Propeller Proto Artwork

softex

Hello all,

I'm going to take a whack at building a small SMT prop board to do video. I've done a few through-hole designs, but to make sure I don't get too far off-base I was wondering if there has been posted anywhere an example of some Propeller PCB artwork (not schematics) featuring surface mount components. The prop proto design would probably be all I need to confirm how to do this - I have the board, but its hard to see into the substrate. I'm particularly interested in finding out how one deals with routing all the traces on the top surface only (presumably) and using the bottom layer only for one big ground plane(?) - and not using any vias(?). I've searched the forums. but nothing seems to come up - just schematics. Have I missed something somewhere?

-Dave

CannibalRobotics

I have the objects for the prop 44 QFP that works with ExpressPCB. Both schematic and PCB artwork.
Helps?
Jim-

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softex

Thanks Jim, I was actually looking for a good example of how to lay out the QFP with the EEPROM, crystal, and a few resistors. Nothing fancy, just a good template to get me started. I'm using Eagle so component libraries are no problem. I seem to recall seeing the PCB artwork for the proto board on the parallax site some time ago, but I may be mistaken. I suppose, being a prototyping board, the layout could (should?) be available?

-D

Leon

Here's a design of mine:

www.leonheller.com/Propeller/Module.GIF

Leon

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Carl Hayes

It's fruitless to try to do everything on the top layer. Use vias to get to the bottom, and the SMT devices actually are easier to lay out because you don't have to dodge the device's pads, which don't clutter the bottom.

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· -- Carl, nn5i@arrl.net

softex

Thanks Leon. I was just starting to realize (after looking closely at some boards) that vias are still OK for SMD. I generally try to avoid them as much as possible. At first, I guess I must have been looking at some RF products or something, with huge ground planes and somehow got the notion that surface-mount meant mostly one surface(?!). Do you suppose it would be good practice to put vias right under the feet of an eeprom, say, to take GND instantly to the bottom layer? Or am I being a little too anal about all this.

-D

... and thanks Carl - I caught your post just after I submitted this.

Post Edited (softex) : 2/17/2009 12:39:07 AM GMT

CannibalRobotics

Dave,
I'm going to send you some artwork and schematics of a project I'm about to reveal to the rest of the prop forum. I've been working with RF and the prop and this project is the culmination of about 6 revisions and allot of discussions between me and the RF vendor.
I'll post it here in a little later. (I've got to get it off of my website and make a correction that I discovered today.

Jim-

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CannibalRobotics

OK,
Here is the circuit and artwork layout for two boards. It uses the Linx RF LT series transciever module. The RF board has it's own power supply in the three AAA batteries. It had to be put on it's own board as proximity to the CPU was just too noisey. The other is the CPU board. The CPU board carries the compass, excelerometer, A to D converter and a video camera multiplexor.·You'll notice that the RF board·traces are·pretty much completely on the top side of the board and protected from the CPU by the ground plane. The CPU board also has a ground plane and the two boards sit in the case with the two ground planes parallel to one another. They are connected via the 14 pin connectors.
In a couple of days I'll be posting some photos of the finished product.
Let me know if it helps.
Jim-


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softex

Sounds good, I'll take a look when I get my PC back and load ExpressPCB. Right now I'm on my Mac with Eagle.

CannibalRobotics

Go look at my post on the Rover controller. It ha a video multiplexor on it.
Jim-

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