – with NuttX ROS
  1. Marc LE BRET says:


    I’m trying 3.2 with NuttX on my VR Brain 4.5. BootLoader is OK, Firmware install via Mission Planner is OK (v3.2rc4). Ppm sum input is not fine (Was with 3.1.5 and DFU upload mode). Had a try with sBus (direct) with jumper on 7@8 and Sbus input on 6, no go.

    My config: Vrbrain 4.5 int compass, internalGPS (white plug with 3DR Neo6), Futaba sBus receiver or FrskyTFR4 (8channels PPMsum-Ok with DFU 3.1.5 firmware)

    Please can you clarify how set up PPM sum or SBus (confusing info–do we need special adapter–ref vrBrain wiki–) what is the correct pin to hook it and jumper configuration? No PPM firmware in the Custom folder for VrBrain 4.5 (Int GPS, Int Compass).

    How to be sure to have the right firmware configuration (int Compass and GPS)?



    • Thanks for your feedback.
      We are currently updating all the wiki with the new layout, that has only slightly changed.
      PPMSUM is now on INPUT CH7 (the 7th pin from the left)
      SBUS still need physical inverter like explained here: and it is on INPUT CH6.
      There is no need to put jumpers anymore because now it is naively supported.

      As you found out, GPS is now bound on the internal rail (or GPS port on the side of the board) and telemetry is on the last two pins of the front rail where label TELEM.
      SER1 is no more usable.

      Let me know if everything works.
      Please take some time to register to the vrbrain list on google:!forum/vrbrain-dev so everybody can benefit of these explanations.

      • Marc LE BRET says:

        Setup with PPM Sum OK (8 channels only receiver), I have a sBus converter coming soon,



  2. […] 4.5 with micro SD card reader expansion board: or directly from Mission Planner if upgrading from previous 3.2 […]

  3. Verschoren Willy says:

    I am using ubrain on a 250 and 450 quad.(mentioned both for a small quad)
    Onfortunatly the 450 had a crash and some(+ and-) connectors are melt.
    I could repare but like to buy a new one for the 450.
    What is the main difference between the VR and micro brain to use on a larger (450) quad to rectify the price difference.


  4. Verschoren Willy says:

    I have a other question for a clubmember.
    He like to know if it is possible to use micro or v-brain in a glider to use RTL ( or Rally points ) to get to a more comfortable position.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: