FlightCtrl V2.2 / ACC

Upgrade FlightCtrl V2.1 -> V2.2

With this small adapter board the FlightCtrl V2.1 can be upgraded to version 2.2

With this update a more direct and precise altitude control is possible.

Needed for the upgrade:

The Update is only possible with the FC2.1 - older versions can not be updated

the upgrade

Small soldering work is nessecary.

  • solder tinning the three points on the FC
  • solder three short silver wires to these points:
    • C48 (Plus)
    • C36 (Minus)
    • C8 (Signal to the controller)

(Click for larger image)

Now it looks like this:

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For soldering, you should use a fine tip. It must be avoided that a shortcut to other components is produced by mistake.

After placing a small drop of glue on the yaw gyro sensor, put the ACC-board onto the three silver wires.
The sensor ACC-board is lowered onto the drop of glue, lightly pressed and soldered there:

http://gallery.mikrokopter.de/main.php?g2_view=core.DownloadItem&g2_itemId=134183&g2_serialNumber=1 http://gallery.mikrokopter.de/main.php?g2_view=core.DownloadItem&g2_itemId=134169&g2_serialNumber=1
(Click for larger image)

/!\ When soldering the Pins on the ACC-PCB, the lower end of the silver wire will become hot also. Make sure that the connection on the FC-side does not move and check it again after soldering.

The last step a solder bridge from the pad "J4" to "GND" is needed as solder-jumper:

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So the FC recognises that the new sensor is attached.

/!\ Warning: only put this bridge, if you really have attached the ACC sensor board.


After the work is done, the necessary software is loaded to the FC (minimum Version 0.90g). This can be downloaded here: en/Firmware-0.90

Check the function

Finally, the settings and the function need to be tested.

In the MikroKopter tool the hardware version should now appear as V2.2 (in the virtual display)
When the FlightCtrl is horizontal leveled, the AccZ value must show a level of 670-699.
(Note: The value must be less than 700, otherwise the old sensor is still active.)

This should look similar to this:

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  • The altitude control should be used in the mode "Vario-height".
  • A gas stick with built-in spring is advantageous because you don't have to search the zero-point.
  • The parameter "Hoover variation" must be set to 1 - the altitude control has full control of the gas then
  • The new position control will only work correct if you fly your copter (after each start) once over an altitude of 1,50 mtr. After this you can fly / hoover in every altitude you want.

First flight

  • start without altitude control first and hoover
  • Then activate the height control switch -> MK should now keep the height. The height can be moved with the gas stick

/!\ When a malfunction occurs, the height controller must be switched off immediately!



The accelerometer (ACC) on this adapter board works with a different principle of operation. Instead of Micromechanics the sensor operates with a thermal principle. Thus, the sensor is almost immune against the typical vibrations in the copter.

In the ACC sensor FC2.1 the offset of the Z value of the acceleration sensor drifts under vibrations. This only affects the vertical z-value. The two axes for nick and roll work great with the original sensor even with vibration.

The ACC adapter is connected via three wires to the FC (plus, minus and signal). Since the output of the old sensor (LIS344) has with 100k a very high impedance and the new has a low impendance, the outputs of the sensors can be directly conneted together. Only the signal of the new sensor will dominate.

Jumper J4

By connecting the J$ pin to GND , the FC detects that a new sensor is installed and the the new algorithms may be used.

Height control

The ACC Z value is fused into the altitude level and the climb/descent rate (Vario).

This makes the measurement of the altitude many times faster, which is beneficial to the entire height control. The MK can respond to fluctuations in the level already before an apparent height change occurred.


  • P (proportional) -> Makes the MK react on the effective height difference

  • D (differential) -> Makes the MK react on the sink / climb speed

  • ACC (Acceleration) -> Makes the MK respond to the direct vertical acceleration

  • Hoover variation -> if the value is set to 1 (100%), the height controls has access to the entire motor value (from MinGas to MaxGas)



  • Altitude P = 20
  • Baro D = 40
  • ACC-Z = 30
  • Hoover variation = 1 (100%)


  • Altitude P = 30
  • Baro D = 60
  • ACC-Z = 30
  • Hoover variation = 1 (100%)


  • Altitude P = 50
  • Baro D = 85
  • ACC-Z = 30
  • Hoover variation = 1 (100%)