| |
|
|
|
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
|
|
|
|
|
|
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.
|
|
|
|
|
|
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.
|
|
|
|
|
|
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.
|
|
|
|
|
|
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 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
|