MrOnion's OnionBoard - GP IO/Power PCB (requires CPU board)

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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by Fred »

Never didn't work for me.
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MrOnion
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by MrOnion »

Ok, 5 pcs of onionboards arrived on friday but are still stuck in customs so will get them on mon/tue.

First batch is small just to make sure the board is ok. I will keep one or two for myself and send two to Fred. So basically there is an extra one if someone is brave enough to try it ;). AND possess some sort of separate VR conditioner, preferrably the BrickRPM.

The first version has the headers to match the pinout of the BrickRPM board so it depends on it. As you may know Fred is pretty busy at the moment and there is no date set when new bricks will be available. Fred kindly offered me the change to make more bricks myself if I decide to order more onions to keep things rolling.

As this whole onionboard thing is basically a replacement for vero/other diy boards the demand is not huge. And if someone is getting their hands dirty on freeems from scratch I definately recommend to get a Jaguar board over this setup as it's more thoroughly tested! Of course if someone is planning to play around with a different CPU then this might come in handy, but this is out of the scope of freeems.

So, if there are people interested in this board I can easily order more and this might create the demand to get more brickrpm boards on the side. Or I can include the footprints for the conditioner in the onionboard instead of the headers and order more of that version.

The latter seems like a better idea from my point of view as I don't need to populate the boards with parts as I need to do if I ship bricks. I also feel that I don't have the equipment to properly create and test the bricks and therefore not wanting to stain the brick brand :).

I already made a separate branch for the board with it's own VR conditioner. It's a quick draft based on Jaguar:

EDIT: Changed correct component values to schem and moved the chip a bit to the left on board.

Image
Image

If someone spots a flaw in the design give me a warning and Fred, I hope you are not heartbroken about this change ;)

And I almost forgot to mention I released the project in github:
https://github.com/MrOnion/Onionboard

The schematic is also cleaned up for easier review. Need to include PDFs and a BOM later. The VR circuit is not in github yet.
Last edited by MrOnion on Sun Oct 20, 2013 3:04 pm, edited 1 time in total.
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by Fred »

Neat :-) No, I don't feel rejected :-p
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MrOnion
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by MrOnion »

Quick proof that they actually exist ;). Silkscreen is shit, but thats what you get when using a skinny and tiny font :(.

Also f**ked up the heatsink placement but that can be modified. The molex connector holes are the right size but the legs on my connector are squared so they wont fit without a fight... But, all in all boards look ok. I'm happy.

Image

Image

I'll try to assemble one during the weekend...
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by Fred »

Awesome! Mind if I publish those here and there? :-)
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by MrOnion »

Sure, go right ahead.
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by ivan141 »

What's the idea behind those clustered via's? Haven't seen them put in traces before.
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by Fred »

Current flows up through them, and potentially quite a lot of it.
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by MrOnion »

Yep, that's the point. I read an article once where there was some info about should you use many small vias over one large. The conclusion was that it didn't make too much of a difference.

I have seen these used in several other boards with H-bridge drivers, etc. Chips that need to sink high currents.

Edit:

In here it says:
"When vias are used to connect PCB layers in the high current loop, multiple vias should be used to minimize via impedance."
Last edited by MrOnion on Wed Oct 23, 2013 11:17 am, edited 1 time in total.
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Re: MrOnion's OnionBoard - GP IO/Power PCB (requires CPU boa

Post by Fred »

It helps get the heat out a bit, too :-)
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