Hi! After producing multiple different PCB designs of a board for controlling a stepper motor, I noticed something that I cannot explain.
The boards are in general powered through 12 volts, then a voltage regulator brings the voltage from 12 to 5 V and another one from 5 to 3.3 V. Stepper drivers and microcontroller use 3V3 logic. Moreover there is a USB port for communication with the microcontroller.
I noticed (with different drivers, such as drv8825 and tmc2208), that motors tend to be less noisy and more reliable as soon as the USB is connected. I noticed with the oscilloscope that noise is heavily reduced when I connect the board to computer through USB compared to only 12 V power supply (stable lab power supply, with big decoupling electrolytic caps).
Could it be that connecting the USB I'm creating a more robust ground connection and it reduces the ground bounce? (I have two ground planes and a separate one for insulating the driver ground, connected to the others in one point).
I'm not so experienced and I couldn't find relevant literature addressing the problem.
Spit out all the hypothesis/theories may spring to your mind, thank you very much
The boards are in general powered through 12 volts, then a voltage regulator brings the voltage from 12 to 5 V and another one from 5 to 3.3 V. Stepper drivers and microcontroller use 3V3 logic. Moreover there is a USB port for communication with the microcontroller.
I noticed (with different drivers, such as drv8825 and tmc2208), that motors tend to be less noisy and more reliable as soon as the USB is connected. I noticed with the oscilloscope that noise is heavily reduced when I connect the board to computer through USB compared to only 12 V power supply (stable lab power supply, with big decoupling electrolytic caps).
Could it be that connecting the USB I'm creating a more robust ground connection and it reduces the ground bounce? (I have two ground planes and a separate one for insulating the driver ground, connected to the others in one point).
I'm not so experienced and I couldn't find relevant literature addressing the problem.
Spit out all the hypothesis/theories may spring to your mind, thank you very much