CYGPKG_DEVS_FRAMEBUF_ARM_CSB337900 -- eCos framebuffer support for a CSB337/900
This package provides an eCos framebuffer device driver for a Cogent
CSB337 board with a CSB900 add-on to provide the LCD panel. It has
dependencies on both pieces of hardware so cannot be used with any
other combination. The driver is a hardware package and is loaded
automatically when configuring eCos for a csb337900 target, but not
when configuring for a vanilla csb337 target. By default it is
inactive and does not add any code size or data overheads. To activate
the driver the generic framebuffer package
CYGPKG_IO_FRAMEBUF should be added to the
configuration. The driver's functionality is only accessible via the
API defined by the generic package.
There are a number of design issues with this hardware combination.
The framebuffer memory cannot be accessed in the conventional linear
way, Instead the driver contains custom drawing code which will be
significantly slower than the equivalent linear framebuffer routines.
There are also problems with the colour handling: only three bits of
control are available for each of red, green and blue intensity,
The driver supports four cyg_fb structures:
cyg_csb337900_fb_320x240x8r270. These all run the
hardware in the same resolution but in the four different
orientations, using hardware to perform the rotation. The
corresponding identifiers for the macro API are
240x320x8r180 and 320x240x8r270.
Obviously only one of these framebuffer devices can be used at a time.
All the devices implement 8bpp non-linear displays with a writeable
palette. The supported ioctl operations are
CYG_FB_IOCTL_BACKLIGHT_SET. The backlight can only
be switched on or off, there is no support for different levels of