In a setup with Leonardo + A4988, I am planning on powering the VMOT of the A49988 out of the VIN pin of the Leonardo. I have read somewhere that VIN can be a pin where you supply the main voltage or draw the main voltage.
Is this wrong?
I want to use a single power source that powers the VMOT and the Leonardo, so by powering Leonardo through its built-in barrel jack and then getting power out of VIN to the VMOT I am accomplishing that.
You are correct. The VIN pin on the Arduino Leonardo can be used to supply voltage. You can find more information about that on the Arduino Leonardo page.
It sounds like you are still asking questions about the same setup, so I merged your other post with this longer thread.
I recommend still placing a capacitor across VMOT and GND for the A4988. Also, you might want to consider adding another decoupling capacitor close to the Leonardo for extra protection. In general, having extra capacitors like that in your system should not hurt anything.
Your question is not clear to me, but it sounds like you are trying to use the 5V pin of the Leonardo to power VDD on the A4988. That should be fine.
