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). 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 (the one I downloaded was

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

18 thoughts on “How to Flash BLHeli_S ESC Firmware

  1. 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.

  2. 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.

  3. 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)

  4. 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


Leave a Reply

Your email address will not be published. Required fields are marked *

Are you Robot? *

I don't look at blog comments very often (maybe once or twice a week), so if you have any questions related to multirotor please post it on this forum You're likely to get a response from me faster on there.