PXD20RM Datasheet, PDF (536/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

The address of the first value in the CLUT is defined in the LUOFFS bit field of register 4 and the CLUT
is the RAM block dedicated to the DCULite which is described in Section 12.4.6, CLUT RAM. Since the
ARGB values stored in the CLUT are 32-bit ARGB, there is no need for further adjustment before
blending.
The DCULite also supports graphics encoded using luminance and chrominance format. This format is
generically known as YUV and stores the luminance (brightness, Y) of a pixel separate from its
chrominance (color information, U and V). This format is widely used by cameras and is supported by the
PDI for direct video in as well as the DCULite when stored in memory for display on a layer. The specific
implementation used by the DCULite is more accurately described as YCbCr422 which uses twice as
many bits to describe the luminance as to describe the blue (Cb) and red (Cr) difference of the
chrominance.
The DCULite takes these pixels and converts them to RGB format using equations configured using its
LYR_LUMA_COMP, LYR_CHROMA_RED, LYR_CHROMA_GREEN, and LYR_CHROMA_BLUE
registers. The YCbCr format specifies a common chroma setting for two pixels; however, it is possible to
interpolate the chroma for the pixels rather than setting both to the same value. Due to the additional
conversion step required, the DCULite is able to blend a maximum of one layer encoded in YCbCr for
each pixel. This feature is enabled by the LYR_INTPOL_EN[EN] field (see Section 12.8.1.6.3, YCbCr
mode).
There are four additional formats defined by the BPP bit field. These configure the graphic in transparency
mode and luminance mode (see Section 12.4.4.6, Transparency mode and blending, and Section 12.4.4.7,
Luminance mode, respectively).
There is a set storage format for each data format provided by the DCULite. These formats can be seen in
Table 12-58 to Table 12-67.
Table 12-58. Data layout for BGRA8888
Address
offset
0x00
0x08
[0:7]
B0
B2
[8:15]
G0
G2
[16:23]
R0
R2
[24:31]
A0
A2
[0:7]
B1
B3
[8:15]
G1
G3
[16:23]
R1
R3
[24:31]
A1
A3
Table 12-59. Data layout for YCbCr422 format¹
Address
offset
[0:7]
[8:15]
[16:23]
[24:31]
[0:7]
[8:15]
[16:23]
[24:31]
0x00
Cb0
Y0
Cr0
Y1
Cb2
Y2
Cr2
Y3
0x08
Cb4
Y4
Cr4
Y5
Cb6
Y6
Cr6
Y7
1 _{The YCbCr422 format encodes chroma information across two pixels. Therefore, the chroma values apply to the even pixel}
denoted in the table and its adjacent odd pixel.
12-74
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor