[SOLVED] Crazyflie 2.0 doesn't respond to commands

[3zuli]

Hi guys, I am working with two Crazyflies 2.0. I used to fly them mainly through the android app, occasionally also through the PC client. I've previously made some changes to firmware (I added reading and logging of ADC values) and everything worked fine. Recently, I also developed a PCB for measuring the current flowing into the motors, more on that later.
Last time I flew them was on Monday, everything worked. On Thursday I wanted to fly again, but both crazyflies just stopped working properly. I can connect to them from the app (it looks like it's successfully connected), but the motors don't spin up when I move the sticks. *Sometimes* when I freshly (after a longer time) start the app and the CF, it will work on the first time, but as soon as I turn off and on the CF or the app and reconnect, it doesn't work. Since Monday I haven't made any changes to the firmware, neither updated the android app.
This happens regardless of which of the two crazyflies I connect to, I tried reinstalling the app and also tried a different device, without success. As a precaution I reflashed both CFs today, also without success. The PC client behaves similarly, I can connect, sometimes it works on the first try, but then stops. It looks like I can get some log data (battery voltage) and all the log and param TOCs are displayed. Sometimes however the Stabilizer graph shows totally corrupted data, the roll, pitch and yaw angles are changing randomly (and once I even got a sawtooth pattern on one of them).
On Thursday I started testing the first current sense PCB. I thought this could have been caused by an electrical error (which damaged/killed the CF) but I think that's unlikely, because the issue is the same on both CFs but I only attached the PCB to one of them.
One last thing that sometimes happens, is after pressing the power button, only the blue LED on M2 shines and nothing else happens.
Any ideas, what could have caused this and how to fix it?
Adam

[arnaud]

Hi,

Does the console display anything wrong and does the IMU calibrates (ie. if you start the Crazyflie while handling it the red LED should first blink slowly and when you put the Crazyflie on a stable surface the red LED blinks faster indicating that the IMU is calibrated).
Arnaud

[3zuli]

Hi, it seems like I have solved the problem. Turns out I just have to put the Crazyflie on a flat surface to let it calibrate itself. It was a bit strange, because I've been starting it handheld from the very beginning and it seemed to work most of the time, until this day. Nevermind.
What still keeps occasionally happening is after powerup, the blue M2 LED just shines and nothing else happens. Do you know what could be causing it? It's not a real issue because a restart always fixes it, I'm just curious to find out.

[arnaud]

Nice that your problem is solved .
For the startup issue it is a known bug that has been solved in the latest version of the firmware. It should not happen anymore if you upgrade your Crazyflie.