Thursday, January 14, 2016

Converting the Eachine Racer 250 to APM Controller

A while back I wrote about buying the Eachine Racer 250, which used a CC3d controller.  Well I got tired of trying to figure out this controller and decided to switch the controller over to an APM.  I used the Hobbyking Micro APM, but you can get the same hardware from Banggood.

This started out easily enough, but there were a few hurdles along the way.

Step 1 Disassemble the Eachine

Take the top deck and battery alignment plates off as shown in the figure 1.  Be careful when removing the power connector for the 5.8 GHz video transmitter as it can be easily damaged.  Use an old coffee cup to store the parts while you work on the rest of the project.

Figure 1

Step 2 Mount the Micro APM

The Micro APM will easily go into the CC3D mounting standoffs as shown in figure 2.  Note that you will have to remove one standoff that supports the battery alignment plate as it blocks the USB port.  Figure 3 shows the APM mounted from the top
Figure 2
Figure 3

Step 4 Wire Up the APM

Here is where it gets a little tricky.  The servo wiring from the APM to the receiver is done as per normal.  The website shows how it needs to be done.  This is easy.

Next, you need to supply power to the APM so you will need to make up a cable that goes from the Eachine 5V and ground power pads (green arrow Figure 4) to the power input connector of your APM (magenta arrow, Figure 4). You will need a 6 pin connector to attach to the APM.

Then, we come to the tricky part.  The connections to the motor speed controls are shown by the red arrow in Figure 4.  You have to make a new cable here.  The motor numbering IS NOT THE SAME for APM and CC3D.  The cable will need to be set up as follows:

APM            Eachine
5V                5V
Gnd              Gnd
Motor 1        Motor 2
Motor 2        Motor 4
Motor 3        Motor 1
Motor 4        Motor 3
Figure 4

Step 5 Reaasemble the Eachine

Now you can reassemble the battery alignment plate, top deck, and secure any loose wires.  You are ready to fly again after the usual ESC calibration, radio, compass, gyro calibration are done.

Figure 5 Reassembled Eachine Racer 250


  1. Excellent. Thank you for sharing. I plan to do this with my Eachine 250 when it arrives from china. :)

  2. Eachine 250 looks ok,but I know another racing drone:Akaso F250a Racing drone,maybe Akaso F250a is more professional.

  3. Ever since I read the review of this model I have been like "I have to add this racer to my drone fleet as soon a s possible" :) But now, after reading your text, I have a few questions. Why did you switch to APM? What are the downsides of the Eachine's flight controller? Did you notice improvement after instaling the APM? Oh, not to forget, here is the review that got me interested in the Eachine 250 racer

    1. I switched the controllers because I was very familiar with the setup and settings for APM and was struggling with setting up the CC3D. There also seemed to be problems in CC3D-land with two sets of software available due to a disagreement among developers leading to two teams doing two sets of software. Whether it was my familiarity or the better software/hardware of the APM, it worked better than the stock controller. Hope this helps.

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  5. Awesome sharing! Your five step approaches to convert an Eachine Racer 250 to APM Controller is useful. I have, in the meantime, read some reviews of similar drones like LG VR. The last one is really tricky. Caution must be required to wire up the APM