I’m using a A-Star 32U4 with 12V connected to Vin to drive a stepper motor at constant speed via Accelstepper.h in addition to 5 LEDs through a transistor. Using a digital thermometer I’m recording temperatures of approx. 43 deg Celsius on/near the USB port. Is that going to cause me problems? The TMC2208 SilentStepStick board is around 30 deg C and the ATtiny85 chip at 28 deg C. The PCB (which has top/bottom GND planes) is around 29 deg C.
Just to clarify, is the A-Star 32U4 working normally despite the temperature or is it behaving oddly? I generally wouldn’t expect 43°C to cause a problem, but it does seem a little odd for the USB to be getting that hot. Could you clarify which version of the A-Star 32U4 you are using and post some pictures of your setup that show all of your connections?
To clarify, we have several products that have “A-Star 32U4” in the name, so it is not entirely clear which controller you are using. They are all pretty visually distinct (either from the form factor or color). Here are links to the specific variations we carry:
While your diagram is helpful and specifies the connections you are making, it does not always account for everything that could be causing problems (e.g. inadvertent shorts, excessively long wires, poor solder connections, environmental factors, misplaced/wrong connections), so some pictures of your actual setup are always helpful. Additionally, I would be able to identify which A-Star 32U4 product you are using.