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Archive for December 28th, 2011

RoboBrrd + gEDA Brain Progress

Happy holidays everyone! Last week I worked on the schematic and board for RoboBrrd’s brain. There was also great research done about how to go about the interactive games for RoboBrrd.

Here is are some timelapse clips of this week in gEDA for RoboBrrd:


Watch on YouTube

I based the schematic off of the Diavolino and GNUduino arduino clones, because they are in gEDA too. Learning gEDA gets better with the more practice you have!

Screen Shot 2011-12-22 at 12.28.48 AM

The atmega328 symbol is from Matt Padina‘s TLC5940 knowledge base. It is so nice how it is organized and how the pins are labeled with everything!

The funny part about this schematic now is that I can see many small things that I dislike. For example, the amount of small capacitors. Are they really necessary on some of the power pins? I’m going to poke around at some of the other arduino clones to see how theirs is designed too. It’s kind of interesting, because there’s a boarduino on my desk beside me as I am typing it, and I just noticed it has an orange gumdrop-like component instead of a silver clock. I’ll research more into how that works!

One of the nice things about gEDA is that you can have multiple sheets! I use the input symbol with a custom netname to be able to ‘connect’ the pins from the first sheet to the second sheet. Here are the servo headers, on their own lonely sheet.

Screen Shot 2011-12-22 at 12.34.07 AM

For creating the pcb, in gschm2pcb I was stuck for DAYS on this issue with the footprints. I just couldn’t work it out. For some reason on both the Diavolino and the GNUduino, the headers use a standard footprint that I couldn’t find in my library.

Screen Shot 2011-12-24 at 1.33.01 AM

Finally, tonight I figured out a way to get the footprints! The ones on the Diavolino are nice, so to grab the footprint from the board and put it into a file, you can just do:

Edit > Copy selection to buffer (Ctrl-C)
Buffer > Save buffer elements to file
Save as a .fp > Done!

Since I was editing the schematic and the pcb had to be updated often, I found that the best way to go about this was to always remove the old .new.pcb file. If you don’t, I’ve had it happen where all of the parts get scrambled up.

This is what the board looks like right now.

Screen Shot 2011-12-27 at 11.10.54 PM

I’m not sure about the height of the board (the distance between the rows of headers). I need to figure out how to measure things in gEDA, that would be really handy.

The green rectangles are the screw terminals. They will only be on one side, because the board is going to be in the base on the right. In Impy RoboBrrd right now, it is really difficult to access the left side of the screw terminals because they are below the top face of the base. Plus, some of the wires stick out the side, which isn’t very good. Not to mention that the wires had to be longer, because it is longer to get to the other side of the board. And, they get tangled. Blech! As long as the board will be less than 12cm or so, it should be fine.

There is a large prototyping area on the board. It will be like a breadboard, hopefully this will help students! Also there is a mistake right now, the holes are vias when they should be pads. Have to fix that.

The blue rectangle will be an area to access all of the pins again. It will be handy. The brown rectangles will be some more pads that can be soldered to. The aqua rectangle is where the voltage regulator will eventually be able to plug in!

One of the things that I hope I’ll be able to do is silkscreen both sides of the board, because it will make it easier to see what pins are what when flipped over. I think the Arduino MEGA Protoshield does this, and it is extremely handy.

I’m not sure if I enjoy the placement of the voltage regulator near the back. This means that it would be at the front of the RoboBrrd, making the battery difficult to plug in. I have to think about this more, maybe it will be moved up to the front of the board, before the prototyping area.

Some cool things that I discovered this week that will be fun to play with in gEDA are:
SVG to PCB
PCB+GL

That wraps up week 2. The goal for this week mirrors that of last week, but to complete the progress that was started. FINISH THE BRAIN!

If anyone out there is trying to use gEDA to make Arduino related things, here are some of the resources that I found to be particularly helpful! And of course what better time to learn gEDA than now… there is even a gEDA badge!

Arduinos
http://www.evilmadscientist.com/article.php/diavolino
http://jeffrey.co.in/projects/gnuduino/
https://github.com/jeffreyantony/GNUduino

Shields
http://lowvoltagelabs.com/2010/11/16/arduino-shield-board-outline-in-geda-format/
http://lowvoltagelabs.com/products/videooverlayshield/
http://wiki.evilmadscience.com/ISP_Shield

More
http://sites.google.com/site/artcfox/demystifying-the-tlc5940
http://wiki.evilmadscience.com/Bulbdial
http://wiki.evilmadscience.com/Larson_Scanner
http://wiki.evilmadscience.com/Meggy_Jr_RGB
http://wiki.evilmadscience.com/Octolively

Random
http://wiblocks.luciani.org/remix/index.html
http://www.gedasymbols.org/user/russell_dill/cec.html