Which powers-up first?

Arduino + A4988 + stepper, driver calibrated, stepper connected. Separate power supplies:
Correct order to power up?
Arduino first?
Both at the same time?
Thank you!!!


If you want to be on the safe side then I would recommend powering the driver first, but in general it will probably be fine if you just power them up at the same time. The most important part of that is to avoid sending any control signals to devices that are not yet powered.

- Patrick

Thank you, Patrick! Now I can see the reasoning. So if the setup turns on both power sources at the same time, it would be wise to have a delay in the code before actual signals are sent to the driver.
I searched for this all over; didn’t find the answer. Your help is much appreciated.