Speed Controller and Navio2 Protocol Issue

hello everyone. I recently purchased the navio2 and Racerstar RS20A BLheli_S 4-in-1 ESC. I can’t get the navio2 to use either one of the oneshot protocols. And the ESC doesn’t support PWM. What should I do?


There is a bug somewhere with 3.6x arducopter preventing Oneshot to work with Navio2.

Oneshot 125 was fine on my Navio2 with Arducopter 3.5.5

If you have the latest Navio2 image (2019) you can use Emlidtool to choose Arducopter 3.5. It is the arducopter 3.5.x (maybe 5 or more) from Oct 3, 2018.


How do I rollback the version of arducopter to 3.5.5?

BTW, thank you for your quick response.

Connect with SSH to your card, run Emlidtool ardupilot, stop arducopter, quit emlidtool then rerun emlidtool (without rebooting the card). You will have access to the config menu.


It wont let me select anything but 3.6 for the “choose your version”

We have to check. I have emlid-raspbian-20190227.img copied to my Navio2 SDCard.

Enter the command cd /opt/ardupilot/navio2

then ls -l

The result:


If different, be sure to have the right emlid image installed.

When running Emlidtool you should have access to 3.5 version



Thanks I will give that a try. However, I was testing out the Servo.py file from emlid’s github repo and the motors were behaving erratically.

this repo: https://github.com/emlid/Navio2

and this file:

import sys
import time

import navio.pwm
import navio.util


SERVO_MIN = 1.250 #ms
SERVO_MAX = 1.750 #ms

with navio.pwm.PWM(PWM_OUTPUT) as pwm:

while (True):

Sorry but I mislead you.

I was running updated version of 2018-05-25 emlid image.

2019-09-27 image is missing the 3.5 directory.


I hope you see my latest msg. 3.5 directory is missing from 20190227 navio image.

I was working with the updated 20180525 version. If you have the old image on your computer you can flash it on the SDcard and update upgrade to the latest version. Arducopter 3.5.5 will be available to use with Oneshot125.


Where can I download the older images?

Hi @Lucullus,

You can download the previous image by following this link.

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