What is your resolution of the oneshot125?

[Pluscrafter]

What's the resolution of the oneshot125 ? Is it 1us -> Resoution of 125(ca.7bit)? And is this accruate enought to control the motors?

[dridri]

It has indeed a resolution of 125. But there is currently a problem caused by the raspberry pi itself (and I'm afraid that it cannot be solved) that only one motor can run at a time in oneshot (or smaller timing protocol), using more than one will produce very unstable signal and the drone just cannot fly. I'm starting to think that using I²C ESCs can be a solution, or running motors control (and probably stabilization to reduce lag) on an STM32 besides of the rPi

[Pluscrafter]

Have you tried HardwarePwm like the in the pigpio library (not hardware timed pwm) then you have a greater resolution but unfortunally the raspi has only 2 hardware PWM channels with 4 output pins.

[dridri]

I already though about that, and the only solution I found is to use fast-switching transistors to alternatively send signals to motors. I will take a try on it on the next weeks

[Pluscrafter]

You could use a pwm/servo driver like the PCA968. It has a resolution of 4096 with 1khz. Then you have a resolution of 512. And what did you mean with the fast switching transistors(I'm a newbie in electronics :))

[dridri]

hmm actually using something like this http://www.ti.com/lit/ds/symlink/cd4066b-q1.pdf would be much easier. All the IN pins would be connected to Raspberry Pi's PWM output, CONTROL pins connected to 4 different GPIOs (one for each motor), then all OUT pins connected to the ESCs inputs.

Then we consecutively activate the switches to send different PWM signals to each motor