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Bootloader update



The bootloader (BL) is a small piece of software which is started as soon as the board is powered.

You should check the version on your on any OP board to make sure it is the most up-to-date version and upgrade the bootloader software if required.


Upgrading the BL can be tricky and if things go wrong you may brick your board and it will no longer start and operate normally.

How do I check the Bootloader version

The Bootloader version is shown when the board is in boot mode. You can enter boot mode by

  • using either the Halt option or,
  • by using Rescue. Both methods are explained below.

Either method will reveal the BL version on your board.


Halt Option

  • Connect your board via a USB to the GCS and open the Firmware workspace.
  • On the Firmware workspace, click Halt.

Once the board is halted, the BL version of the board is shown.

Click Boot to start your board again once you have noted your BL version.



Rescue Method

  • Do not connect your board to the GCS yet.
  • Click Rescue and plug your board via USB when prompted.

Click Rescue and when the prompt below appears, plug in the board via USB

When the board is connected, the BL version of the board is shown.

Once you have noted your BL version, click Boot to start your board again.

Bootloader versions

  • Version 1 - First BL version which is loaded onto all released CopterControl boards.
  • Version 2 - Safe boot capabilities are added to prevent the user from being locked out of the board due to a bad hardware configuration.
  • Version 3 - Different USB serial numbers between BL and firmware are specified. This helps Windows separate the 2 different functions of the board by making it think there are two different boards connected. Twitching servo movement during the board start has been eliminated.
  • Version 4 - Internal settings erase support, no more special firmware required. Just enter boot mode and click Erase Settings (CC/CC3D and OPLM)
  • Version 5 - Internal changes for better F4 boards support (Revo and OSD)


The BL for CopterControl (CC), CopterControl3D (CC3D), Revolution (Revo), OPLink mini (OPLM) and On Screen Display (OSD)

All OP boards are different and require the correct Bootloader to be installed, please ensure you download and use the correct version listed below.


CC & CC3D use following BL

Version 3 with GCS 12.10.2 and below

Version 4 with GCS 13.06.01 and above

BoardBootloader Update
CC - v3 (use with GCS 12.10.2)bu_coptercontrol-20120630_5a1efef3.opfw
CC3D - v3 (use with GCS 12.10.2)bu_CC3D-20120620_f44b9d3.opfw
CC - v4 (use with GCS 13.06.02 & above)CC-bootloader-updater/bu_cc.opfw
CC3D - v4 (use with GCS 13.06.02 & above)CC3D-bootloader-updater/bu_cc3d.opfw

If it is necessary to upload your BL, strictly follow these instructions:

Upgrade the Bootloader (BL) & Erase Settings


    • Download Bootloader (ie CC3D - BL4 or Revo - BL5)
    • Using the Firmware workspace in GCS, click Rescue and follow instructions.
    • After the board is detected, open the BootloaderUpdater (BU) file and flash it to your board
    • After the flashing is complete, press Boot and wait until the blue LED is on, then flashes, and finally goes off (normally ±15 seconds).
    • Wait 10 seconds more.
    • Disconnect the board from USB.
    • Click Rescue, connect board & click Erase Settings wait for erase to complete
    • Disconnect the board from USB.
    • Click AutoUpdate, connect the board to install firmware.


LED behavior

  • Slowly blinking blue LED 1hz interval: The board is booted and running the firmware, this is the normal behavior.

  • Bootloader mode.
    Slowly glowing of the blue LED, the green LED burns solid. The blue LED doesn't blink but fades in and out: The board is in BL mode.

  • If the blue LED is blinking continuously during a BL update then this indicates an error state. A wrong BL image may have been detected and the update isn't performed.

Step by step videos

Forum member, Goobs, has an instructional video showing how to check what version bootloader you currently have on your OpenPilot boards. This is the first step you will need to do so that you can work out whether you need to update the bootloader or not.


fredz69 made an excellent step by step video which guides you through the complete bootloader update process.


Although this tutorial shows upgrading to version 3 on a CC3D board, it is the exact same process to upgrade all boards to all versions of the bootloader firmware.

Note: The process has slightly changed to when this video was completed, please use steps above



 What's the difference between Firmware, Bootloader (BL) and BootloaderUpdater (BU)?

The Firmware (FW) is the application to be loaded by the Bootloader after the board has been powered. The Firmware is regularly updated and newer Firmware contains several new features and bug fixes. You need a matching Firmware and GCS version to configure your board,

The Bootloader (BL) is a small piece of software which is started as soon as the board is powered. Every board is loaded with a bootloader and is normally not upgraded by the user.

The BootloaderUpdater (BU) is an application which replaces the old Bootloader in the board (it contains the new actual Bootloader inside). The BootloaderUpdater is a smart trick to use the internal (old) Bootloader to load a special BootloaderUpdater Firmware which when started will erase and write the new Bootloader image on the board. (The new Bootloader itself is inside of this BootloaderUpdater application). This step is required because the Bootloader in the flash memory can't erase and rewrite itself in place.

 The Bootloader version isn't updated after the update.

There is a built in check that prevents the user to update the BL with an incompatible version. Most probably the wrong BL version has been selected. If you have a continuously blinking blue led during the upgrade process, this is the indication that the updater is in an error state. Reboot the board and repeat the process using the correct BU.

 How can I build the bootloader for CopterControl instead of CC3D?

The BU image can (currently) only carry a single BL image. Recent BU carries the CC3D BL by default. If you want to build your own BL for CC, use the following commands.

For more detailed information, see OPReview-205.

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