Power UNO from CNC shield

Hi,

I have my UNO/CNC shield setup and running, although there is a way to go figuring out coding for Limits switch and travel, but my issue here, surely, I must be able to power the Arduino from the 12v/2a supply to the CNC shield?

At present, the UNO is powered via USB, however, this will be a standalone unit I hope to operate 24/7, so I must be able to power the UNO from the shield... there is are 2 pins on the board labeled +5v and gnd which appear to be for a jumper perhaps... will this enable power to the UNO?

If not, how is it done without soldering wires to the underside of the UNO board?

What's the problem with soldering? YOu can put a wire on the cnc shield from +12V to Vin - but check te rating of your une before you power it up.

Really the better way is to use a 12V to 5V DC DC converter (buck converter) to go from 12V to the one of the 5V pins (and a ground pin) on the CNC shield. Powering through Vin or the power jack means that the Arduino and all peripherals that are on the 5V rail are powered by the onboard 5V regulator. The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down. The recommend max power dissipation for the regulator is 1 Watt. With 12V into the regulator the max current is about 140 mA (1W / (12V - 5V)). The Arduino uses around 50ma of that leaving less than 90mA (max) for everything else. I would use a buck converter to drop the 12V to 5V and connect that to the 5V and ground on the Arduino or CNC shield, bypassing the, weak, 5V regulator. Then the rated current of the DC DC converter is available on the 5V line.

Yes, I've used a buck converter before for similar purpose, but it's a last resort... surely, there must be a supply from the shield directly to the board as powere is available on the shield at the a4988 gnd and vdd pins which can be used to power the arduino when using a breadboard?

surely, there must be a supply from the shield directly to the board as powere is available on the shield at the a4988 gnd and vdd pins which can be used to power the arduino when using a breadboard?

Nope. Not on any of the CNC shields that I have used. The Vdd for the stepper driver is supplied by the Uno and the Uno is usually powered by USB. Check it. Connect the 12V and see if there is 5V available at the Vdd pins. I will be very surprised if it is.

My board has this 5v/gnd pair (see pic) just desperate for a jumper, or are they output power for arduino?