What’s this 4k/4k Mode And MultiShot?

If you haven’t tried 4k/4k with multishot yet, or something even faster, DUDE you are missing out big time. Go upgrade your favorite rig right now! I’ll get into details, but generally speaking the improvement in responsiveness is similar to the improvement pilots feel when upgrading from PPM to SBus. Yes, it’s that good! After upgrading, I immediately felt my comfort zone had expanded and that I was willing to go faster and execute exit/save maneuvers much later. Other friends who have recently tried these upgrades have expressed similar opinions. So please, don’t be afraid to upgrade with these new software settings, you will fly better with less latency.

What are these strange new things?

Multishot – a new ESC protocol that is an order of magnitude faster than the original OneShot.

You can download Multishot here, thank you RS2k! https://github.com/rs2k/raceflight/wiki. Once you have dowloaded the .hex files, flash your ESCs through BL Heli Suite and select “custom” or “other” for the firmware file. I’ve flashed this firmware on LittleBee20s, LittlBee30s, and UBad30s.

4k / 4k Mode – The first number describes your flight controller’s looptime. The second number describes refresh rate of the signal that is being sent from the flight controller to your motor speed controllers. It is possible to run both of these values faster than 4k/4k mode, if you’re running a Dodo or similar F3 processor 4k is the limit. If you’re running an F3 flight controller that uses the SPI bus like the Lumenier Lux, then you can run up to 8k. The motor refresh rate is limited by the processor that is on the ESCs. As I write this, the F390 what everyone is moving toward to get the best performance. DYS XM20, XM30, LittleBee30, and UBad30 ESCs all use this chip. The F390 are fast and can support 4k or faster.

LB20s and other ESCs unfortunately use the slower, previous generation F330 processor. I have it’s recommended to run 4k/2k mode on the older F330 ESCs. However, I’m mean to my electronics and tested 4k/4k mode today with a Dodo and LittleBee20s. I flew five or six packs and had no issues. My opinion is, go for it!

To setup 4k/4k mode you simply need to make the following changes:
1. Upgrade to Betaflight 2.6 or later. Get it here (thank you Boris!): https://github.com/borisbstyle/betaflight/releases/
2. Change looptime to 250 in the Cleanflight settings menu
3. Enter CLI, “set use_multishot=on” or “set use_multishot=yes”
4. In CLI type, “set pid_process_denom = 1”

PID Process Denom is a variable that sets your motor refresh rate. The equation that is used is, motor rate = looptime_rate / pid_process_denom. Since you set your looptime to 250 micro seconds (4000 hz), motor rate is also 4k when PID process denom=1.

I hope this article helps you try out the latest stuff!! Here’s my video from a fun session today where I tried out some other new moves with my Speed Addict 210. Please enjoy =)

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5 thoughts on “What’s this 4k/4k Mode And MultiShot?

  1. David

    Thanks for this tip and all your great help/inspiration in your blog and videos. One question, do you still enable OneShot125 in Betaflight or do you turn it off since you activated Multishot? Wasn’t clear about that so would be good if you can confirm. Thanks again!

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    1. Hey David, you just need to enter the CLI command. You can leave the box checked for “enable oneshot125”. As long as your ESCs spin up and you can fly, multishot is working properly. If you are using oneshot125, the ESCs will not arm.

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  2. Hi there, great write up! I could be totally wrong but I think the motor rate calculation is actually: motor rate = looptime_rate * pid_process_denom

    If it were divided by then how could you get 2Khz on motor rate with a looptime of 250 when the value range allowed is only 1-8?

    Is the 4Khz motor rate holding up on the regular LB20A?

    Thank you!!

    Like

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