How to Flash BLHeli_S ESC Firmware

Here I explain how to flash/update BLHeli_S firmware on your ESC using Cleanflight FC Pass-through.

At the moment BLHeli_S is only supported on a very limited number of ESC’s (as far as I know, the Aikon SEMF 30A, DYS XS20A and EMAX Lightening 35A). You should check out this guide about how to choose ESC.

They all come with BLHeli_S pre-flashed, so when you connect them to BLHeliSuite you should see that. Flashing with one-wire or FC pass-through should both work fine. Here I demonstrate how to update BLHeli_S on my new Aikon SEFM 30A ESC with cleanflight FC pass-through.

Hardware and Connection

  1. First of all, flash Betaflight on your FC in order to use the FC pass through feature
  2. Plug your ESC signal/ground cable into the FC motor output pins (I used PWM #1 here)
  3. Connect the FC to computer via USB cable, but do NOT connect to Cleanflight GUI
  4. Power on the ESC with LiPo, 3S, 4S doesn’t matter as long as rating allows

flash esc via flight controller naze32 aikon sefm 30a esc

Firmware and Software

5. Download the latest BLHeliSuite software from here (link in the section at the very bottom, read me)

6. Under “Select Ateml / Silabs Interface” in the menu, choose “SILABS BLHeli Bootloader (Cleanflight)” to use FC Passthrough to program/flash your ESC’s

7. Select the correct COM port of your FC, and press “read setup”. If nothing shows up you might need to press “check” as well.

how to flash blheli_s - select silabs blheli bootloader cleanflight fc pass through

8. The interface is different from the normal BLHeli with reduced options.

9. If you see “BLHeli_S Revision” number is below the latest version, then you need to update it. (The latest was 16.1 at the time)

how to flash blheli_s - read setup check button old 16.0 revision

10. Press “Flash BLHeli” and you will see a pop up window. firmware option should be filtered down to only 1 left, because it has BLHeli_S installed previously, and the system can detect what ESC this is connected.

11. Select this firmware, and click OK to flash.

how to flash blheli_s - click flash choose latest firmware version

After it’s done, you should see the Revision number updated.

how to flash blheli_s - finished flashing new version blheli_s firmware 16.1

35 thoughts on “How to Flash BLHeli_S ESC Firmware

  1. Quynn Bell

    I am kinda new to the drone community. I am currently trying to flash my Makerfire 35A BLHeli_S ESC’s. I cannot get BLHeli configurator to flash any other software besides J-H-20. I am able to load almost all versions of J-H-20. I also see other ESC types like G-H-30, but I cannot load any of these. Also, what do the different types and models mean? Does anyone know? There is little to no information online.

    My current set up is using the Makerfire 35A Esc’s, SP Racing F3 flight controller and Taranis Q X7 controller. My issue is that the motors do not spin up the same and sometimes reset mid flight. Anyone experience a similar problem? Also, the trottle response is almost none, once I give it one click of throttle the motors spool up to full speed and do not register a drop in throttle from the controller. Is this a software issue or a bad esc? I am willing to provide more information to anyone willing to help. Thanks.

  2. Luis

    I have a NiDiCi 30A “BLHeli_32” ESC and I am trying to flash the BLHeli_S firmware on it. The reason being is that my FC is a pixhawk 4 and it only takes analog input but the ESC I currently have uses digital input.
    Is there a way this can be accomplished?

  3. Richard L Doberstein

    I don’t think this is correct. You cannot flash Blheli_S esc’s with regular BlheliSuite. You will flash it with non S firmware. They have the same names. But it won’t say BLHeli_S anymore after you flash it. You have to use the BLHeli Chrome app, or use the portable version Found here

  4. Jack

    I have a problem about my esc. BLheli show firmware code of motor 1,2,3 are ESC A-H-25, 16.6 but motor 4 is ESC A-H-15, 16.6 and I can not Flash it to the same above. I wonder that I use the same ESC of Little Bee 30A-S ESC but it shows not the same firmware code. Can u help me solve this problem?, Thx

  5. George Birchenough

    Hiya. Hoping you can help. I have an application where I need to use a BLDC motor as a starter motor for an engine. I need the ESC to drive the motor immediately when power provided – no arming, beeping, no calibration. Would it be possible to modify the BLHeli code to achieve this? The engine control unit currently opens a relay for 3 seconds to power a brushed motor.

  6. Matyas Csiha

    Hi Oscar,

    I’ve got a Racerstar 4 in 1 ESC.

    Motor number one isn’t spinning right, even after I switched it out with another one the same thing happens.
    That’s why I think something is going on with the ESC. I flashed the firmware on all 4 and still the problem prevailed. Do you have any other ideas what the problem could be? Thank you

  7. Burak

    Hey Oscar, I just looked in these Hex files and they are all like H_L_xxx.hex , L_H_xxx.hex something. I am using Littlebee 20A Pro so what should i choose i dont know can you help me?

    1. Oscar Post author

      You shouldn’t need to choose, BLHeliSuite should detect what ESC you have and decide for you.
      If you are having trouble you can also try the BLHeli Configurator (Chrome App)

  8. Istvan Papp

    Hi Oscar,
    There is an Aikon 30A ESC

    How can I check which version?
    How to connect to Pc?

    I use CC3D Rev with openpilot software

  9. Vuk

    Hi Oscar,
    I have Emax 12A ESC based on BLHeli with NAZE 32 full version. When I connect it to BLHeli Suite and hit connect, the system recognize there are 4 escs but can’t read the type or BLheli firmware version ….. “ESC not found”.
    When I hit “check”……. ESC 1 ——-, ESC 2 ———— and so on.
    Do you have an idea why it doesn’t work?



  10. matt keenan

    1st … is it ok to use an emax 2204 2300kv motor with a (sold as ) hobbypower/ but is really a simonk 30a bec 5/2A dc 5.5v – 12.6v or can it be used on some Racestar BR 2205 ? i dont want to smoke em (esc or motor)!
    2nd …is it ok to mix motors like an emax and a racestar if both kv ratings are same ?
    finally ..if u have a pre configured known to work simonk 12a esc can you copy the setup on it and put it on all 4 esc so no need to manually setup and calibrate each one seperatly.
    thanks tech gods!! ;-D

    1. Oscar Post author

      1. make sure the motor/prop combination draws current under the ESC rating and you should be good to go.
      2. don’t mix motors, just the same motors.
      3. I don’t use SimonK ESC now, nobody does anymore i think :) so I don’t know !

  11. Mitch

    Hi, just wondering I’ve got aikon SEFM ESCs and running Kiss FC. I don’t want to flash my Kiss FC with betaflight, is there a way to connect the aikon ESCs to my PC to flash them without betaflight passthrough? I had an old AFRO esc usb programmer that I connected but everytime it got to the part to connect and I had to power up my ESC it would just sit there and not recognise my ESC now had power.

  12. William Mora

    As always, great information and easy to understand. My question is where do I find the information for my esc settings? I have Bl Heli S 30 amp esc with luminier 2206 2450kv motors. I copied settings but would like to make sure everything is correct. Thank you.

    1. Oscar Post author

      multishot is part of the BLHeli_S firmware, you don’t have to flash firmware again to use it, it already exisit as an option.

  13. Jean-Marie

    Thanks for this helpful info. Could I ask if ‘unsync pwm’ must be choose with these esc and if yes, which speed (16k,32k..?) (under betaflight configurator GUI) (I’m using seriouslypro Spf3 evo)

  14. Seven5555

    Which SimonK firmware should i use on my Multistar 20A V2 ESC With BLHeli and 4A LBEC? All of the info I have found is so old that it doesnt apply

    Thank you

    1. Oscar Post author

      you can use the new GUI (16) to configure older firmware ESC (14.4), but i don’t think you can do it the other way round


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