HOME PROJECTS PEOPLE BREWING LETTERPRESS ...
H2 image

H2
Home | Up
Operation
Hardware
Software
Communications
Cases

   
H2 - Hardware
Overview
The main system components of the H2 are:

  • Gumstix SBC - from http://www.gumstix.com
  • Metronome 834 or Apollo display controller board
  • Support board
  • Button board
  • Case

The Guts


Installed in a case

Gumstix SBC
The Gumstix board is available directly from Gumstix, Inc. This is the Gumstix-f version, assembled with a low profile Molex stacking connector instead of the standard Hirose stacking connector. When installed in a case, the MMC connector is demounted and attached remotely either through a flex adapter or by discrete wires to the support board.
Display Controller
Two display controller options are available.

Apollo
This is the design used in the Librie, and was developed primarily by Philips. It uses the Apollo display controller ASIC.

Metronome 834
This is the design shown in most of these pictures. A Xilinx CPLD is the heart of the controller, and interfaces to the gumstix over the LCD peripheral port included with the X scale processor. Updates are performed from the host by changing the frame buffer data accessed through /dev/fb0 and scanned out continuously over the LCD port.

Support Board
The support board connects the gumstix board to the display controller, the serial terminal, and power. It also has a power management IC to provide 3.3V, 4V for the gumstix, and to charge Li-ion batteries.
Button Board
The button board comes in two versions, long and short. The long board works well in the alkaline case design, and the short works better in the Li case design. The button board connects to the support board via a 10 pin 0.5mm FFC or discrete wires if the connectors are not mounted.
Power
Power comes from one of three places:

12VDC wall power
This is used to operate continuously or to charge batteries.

Li-polymer batteries
We use two thin Li-poly cells. Originally we used some cells from Kokam, obtained through the RC plane industry, and connected in parallel. Now we have moved to some Varta cells connected in series.

Alkaline AAAs
AAAs have fairly high internal resistance and don't like being hit with spikes (like when the radio is working or when you are doing a display update). To smooth this out, we tried a thin film supercap in parallel with the batteries, which definitely helped extend their life.

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