BanlgeJS2 DFU version

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  • Hi all,
    I seem to have an issue with my DFU version when having a look at my firmware version. I recall trying to find the correct DFU to upload but didn't find much. Also not sure how to update the bootloader. I'd love any assistance with this and the ability to know what's actually happening. I noticed this before and after updating to firmware 2v20 earlier today.

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    • Screenshot from 2024-01-29 10-19-29.png
  • Are you updating from and not your own fork of the App Loader?

    Some folks had this issue a week or so ago atĀ­/393103/newest/ but I thought I'd fixed it in recent app loader changes.

    You can update the bootloader from that page - there should be a link after that text you screenshotted that says click here to update to DFU 2v20

    But at the end of the day, it doesn't really matter what the bootloader version is (especially if you're not an iOS user). It's probably best to leave it as-is.

  • nxdefiant just spotted what was wrong here - when I changed it to detect newer firmwares I accidentally stopped it detecting older ones. It's fixed now

  • Sorry, I closed this issue to soon when I got the first reply, so never got to end up replying. @Gordon, spot on with the DFU update! I was using the normal app loader ( Fortunatly I'm an Android user so no need to update I suppose but I did it anyway and it seemed to fix some other issues I was facing from prior to the update (2v18 to 2v19 but DFU stayed behind). I seemed to not be able to automatically connect to my phone back then but today it's been working fine since the FW and DFU update.

  • Sorry to kind of hijack the tread, but could you please clarify where you find the click here to update to DFU 2v20 link? I have never seen it in the Firmware Update app (neither on nor, in case it matters) and I don't know what I could be missing. Does it only appear in limited conditions?

    I only see this text:

    This tool allows you to update the firmware on Bangle.js 2 devices from within the App Loader.

    Your current firmware version is 2v20.69 and DFU is 2v16. The DFU (bootloader) rarely changes, so it does not have to be the same version as your main firmware.

    The currently available Espruino firmware releases are:

    Cutting Edge build:
    To update, click a link above and then click the 'Upload' button that appears.

    What is DFU?

    DFU stands for Device Firmware Update. This is the first bit of code that runs when Bangle.js starts, and it is able to update the Bangle.js firmware. Normally you would update firmware via this Firmware Updater app, but if for some reason Bangle.js will not boot, you can always use DFU to do the update manually. On DFU 2v19 and earlier, iOS devices could have issues updating firmware - 2v20 fixes this.

    DFU is itself a bootloader, but here we're calling it DFU to avoid confusion with the Bootloader app in the app loader (which prepares Bangle.js for running apps).


    Firmware updates via this tool work differently to the NRF Connect method mentioned on the Bangle.js 2 page. Firmware is uploaded to a file on the Bangle. Once complete the Bangle reboots and DFU copies the new firmware into internal Storage.

    In addition to the links above, you can upload a hex or zip file directly below. This file should be an .app_hex file, not the normal .hex (as that contains the DFU as well).

    DANGER! No verification is performed on uploaded ZIP or HEX files - you could potentially overwrite your DFU with the wrong binary and brick your Bangle.

    No file chosen

  • Hi - it should like this, but I spotted a problem with it (we were disabling updates for any firmware above 2v15 before as that was the only bootloader firmware we had available).

    I've just fixed it, and it'll be in the next update that gets pushed to in a few days

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    • Screenshot at 2024-01-30 16-22-26.png
  • Good to know! Thanks for taking the time to clarify this.

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BanlgeJS2 DFU version

Posted by Avatar for ramzy23 @ramzy23