Nano racers: flash easily in 48 or 96 khz for more autonomy


You may have considered changing the ESC of your nano racer or your Tinywhoop brushless to 48 khz to gain autonomy. And then reading the method, you abstained. In this post, you will be able to follow a much simpler method, with fewer requirements.

48khz or 96khz?

It is possible to flash Tinywhoop ESCs in 96 khz. But switching to 96 khz instead of 48, is it really interesting? Might as well give the answer right away: the gain in autonomy is very low compared to 48 khz. On the Mobula6 that I tested, the 96 kHz mode even introduces parasitic micro-vibrations. On the Tinyhawk 2 that I am testing at the moment, on the other hand, the flight is perfect and remains flexible. It is therefore difficult to decide, the best is to try before adopting or rejecting. The good news is that you can go from 48 kHz to 96 to 24 kHz whenever you want.

In summary ?

On a nano racer, do not stay in 24 khz, switch to 48 khz, the gain in autonomy will be nice. You can possibly try the 96 khz, without guarantee of an improvement (compared to 48 khz). You can use the method described in the previous post (see here) to switch to 48 kHz. It's simple, but you need a rather painful prerequisite: having upgraded the nano racer to Betaflight version 4.1.1 (or more recent). If you are not very familiar with Betaflight settings, I do not recommend it. Know that there is much simpler! Above all, remember to remove the propellers before any intervention on the firmware of your nano racer and its ESCs, unless you are a fan of thinly sliced ​​fingers for a dinner aperitif...

The requirements?

It doesn't matter the version of Betaflight on your nano racer, as long as it's higher than 3.5.x. However, switching to 48 and 96 kHz only works with ESCs based on the efm8bb21 processor. How do you know if those on your device are? Download the tool BLheli Configurator, here. It is free, available for Windows PC, Mac OS X and Linux. On a Windows PC, you may need to install additional drivers, the links to which can be found on the home page once the software has been launched. Connect your nano racer via USB, with the battery plugged in and click on Connect, then Read Setup. If the ESC model contains an H in the middle of its name, such as OH-5, it is compatible. If it's an L, it's not. It could be that compatibility is added later (the competitor JESC is now, subject to having flashed Betaflight in version 4.1.1).

The file to flash?

Note the reference of your ESC when you do Read Setup in BLheli Configurator. In the case of Mobula6, it's OH-5. To flash in 48 khz (or in 24 khz if you want to go back), direction this archive from Github containing versions modified by JazzMaverick. Choose the most recent directory, 48k - it's 16.77 as of this writing. Next, find the version of the file that matches the version of your ESCs. For the Mobula6, it's O_H_5_48_REV16_77.HEX. Click on it and then on Raw. Copy-paste the entire data (there are more than 400 lines) into a text file and save it with the extension .hex For example oh-5-48-1677.hex

How to flash the ESC?

Make sure your nano racer's battery is fully charged. Although the flash of the ESCs does not last more than a minute, the battery must not let you down during the procedure. In BLheli Configurator, click on Flash All, then Select File Manually, and specify the configuration file with the extension .hex. The flashing operation starts on its own. Once all the ESCs are flashed, it's over. Disconnect the USB cable and battery, put the propellers back in place, reconnect the battery and take off!

And to try the 96 khz?

The 96 khz versions to flash can also be found on Github, modified by JazzMaverick, here. At the writing of this post, the most recent were 16.73. The procedure is the same as for the 48 khz: find the version for your ESC, save it with the .hex extension, flash it… And that's it! Do a few sight and FPV flights to check that the behavior is correct and that you don't get spurious vibrations. If so, you can revert to the 48khz version, and even the 24khz version if needed. Up to you !

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  1. @ JacquesB: Certainly if the ESC suppliers deliver them in 48 khz. If it's the integrators, it's probably more touchy since they would resell modified products.

  2. can we consider doing this manipulation on larger devices? Does it work on regular ESCs?

  3. @ Antoine LESAGE: The more you go up in size, the less the hack is relevant...
    The 48 khz was already possible with BLheli32, the “novelty” is to do it with BLheli_S.

  4. @Fred.. we get there at the 100kHz I was talking about, but as you said to Antoine, only a test will give, for lack of established theories, the good compromise?

  5. Tested on 2 2-inch drones at 48kHz, I am almost certain of the increase in autonomy. The behavior of the 2 quads remains as good or even less vibration for the cinewhoop when increasing the throttle (which previously was noticeable during HD viewing), than good.

  6. Hello confined people,

    @Fred @Mecatoche
    A question: my Eachine UK65 is in O_L_5, can I flash it with the O_L_5_48_REV16_8.HEX file available for a few days? How to know the dshot…?
    It would increase my autonomy for my domestic runs!
    The thank you box

  7. @ Fred, well those who know aren't there… I try again a little bit on the side of @ Mécatoche.
    Waiting for a possible response:
    – do I jeopardize the ESCs or motors of my UK65 if I try (even if it means going back if it doesn't work)?
    – how did you manage to kill your UK65, I'm on my 4th chassis change but it's still in great shape (except the camera which has a scratch on the lens) and I'm very happy with it have right now!!! What would you recommend as a model of the same size as a future replacement? The Mobula 6?
    Take care of yourself.

  8. Hi everyone, a big thank you for this tutorial, I just did the manipulation on my Trashcan 75 and my HX 100 and the result is stunning. An appreciable gain in flight time for these small models. You talk at the end of the article about a possibility to try the 48 and 96 kHz versions with the possibility of going back but I don't see any 96 to 48khz hex files (24 to 48 kHz, 48 to 96khz).
    What is the way to go back?

  9. Hello,
    FYI, in May 2021, the 48khz seems to have been withdrawn, it only offers 96kHZ. By following the link indicated in your tutorial for the file to flash, the latest version is 16.9. There are no more “_48” in the name of the .hex file on github. Still digging on this github page, I found this:
    has. Keep only PWM 96Khz for all small and large motors.
    b. Add ESC Feedforward. Acceleration and brake can be tuned by “PPM Min Throttle” in flash memory.
    Since motor response becomes fast, much lower BF FF is required.”

    PS: Thanks for the tutorial 🙂
    PS2: My freshly received UZ65 was already in basic ESC version 16.8

  10. Hello
    @fred @DUDU83
    I would like to switch my mobula 6 to 48 kHz but following the message from @DUDU83, which version should I take to have 48khz or do I have to switch to 96 kHz?

  11. @ Pitch: I admit that I didn't follow the evolutions with firmware 48>96. As my machines are in boxes until the end of December, I'm going to have a hard time trying out the new fws… If you don't want to worry, stay on 16.77 in 48 KHz…


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