Hardware Mode: Raspberry Pi Case & Solder Spool Stand.
June 24, 2012 7 Comments
In a previous post, I said that I got a Raspberry Pi – a very very impressive $25 (mine is the $35 version) single board computer. I’ve been spending the last few days just using it to get familiar with the OS. I use Debian on the Raspberry Pi which has differences when compared with Fedora (which I use on my desktop). One problem is that when you connect a few cables to the board, they start pulling it. This makes it hard to keep it in one place and so a case is very necessary. After checking out a few ideas online, I made one myself.
This was quite easy to make. I used two transparent acrylic boards measuring 6″x4″ (thickness: 4mm). Have a look at a picture of the base. I’ll explain after that.
You can see that I’ve fitted four legs, four spacers (stand-offs) and four smaller plastic spacers (the little white cylinders among the black ones). The purpose of those smaller spacers is to raise the Raspberry Pi a little. Figuring out where to fix these was a little tricky. I searched for regions on the board where the bottom was blank, i.e. had nothing soldered on it and adjusted the spacers to go there. To do this I had to place the Pi above these, look at the bottom side through the acrylic board and move the spacers to their exact positions. After that, I marked the positions with a permanent marker. Next I used some sandpaper to roughen those points on the acrylic board and glued the spacers using Fevi kwik.
The black bars are actually metal spacers (like the one’s I used for my robots). I encased these with plastic casings (meant for putting wires together) which I found lying around. Luckily this fit perfectly. I couldn’t find larger plastic standoffs so I had to make do with these. When drilling the holes for these spacers, make sure that you keep both boards (the top and bottom) together so that the holes align correctly. Also place the Raspberry Pi on the base so that you know where exactly you can place the spacers. The spacers should just touch it so that it doesn’t move when you want to connect/disconnect any cables. I made a mistake of not accounting for the SD card slot so you will see an extra hole below the top left spacer.
Next, I drilled four more holes for the legs of the case and the base was complete. Here is a top view of the same thing:
Finally I placed the Raspberry Pi into the case, fixed the top board on to the spacers and the case was complete.
So that’s about the case. Do let me know if you found this useful or if you have any ideas on improving this.
Before I move on to the next part, I have two things to tell about the Raspberry Pi. The first thing is that when you get your board, enable SSH. There is a nice tutorial on the Raspberry Pi wiki for this. This helps because you do not need to connect a keyboard and mouse every time. You can just connect the Raspberry Pi to your router and login through your desktop via SSH. If you want a GUI interface, install a VNC Server such as tight VNC and use a VNC session.
The next thing I want to tell you is about something interesting that came up in the comments of my previous post. Chris McClelland is the author of an application called FPGALink which can talk to various FPGA boards. What’s really interesting is that he has an ARM build for this which works on the Raspberry Pi! I found it really cool that I can now use my Raspberry Pi to program an FPGA board. Do check out his page for the software.
Now for part 2. One problem I have whenever I solder is that the spool of solder doesn’t sit in one place. It’s hard to continuously pull solder as you need it. I thought of buying a little stand but I couldn’t find one. So I decided to make one my self.
It’s not something flashy. I’m not even going to describe how I made it because I think the picture tells enough (do feel free to post questions in the comments section if you have any doubts though. I will be glad to help). If you use larger spools of solder, make a stand like this. It makes things so much more convenient!
Finally, I needed a convenient 5V source. I have a 10V battery and a couple of 10V adapters but no 5V sources. I need one for my FPGA board and I know I’ll need one when I prototype simple logic circuits on my breadboard. So I made one using a 7805 IC. The circuit is from ST Microelectronics’ 7805 datasheet’s application notes. I replaced the 0.33uF capacitor with a 10uF as that was the only higher value I had. If the 7805 which you buy is from a different manufacturer, refer to their datasheet. National Semiconductor (now part of Texas Instruments) recommends 0.22uF capacitors in their datasheet. I’ve uploaded the eagle files on box.net. Check the sidebar for 5v7805.zip for the schematics and PCB layout. Here is what it looks like when finished:
So that’s it for this post. Hope you found these useful. Do let me know what you think in the comments. In my next post, I’ll give a small demo on my Nexys3 FPGA board. I am currently working on using it’s USB-UART interface so that I can talk to the board from my computer. There is code available on the internet but I want to do this myself so that I can learn. I will obviously post a tutorial when I’m done so stay tuned. Thanks for reading!