Need desperate help for the ESC calibration

Hello, there

I am struggling for about a month for the calibration of Graupner Brushless Control+T 100 opto ESC.

So far, I did following guidelines which have been posted in the google for last 4 weeks, but every method failed.

Pixhawk itself goes into the ESC calibration mode well, so that it shows big sound and color shifts continuously between blue and red. At the moment, I pushed the safety switch, but it outputs no sound. Also, at that point, I could not hear any sound from the ESCs.

I did try to calibrate ESCs by directly connecting to the receiver and it works great. Motor spins very well. However, whenever I try to connect through Pixhawk 2.1, the ESCs never enter into the calibration mode.

My heavy lift quadrotor system has specifications as listed in the below.

Is there anyone who have used Grapuner T 100 opto ESC? Any help and advice will be very appreciated.

Best regards,


Why do you insist on using the arducopter calibration, when calibration with the receiver works?
Looking at the manual you posted, the throttle needs to be at full for 10sec. It is been a while since I last used arducopter esc calibration, but if remember correctly, ardupilot does not wait 10secs to pull the throttle to minimum.
Why do you need a ppm encoder, when using a Graupner system, which puts out ppm as far as I know?
It is called SUMO in Graupner terminology. With my retired MX-20, I could set it through the telemetry menu. The receiver must be powered and bound, then you can set one channel (depends on the receiver model) to SUMO output and even more then 8 channels. I suggest you read through the manual again.

Dear Sebastian,

Thank you very much for your kind reply with fruitful advice. God bless you.
If I understand you correctly, the Graupner transmitter outputs PPM signal and so the PPM encoder would not be necessary.
If there is no PPM encoder, how do you connect between Pixhawk and receiver and so make them talk each other? There is a RCIN pin in the Pixhawk, so I think I should connect somehow the 8 channels of the receiver to the RCIN pin in the Pixhawk.

Best regards,


You can set up your Graupner receiver to output ppm on a channel. Then you needonly one cable between the receiver and the pixhawk. Here is a video showing how to do it with the MZ-24:

Dear Sebastian,

I do appreciate for the video manual.
I am currently figuring out which channel of the receiver should be connected which channel of the Pixhawk.


Dear life saver,

By connecting RCIN channel of pixhawk and channel 8 of the GR-24L, I am finally able to manage the communication between pixhawk and mz24 transmitter.

I can clearly see the movements of throttle and switches of transmitter in the mission planner.

However, there is still a problem on calibrating ESCs. I followed esc calibration manual (mov up the throttle, connect battery, disconnect battery, reconnect battery), but ended up with fails.

Is there any other suggestion?

Calibrating the ESCs with Arducopter is not mandatory. Just calibrate your ESCs with your receiver. As long as all of them are set to the same throttle range, there should be no problem.

Dear Sebastian,

I tried the ESC calibration with just using GR-24L receiver as shown in the following youtube video, but ended up with failure again.

In the video, firstly, I calibrated from motor 1 to motor 4 one by one.
Then, after I finished all individual ESC calibration using just the receiver, I connected ESCs to Pixhawk and tried to control speed which does not work.

What else can I try more??

Is this the first copter with ardudpilot you are building?
The video is not loading for me right now.
Did you complete all other calibration steps?
Did you ARM the pixhawk?
If there is a prearm failure, deactivate prearm checks for testing.
Be sure to reactivate them before your first flight!

This is the second time to build quadrotors.

I pre-built a small quadrotor with exactly same system setup (pixhawk 2.1, Graupner transmitter, power module, 30a ESC, and etc.) and tested outdoor flights very well using mission planner.

Then, I started to build this giant quadrotor weighing over 20 kg now, but am having a problem with the Graupner opto ESC.

Yes, I finished all the calibration steps (I will do it once more later), armed the Pixhawk using the safety switch, and can clearly see a solid red led. Also, I always unplug the battery and reactivate the Pixhawk after the calibration process.

I will order another brand’s ESC and test it whether it communicates with Pixhawk well.

Final update on this topic.

The Grapuner T 100 opto ESC cannot communicate with the Pixhawk, so do not waste of your time as what I did.

I switched to use T-motor 100A HV ESC and it works beautifully with the Pixhawk.