To take advantage of the freedom wireless networking offers I wanted to integrate the BeagleBone Black Wireless and the 4.3" LCD touch screen cape into a fully portable development kit.
Rather than trying to print or build an enclosure from scratch, I shopped around to find a small plastic lunchbox of the right size and proportions. I secured the BeagleBone Black Wireless to the bottom of the Lunchbox with 25mm long M3 standard bolts – just the right size to fit the mounting points on the board and long enough to secure the LCD display cape in place. This will help with keeping it in place when additional capes are inserted as the pins have quite a tight fit.
I really wanted all the potential of the BeagleBone to be available in the Lunchbox kit. As part of this the two rows of headers need to be accessible to allow for adding of more capes or even other things like LEDs, GPIO switches or for interfacing small motors and sensors. As the board is mounted to the bottom and the lunchbox is deep enough, most capes can be attached and integrated while still allowing the lid of the Lunchbox to be attached.
Wireless is great for networking, but still being tethered to a power outlet negates that advantage. Fortunately, the BeagleBone Black Wireless can be powered over USB, so some smartphone power banks are able to provide a battery solution. Some smaller or cheaper units may not provide enough power to run the BeagleBone Black Wireless and the LCD display simultaneously, so I made sure to use a battery bank that could provide at least 1 amp of current. I took the battery and circuitry out of the plastic case of the power bank and used mounting tape to attach it to the side of the Lunchbox. I cut a slot to give access to the charging port for the battery and twisted a small micro USB cable around to the port on the BeagleBone Black Wireless. A good tip when assembling this is to have the battery completely discharged so you can test out various fitting positions for the cable without worrying about the BeagleBone Black Wireless turning on.
Fortunately the BeagleBone Black Wireless has integrated power and reset buttons, meaning the battery could be connected directly to the micro USB port without having to put a switch in line. The first time it is connected the board will power on, but after shutting it down it can be turned back on with the power button located near the wireless antenna on the board.
Connecting a range of things like a keyboard, mouse and a USB thumb drive quickly makes one USB port inadequate, so I integrated a 4 port USB hub into the build. I couldn’t use an actively powered hub as the small battery wouldn’t supply enough power to run it. This unfortunately means high power devices like a hard drive will not work, but low power peripherals like keyboards will function perfectly. I cut a hole and mounted the hub to the right side of the box and secured it in place with some thin nuts and bolts.
I didn’t want the LCD display to be irremovably fixed to the Lunchbox, so rather than a permanent adhesive I used double sided mounting tape to fix the panel to the bottom. Over time it may become a little loose, but this way it can be easily removed with a thin craft knife. I cut a thin slit on the edge of the Lunchbox to fit the LCD ribbon cable through to the BeagleBone Black Wireless underneath. I was careful that the cut slit didn’t have a very sharp edge, as this would wear away at the fragile ribbon cable. To help keep it in place I fixed it in place with a strip of electrical insulation tape.
To have some redundancy if the BeagleBone Black Wireless is used without the display cape I needed the HDMI port to be accessible. I used an adapter to convert the micro HDMI into a more common full sized HDMI port. The adapter slotted into a small hole in the side of the Lunchbox. To stop it wiggling loose I stuck it in place with a glob of hot glue.
I sprayed the completed Lunchbox with a metallic silver paint to give it a more sophisticated finish. To give it a little bit of iconography I taped an image of the BeagleBoard.org mascot inside the box and used painters tape to keep that area unpainted on the outside.
| List of Materials |
|---|
| BeagleBone Black Wireless with WiFi and Bluetooth |
| Element14 4.3 inch TFT LCD Display Cape with capacitive touch |
| 5x M3 x 25mm Nuts and Bolts |
| micro HDMI to HDMI adapter |
| 4 port Bus Powered USB Hub |
| USB Lithium battery Powerbank with 5v minimum 1000mA output |
| 8GB class 4 micro SD card |
If you have any questions or suggestions for improvement about this BeagleBone Black Wireless in a Lunchbox project, comment below and I’ll do my best to answer. I’d also be very interested to read about any other development platforms or single board computers that have been put together in a case with some peripherals to make a custom portable unit.