Mikrokopter UAV are very common in Germany. They use their own Brushless ESCs, controlled with i2c by their own Flightcontrol.

From now on, it is easy possible, to convert a Mikrokopter UAV into a fully featured ArduCopter with a Pixhawk or PX4 only by replacing the FlightControl&NaviControl.

The i2c bus from the BL-Ctrl's have to be connected to the external i2c bus of Pixhawk or PX4.
Then follow these steps to turn on support for them:

Re-enabling the Mikrokopter I2C ESC Support for FMUv1 and FMUv2 (Pixhawk).
Mikrokopter ESCs have to be connected I2C Bus on Pixhawk/FMU.

Arducopter Mode:
To enable mkblctrl startup add a /fs/microsd/APM/mkblctrl file
In this configuration the ESCs must be ordered in the same order as the ArduCopter is numbering them.
In this Mode all Frametypes of ArduCopter are supported.

Mikrokopter Mode:
To enable Mikrokopter native Frame Addressing (Order) support:
For X Type Frame add:

For + Type Frame add:

With Mikrokopter Frame Addressing, it is very easy to convert a Mikrokopter to ArduCopter. Just replacing
the Flight-CTRL against a Pixhawk, and your are done after initial Setup.

In Mikrokopter Mode there are only X and + Type Quadro, Hexa and Octo Frames Supported.
In Mission Planner the right Frame have to be set.

There can be only one startup File on the SDCard (mkblctrl, mkblctrl_x, mkblctrl_+)

I am using my PX4/Pixhawk nearly one year with ArduCopter and PX4-Flightstack without any problems. It is really working rock solid.




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  • Excellent, thank you. As a user of MK and Pixhawk this is very useful information. I previously saw information connected to this on the PX4 website but this clarifies the simple procedure.

    The alternative switch, that is to use third party ESCs with an MK stack now seems to be limited to firmwares earlier than FW2_02, which is unfortunate for those of us trying to build longer duration models with the MK stack.

  • Marco, glad to hear your MK's are performing as they shoud. I respect the work of Mikrokopter, they were one of the first in this sector, without them many things wouldnt be that good as they are now.

    I absolutely agree with you, if your copter is working good, no need to change anything, but just keep this bottleneck in mind and be prepared. For a new build, I would choose other ESC's as well.

  • Hi Marc,

    you are right. If one device on the bus blocks it, the whole system comes down. But luckily i had never this situation. All my past MK's and my current Pixhawk's are rock solid with these ESCs.
    But for building a new copter, i don't recommend these sort of esc.

  • Hi Don,

    for me there is no reason to switch back to MK.

  • Nice to see the capabilities growing, although i find the Mk i2c a horrible idea regarding safety considerations. If one device in the bus fails, you are done. A couple of copters came down this way.
  • Hi Marco,

    How does the performance of the Pixhawk compared to the MK?


  • Hi Arif,

    the. i2c bus is a multi device bus. You can connect multiple devices to the bus. There is a i2c splitter with a 4pin cable in your pixhawk box. This can be used to connect multiple devices to the bus.
    In my case i have the GPS/Compass combo from 3DR connected to my Pixhawk too. It is working great in combination with the BL-Ctrl esc's.

  • hi marco,

    what if the i2c is being used by compass.. the only i2c on pixhawk that i can see is next to ADC 6.6V.

  • Hi Roberto,

    it is only output mode, instead of pwm esc's.
    The i2c is open drain, and already pulled high to 3.3v by the pixhawk. There is no need to have a level-shifter with the BL-Ctrls. You can connect them directly to the Pixhawk/PX4.

  • Moderator

    Hi Marco,

    i support yet at the begin of arducopter project 3 years ago :) I'm happy that now is available again ... but it's available also advanced feature or only possible use as pwm ? So only in output mode ?  

    Other question is about hardware interface do you need a level converter 3.3v to 5.v i2c or is compatible to 3.3v ,too ? 


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