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Juicebox: Home
Juicebox is an embedded computer designed to form the core of a simple ebook/MP3 player device. Some of its features are:
  • Small form factor: 50x56x3.7 mm
  • Interfaces with Multimedia card
  • Can scan a small E Ink panel directly (A2, Stingray, etc.)
  • Bidirectional communications with standalone display controllers
  • 8 bit AVR running at 8MHz for the CPU
  • 128K External RAM
  • Serial terminal
  • Software developed using GNU tools
  • MP3 decoder/headphone amp
  • Lithium Ion battery charger
  • Supports 4x12 cell phone LCD
  • 32.768kHz low speed xtal for RTC function
  • Temp sensor
  • Pads for external hall sensor
  • Pads for 4 membrane switches on PCB

A block diagram of the system:

Current Revision is: x02
Hardware design/low level drivers: Holly Gates
Software: Brian Hone, Becky Moran

Project dowload files are now hosted at:

Potential Devices
Portable viewer/ebook
One potential use for Juicebox is in conjunction with an E Ink display. The board is designed to mount to the rear of an E Ink TFT module and interface via the 30 way FPC connector. There is also an interface connector spaced further towards the center of the juicebox board, in case the device design calls for the controller board to overhang the edge of the TFT (for instance, in order to have buttons on the front face of the device, as supported for rev x02). The thickest part of the board is over the MMC slot, which is 3.7mm. This is also the height of the li-polymer battery, so including the E Ink module, the entire component stack up including an adhesive layer is less than 5mm. If a case is built using say 0.5mm titanium sheet on either side, a device thickness of 6mm could be acheived. This is about half as thick as a palm V.

E Ink is a good disply choice for this controller since juicebox can only scan the display relatively slowly, and probably can't do any other tasks while scanning the display. Fortuntately, the E Ink panel only needs scanning when you want to change the image. This also means that most of the time the controller and panel can be in sleep mode and power consumption can be kept at a minimum.

Originally, I thought there might be enough processor bandwidth to enable keeping the MP3 decoder busy while also updating the display. Sadly this is not the case, as either activity almost maxes out the processor. Would be nice to have something faster in there...

For the Society for Information Display 2003 in Baltimore, I made the ebook/MP3 player shown below. It should operate for about 10 hours of display update or MP3 play from the 2 lithium polymer batteries in there.

I made the case entirely out of laser cut acrylic, backprinted on the front piece with screen printing ink (thanks to JD Albert for helping out with that!). The front piece is stuck to the core with 3M 300LSE adhesive, and the back is held on with 2-56 torx stainless screw driven into laser cut and hand tapped holes in the core. The full package is 7.5mm thick, since I used acrylic for the front and back sheets. If titanium was used it could be thinner, but I sort of like the way the acrylic looks.

Buttons are membrane switches mounted to the back of the juicebox PCB, with hand sanded lozenge buttons mounted on top.

Here is a back view:

And some action shots:

For the show we had it set up with 2 playlists (one for images and one for MP3s), which were synched up. So hitting the bottom of the two big buttons would advance to the next image/MP3, and hitting the other one would go back.We had a few news releases and dictionary pages, with a narrator reading them on MP3. Then we had a few that were more like single frame music videos; just an image to go along with a song, like a picture of snoop to help you get in the mood for one of his tracks.

Standalone MP3 player
Another option would be to use an small LCD instead of the E Ink panel, and to package the components differently. This would give you a pocket size MP3 player, a bit smaller than a business card in footprint, and about 9mm thick.

Here are two pictures of what the innards of such a system might look like, using an Epson LCD from a cell phone:

As part of my development for the ebook above, I also did an MP3 only case, lasercut out of acrylic and constructed in a similar way to the ebook case. I have a new case designed with some graphics on it, but I screwed up the scale somewhere along the way so when I cut, it was the wrong size. I'll fix that pretty soon. Anyway, the device is 11.5mm thick with the acrylic covers. I also had room to mount a 3.5mm stereo jack, which is way nicer since I have not been able to find a set of headphones which can do 2.5mm without an adapter. So far we have track selection, volume control, playing/pausing/stopping, and song display working for this.

My friend Ara and his little brothe want to hook up a GPS board to the serial terminal and make a GPS device, maybe with maps or coordinates or something, as well as some audio messages via canned MP3s. Brian and I have some other ideas too...

Design partially original and partially ripped off from other websites
by Holly Gates