RASPI – Part 1 – Baking the Pi

 

In all honesty while this enclosure looks great and is well machined/lasered  it was an absolute pain in the butt to assemble.  One piece, a standoff (picture later), was different then shown in the assembly instructions in that it had a “tab” which looked as if it was to engage a hole in the board.  No matter how I tried it would not engage this hole and caused the board to be offset so that external cables would not connect, so I snipped it off.  Anyway it is complete and “online”.  Here is what you need

Here is what you need to “bake” a pi starting at top right to bottom:1.  a power supply – a USB plug
2.  a 26 pin flat ribbon cable with connectors
3.  a raspberry pi
4.  a usb wireless nic – use an ASUS N10.  It is on the approved list of hardware for the pi.
5.  a SD card – I am using a Lexar 32gig class 10.  The higher the class the faster the card.
6.  the quarter is not required
7.  Some type of enclosure – a pie shell if you will.  I won’t give this items name out because I would not use this one again.  In fact I have ordered a transparant case to replace this one.
8.  an Exacto knife.  You will need it to remove the brown paper from both sides of the enclosure panels  and from the led pipes.  This is time consuming, especially around the laser etched lettering where it does not come off with the “peel”.
IMG_0460Below:  a closer lookIMG_0462

Below:  the pi

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I am not showing all of the steps for assembly as he has done that on his website.  I will however show some pics that might speed the process where it is not clear.  The are 5 clear led pipes.  Yours will be blue until you remove the plastic film covering them.  If you don’ remove the film they won’t fit.  The tolerances are very tight and that in my estimation is part of the difficulty when assembling.  These pipes go into the holes in the top picture and extend down to rest on top of the pi board leds  when it is inserted.  Also note that in the top pic the 5 pipes will have to mesh with 5 cutouts in the a side piece installed later. IMG_0463IMG_0464
This piece has a small “ear” sticking up on the right side.  At first I thought it was a new design such that it would engage a hole on the Pi board, but when I inserted this bottom piece it either did not engage the hole or would not seat properly causing the board to rise up so that the power connection did not align with its cutout.  I nipped it off this “ear”  and inserted the bottom piece it as per instructions.  Tightened the 4 posts. IMG_0465
Done.  I thought I had taken a picture of the flat ribbon cable where it attached to the board but did not.
In the top picture the right side of the ribbon cable is white (double click for a larger image).  That white pin must attach to pin 1 on the GPIO interface.  If for example you attach the exposed end of the cable shown in the picture to the board then this white marking would be on the left and on the wrong pin.  This would be a major problem later when attaching to a breadboard.  Once this box is together you don’t want to take it apart.  The other pictures are show n’ tell.The new case arrived so I re-baked the Pi.  It now has a transparent enclosure.  I also added some rubber feet to lift it of the surface and to prevent it from skating about.
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Note the 4 rubber feet in the picture below.  Make sure you put them on the bottom and not the top.
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All put back together again. Only the powered USB hub plugs into the Pi.  The network USB nic, diskdrive, keyboard/mounse combo, USB webcam all plug into the powered hub.

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Online and running.  This picture is the desktop of the pi on the desktop of an Ubuntu laptop.  I am using “tightnvcserver” on the pi and a vnc client on other machines.  More about this is the OS installation here . IMG_0473
I decided to run BOINC on the pi to crunch data for Asteroids@Home.
To make this “useful” I had to over clock the Pi to a medium setting.  Run time temps in my house were around 52C.  Thought this might be a bit too high so I added a USB driven fan.  No heat sinks are used on the 3 Pi components and the top lid on the case was left in place.  The resulting air flow dropped the temp to 42C.  Quite an improvement.  I am now waiting for a new Pi case with built in fan and 3 heat sinks.  Then I can overclock at its highest setting.TAKEAWAY:  look at all the cases available and buy only one.  There is also a “wet” Pi case for cooling if interested.I had considered building a Lego enclosure in the form of a wind tunnel using an 81MM USB fan but this other case is just easier.  I’ll donate the Legos.  What you see here is just to get an idea of sizing etc.  The final build was going to be in black.  They don’t seem to have the assortment of “bricks” in “clear”.
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Well the over clock kit arrived – a new case with built in fan and three heat sinks.
I installed the aluminum heat sinks be removing the paper on the thermal tape and pressing them on to the three elements that create the most heat.  You can see them installed in the first picture to the right.  A note of caution:  the top heat sink on the edge of the board must be placed such that it does not extend over the edge of the board.  If it does you will not be able to fit your case.  The fan on the top lit will almost rest on top of the heat sink in the center of the board.
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This is the hinged lid with fan attached.  The fan may be attached to the 5 volt and ground pin on the GPIO OR to the 3 volt and ground pin.  For max over clocking connect to the 5 volt.  It will run faster and generate more noise.  A problem with this kit.  If you look at the cut out on the right in this picture you might think it will accommodate the GPIO 26pin flat ribbon cable.  It will not.  The cut out is not large enough to accommodate the connector.  Also because this lid is hinged even if you could install a ribbon cable, opening this lid would be difficult.  So many types of enclosures and not all of them work as expected.  My guess is that because you are pulling power off of the GPIO that you could not use a ribbon cable anyway so it really does not matter.  Just something to be aware of.  IMG_0499
The assembled Pi in its new home.  It is powered and the fan is turning even though this picture would seem to contradict that statement.  Not noisy.

I modified the Pi to run at its “Turbo” setting.  At the previous “medium” setting it ran at around 41C with an external fan for cooling.  Now at the turbo setting it is running at around 35C without the fan used previously.

There are many options for heat sinks.  There is a copper set of sinks that while are a great option they would not work with this case because the height of the sinks would protrude into the fan, i.e., without a fan attached the central sink would touch the lid when it closed.  Be careful when trying to mix and match this stuff.  Better to buy the entire kit from one source that way you know it will mesh.

I wrote a Perl script to run every 5 minutes as a cron job that would acquire the Pi’s temp and email me if it exceeded an arbitrary value of 50C.  The only way that could happen is if the fan fails.

I am now crunching for Einstein@home.

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