Friday, July 26, 2013

Raspberry Pi Portable Case Build

(my Raspberry Pi)

I have been working on a case for a Raspberry Pi. The Raspberry Pi is a small single board computer that runs Linux. You can check out a few videos describing the board and the Raspberry Pi Foundation's goals. My plan was to make a pocket sized clam-shell palmtop computer similar in size and inspired by the HP-200 LX palmtop computer from 1994.

(picture from Wikipedia with iPhone for size comparison)



The plan is to have both a screen and keyboard. It is currently powered by 2 18650 batteries in series. Here it is running off the batteries with a screen. The screen is relatively cheap and was sold as a screen you would have in your car showing a camera for use as a backing up camera system. As such it is designed to be powered from a cars 12 volt battery. I have mine running straight from the 18650 batteries. See Cheap Miniture LCD Screen. Also on this page is a link to converting the screen to run from 5 volts. It seems as if the screen internally runs at 5 volts but has a regulator to drop down the 12 volts coming in from the car battery. A cheap circuit board with a switching regulator chip bought from ebay regulates voltage from the batteries down to 5 volts to power the Raspberry Pi. In the picture I have the power hooked straight into the GPIO see the pin-out here. However, I think in the future I will power the pi via a powered USB hub (which can be seen just above the Raspberry Pi board in the photo below) instead of directly into the GPIO.

The screen is not of great quality. A possible alternative is using a 4.3 inch LCD via HDMI that is used in the HTC Desire HD.

Another note on power consumption: At some point I may try and swap out one of the chips on the Rasp Pi board for better battery life. A 3.3 volt regulator can be desoldered and swapped out for something more energy efficient. Check out some info on that here and here.

I decided to make the case of 2mm think aluminium. Below is a knock up held together with tape to see if everything fits.


 To the left is the battery holders for the rechargeable 18650 batteries. On the Pi board I have at this point removed the USB port to make more room as this port will be connected directly to the USB hub. On the back panel from left to right is a hole external power input, audio jack and 4 USB ports. Below is the back panel showing the USB ports.


It is held together with a 2 part epoxy called JB-Weld. 


  

The keyboard I intend to use is an XBox 360 chatpad. Info on getting it communicating with the Pi can be found here

Slowly I am learning how to work the aluminium into the shapes I want and it has required quite a few tools. Information and a few tips I wish I knew when I started I will post in an upcoming blog post.

Unfortunately it is larger than I had anticipated and you would need to have a rather large pocket to fit it into. I like the palmtop form-factor and it seems to be something that is not at all popular in part I think due to smart-phones.

Still to make is the top half of the case holding the LCD screen and the panel that will hold the keyboard. Also all the wiring is yet to be done. I have begun to research a way to finish off the exterior of the case, perhaps with either polishing or painting.

Another some what similar project by Ben-Heck.

And, a picture of my electronics work bench: