Rastergraf
3-12 Programming On-board Devices
Display Memory Size
The pixel size is programmable to 8, 15, 16, or 32 bpp. The SGRAM on
the Borealis is either 16 MB or 32 MB, where a MB = 1024 * 1024 bytes.
Calculate the possible display formats based on these values.
Note that you can render into SGRAM that is not being used in the active
display, and by changing the starting address register in the Borealis pan
to it so it is visible or BitBLT the Pixmap data to a static display window.
3.5 Eclipse3 Optional Features Register
Although most functions on the Eclipse3 are self-contained, it is necessary
to maintain a few extra control bits for supplementary features. Using the
Micrel MIC74 I
2
C 8-bit I/O register, the graphics board supports an
auxiliary register.
All bits come up tristate and have pullups except I2CMUX which has a
pull down.
Table 3-2 Eclipse3 ACR Register Bit Assignments
Bit Mnemonic
Value
Function
Description
0 REDLED
0
1
on
off
Red LED
1 AMBLED
0
1
on
off
Amber LED
2 GRNLED
0
1
on
off
Green LED
3 I2CMUX
1
0
local
monitor
Switches the Borealis DDC2B/I2C
control lines between local devices
(THC63DV164, Serial EEPROM, and
LM75) and the display monitor.
5, 4
--
-
not used
--
6 PBSEL
0
1
high bank
low bank
Selects between the high and low 64
KB of Flash PROM when JP101 is
not
installed.
JP101( installed) overrides this bit
(forces low).
7 --
-
not
used
