Attaching and Powering an RPi Directly on the Shapeoko 3

Assembly questions and answers for the Shapeoko 3 CNC Mill
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mankyd
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Attaching and Powering an RPi Directly on the Shapeoko 3

Post by mankyd » Wed May 20, 2015 7:51 pm

I'd like to use http://chilipeppr.com/ to send gcode to my Shapeoko 3. I've got usb wifi plugged into a Raspberry Pi to act as the receiver.

Is it possible to power the RPi directly off the Carbide board or power supply? I'd love to avoid running extra cables all over the place. Ideally, I'll attach the RPi right next to the controller board with a short usb cable between them.
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mankyd
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Re: Attaching and Powering an RPi Directly on the Shapeoko 3

Post by mankyd » Wed May 20, 2015 8:55 pm

Looking closely at a high res image, I see both "grnd_5V" and "5V_data_clock_grnd" in the upper left: http://timf.anansi-web.com/images/misc/carbide3d.jpg

Anyone know if I can wire into either of those? Is the second one usb, or is it something else entirely?
Shapeoko 3 #147
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cvoinescu
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Re: Attaching and Powering an RPi Directly on the Shapeoko 3

Post by cvoinescu » Wed May 20, 2015 11:40 pm

The 4-pin connector is not USB (USB does not have data and clock as separate pins). I seriously doubt the voltage regulator on the Carbide Motion board can supply enough current for a Raspberry Pi. It looks like an ordinary 7805 with no special cooling provisions, so maybe you can get 500 mA out of it, but not much more -- and that includes what the board itself needs.

In short, you need a separate 5 V supply for the Raspberry Pi.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

rtlflatt
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Re: Attaching and Powering an RPi Directly on the Shapeoko 3

Post by rtlflatt » Thu May 21, 2015 2:15 am

With a regulated DC step down circuit we could use the 24v PSU couldn't we? I think I remember this being discussed before but I forget what was determined.
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cvoinescu
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Re: Attaching and Powering an RPi Directly on the Shapeoko 3

Post by cvoinescu » Thu May 21, 2015 2:25 am

You could. Check the docs for your model of Raspberry Pi to see how much current it needs, to make sure your DC-DC converter can supply that much.
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veng1
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Re: Attaching and Powering an RPi Directly on the Shapeoko 3

Post by veng1 » Thu May 21, 2015 2:14 pm

A 1.2A power supply is recommended for the PI although it can, perhaps, use less.

https://www.raspberrypi.org/documentati ... /README.md

If you are into building things yourself then a 7805 equivalent switching regulator module might work well. The ones I'm familiar with are through hole and both the Carbide board and the Pi use SMT regulators so it will have to be external:

http://www.mouser.com/ds/2/281/oki-78sr-56393.pdf

I've designed and built something similar in the past and can confirm that at Mouser's price it is not worth the trouble. Be sure to use a low ESR cap on the input. It will work up to 36V and put out 1.5A. If there are analog features on the PI that you are going to use, it probably will need a cap on the output too. But for just a camera, I'd guess not.

mankyd
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Re: Attaching and Powering an RPi Directly on the Shapeoko 3

Post by mankyd » Thu May 21, 2015 3:00 pm

Spoke with some folks at work. After some searching, I found this: http://www.amazon.com/gp/product/B00IWO ... RV4S4C32VE

I'm going to give it a try and will report back.
Shapeoko 3 #147
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Touch Plate
Hall Effect Limit Switches in the Works

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rodcar125
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Re: Attaching and Powering an RPi Directly on the Shapeoko 3

Post by rodcar125 » Fri May 22, 2015 5:04 am

Hi mankyd,

I'll be pursuing the same approach as you using a RPi with wifi dongle attached, I think this is the way to go.

From the converter/regulator you posted, where do you plan to get the juice from? Since the upper left connectionof the board is not an option could it be possible to attach the regulator at the bottom right connectors? The ones labeled PWR SW and PWR1 which are marked to be 24... Are those delivering power? I can't test it since I haven't received mine ):


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