I saw some people sugessting this (image bellow) in order to use both arduino USB and arduino adapter input making it easier to connect CNC machine that you are building.
Based on what I've read 12V should be fine for that input but seems like higher than that would be too much? I didn't look enought into the schematics but if there is some diode to protect from higher voltages that might be fine. Any comments?
The blue barrier terminal block is for motor power supply. The blue barrier terminal block only supplies power to the motor drivers. It is in no way connected to the Uno through the CNC shield. The motor power supply voltage can be between the minimum and maximum voltages for the stepper drivers installed. The most common are the A4988 (8V to 35V supply) and the DRV8825 (8.2V to 45V supply)
Do not connect the motor power supply to the Uno. That is just a bad idea. The built in 5V regulator on the Uno is not heat sinked and will supply a very limited amount of current before it overheats and shuts down if connected to 12V or more. If not using USB power, power the Uno with a 5V phone charger or use a buck converter to drop the motor supply voltage to 5V and connect that to the 5V pin on the Uno, bypassing the weak onboard 5V regulator.
If powering the Uno through the 5V pin, do not connect USB power at the same time. Use one or the other, never together.
Pololu has a good line to DC-DC voltage converters. Choose one that will handle your motor supply voltage, output regulated 5V and provide the current (at 5V) that your project requires.
Thanks for confirming my suspicions 
I guess I will just desolder that input and than superglue it on reverse so I can connect adapter to CNC shield and USB to arduino
I do not know what that means.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.
