ESC Firmware and Protocols Overview

There are several types of ESC protocol and ESC firmware available for quadcopter. In this article we will give a little history and explain the technical differences. Most importantly I want to try and clear up some of the confusion beginners experience from such a wide selection.

When I started in the hobby, connecting an ESC to a flight controller was pretty straight-forward. But now there is much more to consider: ESC settings, protocols, firmware etc. All these options can be confusing and overwhelming for someone just starting out in this hobby.

There is certainly a learning curve, I hope this guide can give you an helping hand through some of the difficult sections.

Check out this guide about how to choose ESC for mini quad.

I compiled the specification of all ESC’s for mini quad in this spreadsheet so you can compare them more closely.

ESC Firmware

ESC firmware is the software running on every ESC, which determines the ESC’s performance, which protocols are supported, and what configuration interface can be used. The firmware that an ESC can use is dependent on the hardware.

Here is a list of the different ESC firmware available for mini quad:

Two of the earliest options for open source ESC firmware were SimonK and BLHeli, and these firmware were used on the majority of ESC’s until around 2015. Since then BLHeli has taken over the market due its more user-friendly interface and consistent development.

Check out the differences between BLHeli and SimonK.

As ESC technology continues to evolve, newer BLHeli firmware is being written specifically for the advances in hardware.

In 2016, BLHeli_S, as an upgrade to the BLHeli firmware for the BusyBee processors.

In 2017, the 3rd generation BLHeli, BLHeli_32, was created to take full advantage of the additional processing power available from 32-bit processors we are beginning to see on newer ESC’s.

Nowadays, all ESC’s come with firmware pre-installed, most commonly BLHeli_S or BLHeli_32 depending on the hardware. Anyway this should be clearly stated in the product description.

These days you don’t normally need to worry about changing firmware. You don’t really have a choice after you have made your purchase. You do however, need to make sure the firmware is up to date for bug fixes and improvement.

For non-BLHeli ESC’s, they are most likely to come with and locked to their own factory firmware, such as the KISS ESC, Castle QuadPack, and the Gemfan Maverick ESC.

What are ESC protocols?

An ESC Protocols is the “language” that the flight controllers and ESC use to communicate, one of the most basic task is to tell how fast the motor should be spinning.

Here are all the ESC protocols available for a mini quad, and their respective signal width – the time it takes to send one data packet (click the links for more info):

ESC Protocol Speed

ESC Protocol Speed

Before 2015, there was only one ESC protocol, standard PWM, but as hardware improves, faster protocols become possible: Oneshot125, Oneshot42 and Multishot. These protocols are all analog signals similar to standard PWM, but much faster. These protocols are synced to the PID loop to reduce jitters, improve performance and reduce delay between stick inputs and the reaction of the craft.

DShot is the latest ESC protocol which is a digital signal. It’s the future of ESC protocol in my opinion because of its better reliability and performance, and the ability of sending not only motor speed, but specific commands to the ESC’s.

Hardware released after mid 2017 should support all the ESC protocols, apart from DShot1200 which is relatively new and is only compatible with some 32-bit ESC’s. Make sure to double check the specification when planning a new build.

I hope this guide gave you an overview of all the ESC software and protocols. Please don’t hesitate to leave me a question or comment.

17 thoughts on “ESC Firmware and Protocols Overview

  1. Brian Evans

    Hi Oscar
    How to flash updated firmware onto an ESC?
    I just used the default one which was 40-H and now my motors are acting strangely (spinning very fast at zero throttle).
    My ESC is Mamba 4-in1 F40 40A ESC.
    Any advice is greatly appreciated!

  2. Frantisek Dvorak

    Luis Inciarte

    I was trying to make Naze32 passthrough work for 2 days – and I made it to work.

    Way how I did it:
    – FC downgraded to BF 3.1.7
    – enabled softserial passthrough in BF configurator, enabled the softserial in ports tab
    – newest BLheli – silabs blheli bootloader (cleanflight)
    – done

    It is possible that with enabled softserial passthrough it will work even in newer BF

  3. John Gatza

    Hello Oscar – excellent writeup on escs and control protocol. Thank you.

    I’m building a quadcopter with Pixhawk 4 and I used airbot wraith 32 v2 escs since they seem to have the latest feature capability.

    Thinking Pixhawk 4 was also latest technology I figured this would work but I’m having trouble.

    I can program the eSC non pass through but cannot get the motors to move….using qgroundcontrol and mission planner. All else works and I’m disarmed. Any thoughts?

    Are these ESCs compatible with my Pixhawk 4? Thanks again.

  4. Luis Inciarte

    Helllo sir,

    I would like to have your suggestion about an issue that I am having to connect my ESCs using BLHeliSuite/BLHeliSuite32. The program is not reading my ESCs. Here is the info:

    ESC = Thriverline Acrotor BLHeli-32 ESC 30A 32Bit Brushless ESC Support 2-4S Dshot1200 (30A)
    FC = Readytosky Naze32 Rev6 Full Version loaded with Firmware CL V2.3.2
    Motors = EMAX RS2205S 2600KV Brushless Motor

    I just want to reverse 2 of the motors from CW to CCW.

    Thanks in advance

    1. Marcos Santana

      Hello Oscar

      Can I operate a ESC with BLHeli with Oneshot125 protocol with a simple PWM? I want the options that BLHeli suit have but I will use a controller that doesn´t have Oneshot125 protocol. (Is not a racing drone)

  5. Peter

    Hi Oscar. If I am trying to get a quadcopter-like design to work along with 4 servos, should I then use PWM so that there are no timer conflicts on my F3 flight controller?

  6. Sergio

    Hello Oscar,
    I’m curious if you may know what the control interface used in Hobbyking YEP 120A-HV ESC? I’ve purchased this controller from Hobbyking and it came without any documentation. The type of interface is also not mentioned in the description available for this controller. It is only noted that it has an optocoupler on its input. I woud greatly appreciate if you can share any information available on this unit.

    Thanks and Regards,

  7. Tyler

    How do I identify what protocol my esc are using? I’ve upgraded my FC to a Kiss. But I don’t know what protocol to use for the ESC mode.

    1. Oscar Post author

      You can set the protocol in your FC software, so you should be able to tell from there.
      As to what protocol your ESC can support, you have to look it up from the product specification.

  8. Sange

    I have a question that
    I just updated my Kingkong 12Amp BlHeli ESCs to the latest 14.9 firmware.
    Now will I be able to use the dshot or multishot or even oneshot42? Because I am using oneshot125 right now (I think, because I didn’t see much difference between oneshot enabled and disabled).

  9. Stefan Wilkens

    A new addition is showing up here, ProShot which sends hex data over three pulses with an added crc. The total package is shorter than dshot, longer pulses allow for caps to reduce noise.

    Support is being built in to beta flight

  10. Simon Kirby

    You can run SimonK at 64kHz if you’d like. Just change RCP_ALIAS_SHIFT such that it fits whatever timing you want. I tested it up to 256kHz PWM, and it worked.

    1. Saijin_Naib

      The SimonK? Nice to meet you, and thanks for your years of hard work!

      If I may bother you, I’m wondering if there is any value in updating the firmware/bootloader on the 3DR Solo ESCs to your latest SimonK firmware build and enabling OneShot125 on them, possibly with active braking (unless that will cause more of an electrical issue on the Solo!) I don’t think it will fix the ground lift/bounce problem the ESCs have, but I’m just curious what your take is on it (if you have one). 3DR forked your firmware back in 2015 or so, so I know you’d made fixes/advances/changes since then, and from what I’m reading, the 3DR FC firmware has a slew rate limiter in place to prevent the ground bounce to some level. I’m not sure if faster/more accurate/synced signaling would prevent the signal from getting interrupted. (I’m also not knowledgeable enough in this material to fully understand, just pulling info together).

      I’m planning on doing the flash as soon as I can figure out a harness to connect to the 3DR ESCs, but any advice/thoughts are always more than welcome!



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