USB Serial Communication to Astar w/o Vbus from Computer

Support A-Star and Orangutan
1

Hello,

I am currently using an Astar mini sv to control a multi axis stepper driven test fixture. I have the stepper drivers and the Astar powered from a 24V supply going to Batt + and -. I will have a computer (NUC) in close proximity to log output values over serial communication from the Astar. I would like to have the Astar not be powered even though the usb cable to the computer will be connected. Could I connect a 5V line from the Astar back to the vbus and isolate the vbus line from the computer usb? I attempted to use a usb cable with the vbus line disconnected, but the computer did not recognize a com port connected. I would also like the ability to continue to use the computer to program the Astar over the connected usb cable. Is this possible?

Thanks in advance

2

Hello.

Why do you want to remove the VBUS connection between your A-Star and computer? If you do not already know, there is a power selection circuit on the A-Stars that allows both USB and VIN to be connected at the same time. The power selection circuit is configured to draw from VIN unless the regulator output falls below ~4.5V. You can find that information under the “Power” heading in the “A-Star 32U4 Mini” section of the A-Star 32U4 User’s Guide.

- Amanda