Motors not functioning when powering the through BigQuad deck

[RifRaf]

I'm currently using the BigQuad deck. What I've noticed is that when I use the 3.7v battery that came with the CF2, I'm able to get the motors to start working. The problem is that whenever I disconnect the 3.7 battery and connect the BigQuad deck's 5v pin at the ESC to the 5v pin at the BEC, I'm unable to get any rotation on any of the motors.
I'm confident that the ESCs are working fine because the ESC's confirmation beeps occur, so I guessed the 5v connection was the problem

Is it possible/safe for me to have both the 3.7v and the 5v connected at the same time?

[tobias]

That is a bit strange, I would expect it to be the other way around. As per the schematics the motor outputs are pulled high with a 1k resistor to 5V rail to get a 0-5V signal instead of the 0-3V the CF2 can output in a push-pull manner. So if there is no 5V then the motor signals will be floating.

Do you have a multimeter to check with? If so what does the 5V on the BQ-deck read when you have connected the battery only?

It is safe to have the battery connected and the 5V. Though the consumption can be up to 500mA when the battery is charging so make sure the BEC can provide that.

[RifRaf]

1. 3.7 battery connected (double checked the values for this one. I'll try again tomorrow. Perhaps I did something wrong for this section)
   
   • All of the 5v ports (including the one for the ESC, GPS, and CPPM) show 0.33v when nothing is connected
   • All the 5v and signal ports show 0.13v when any of the ESCs(unpowered) are connected.
   • All of the 5v and signal ports go up to 0.7v when thrust is applied
   • All of the 5v and signal ports go up to 1.0v when ESC(Powered) are connected
2. 11.1v battery connected
   • All 5v ports are at 5v
   • Signal ports are at 2.0v
   • I noticed that I was able to produce some thrust for a short duration, then it just stopped working again.
3. 3.7v and 11.1v battery connected
   • All 5v ports are at 5v
   • All Signal ports are at 2.0v
   • Motors are running smoothly

This has gotten me confused too. I'm not sure how the Crazyflie is able to power the BigQuad deck when it provides very little voltage. I'm afraid we may have damaged the BigQuad deck and thats the reason for the weird results.
I'll stick to connecting both the 3.7v and 11.1v battery connected for now since that looks like it's working fine.

[tobias]

Hmmm, that is a bit weird indeed. All the voltages are what I would expect them to be except that the motors should be running smoothly with option 2 as well. The signal ports read 2.0V because of the PWM. If you throttle up and down this would change a bit. I think the only way to debug this is to look at the motor signal with an oscilloscope, you don't happen to have access to one do you?