Datasheet

AN1368
DS01368A-page 18  2011 Microchip Technology Inc.
The GPUs are briefly explained below:
• CHRGPU: Renders the characters on the display.
A font table must be loaded into the RAM and the
CHRGPU must point to that font table. The (x, y)
coordinates must also be initialized on the appro-
priate CHRGPU registers. When a character code
and the draw command are given, the character
will be rendered on the configured RAM area,
which can also be the frame buffer. The user must
take care of the display glass orientation as the
characters cannot be rotated dynamically by the
CHRGPU. The CHRGPU does not support anti-
aliased fonts; all the pixels on a character are of the
same color. The background and foreground colors
are set using the CHRGPU commands. If transpar-
ency is enabled, only the foreground color is
drawn, and if the transparency is disabled, the
background color is also drawn surrounding the
character. To use the CHRGPU by default, uncom-
ment the line: #define USE_DRV_OUTCHAR in
MicrochipGraphicsModule.h.
• RCCGPU: Used to draw horizontal or vertical
lines, rectangles, filled rectangles, and to copy
rectangular regions. RCCGPU can perform the
following three operations:
- Copy – Copy a memory block from one part
of the RAM to another. Depending on the
command parameter, the block of memory
can be a contiguous block or a rectangular
block.
- Copy with Solid Fill – Fill a rectangular area
with a specific color.
- Copy with Transparency – Same as the copy
option, but a color set apart to indicate trans-
parency will not be copied to the destination,
leaving that part of the destination
unchanged.
Each operation can use one of the 16 available logical
operations, called Raster Operations (ROPs), which is
applied while copying.
For example, source can be copied as is or the source
can be ORed with the destination area, or the source
can be ANDed with a separate region and copied to the
destination area. For more information on the Graphics
Controller Module (GFX) and the supported ROPs,
refer to the Section 43. “Graphics Controller Module
(GFX)” (DS39731) in the “PIC24F Family Reference
Manual”.
The RCCGPU can be used to achieve special effects,
such as screen animations, like scrolling, peeling, etc.
For more information on the advanced usage of the
RCCGPU, see Appendix C: “Advanced Usage of
RCCGPU”.
• IPU: Used to decompress a compressed data
using the DEFLATE algorithm with Fixed Huffman
codes. For example, images can be compressed
and kept in the internal Flash or external memory
and they can be decompressed into RAM during
run time. Similarly, compressed user-specific data
can also be decompressed and used during run
time with the IPU. It should be noted that
decompression can only commence from the
beginning of a compressed block and not from the
middle. For example, when storing multiple
images, compress each image to its own
compressed block. The IPU can be used to
decompress any images by specifying the
location of the desired compressed block. The
Microchip Graphics Library will handle this
scenario, making it transparent to the users.
For more information on these GPUs and their
registers, refer to Section 43. “Graphics Controller
Module (GFX)” (DS39731) in the “PIC24F Family
Reference Manual”.
Note: Bit maps can be compressed by selecting
the “IPU” option in the Graphics Resource
Converter (GRC) tool while converting the
images. GRC is a tool included in the
installation of the Graphics Library. The
PutImage() API automatically decom-
presses these compressed images using
the IPU at run time. The user is required to
allocate the required amount of RAM for
IPU operation, using compile-time options
as described in the Microchip Graphics
Library Help file.