A-Star 32U4 Mini SV

Using 32U4 to control three DRV8825 Stepper motor drivers. Was checking input current while actuating motors. The 32U4 stopped. Initially PIN 4 stopped working and then the whole controller stopped. See image of burnt pin on IC. Would not having a back driving capacitor have anything to do with it?


I am sorry you are having problems with your A-Star; it looks like the regulator is damaged. Can you post some pictures of your setup showing all of your connections? Can you tell us the rated voltage and stall current of your motor?


SchematicControllerboard.pdf (52.7 KB)

Rated Voltage of Motor 24VDC
Stall Current is 1.4A
Power Supply: NDR-480-24 (Mean Well)

Motor: Lin Engineering 5718L-01S-33RO

Thank you for posting that wiring diagram. A likely cause of damage to the regulator is a spike on the input voltage from the motor and driver part of the circuit. Your wiring diagram does not show the large electrolytic capacitors we recommend across VMOT and GND on the driver. Do you have them in your system? If not, adding them could help with voltage spikes. A similar capacitor across BAT+ and BAT- close to the A-Star could also provide some additional protection for it.

You mentioned checking the input current while actuating motors when you first noticed some damage, could the motors have become disconnected during that process? Disconnecting a stepper motor while it is powered could cause a voltage spike.


Thank you Derrill.
We saw the diagram for the electrolytic capacitors after we damaged the board.
How would you recommend sizing the capacitor?
We were looking at 180microF at 50V (Using the 24V motors)

Those capacitors seem fine.