AN2641 datasheet(14/37 Pages) STMICROELECTRONICS

14 / 37 page

CLCD controller dataflow

AN2641

14/37

Doc ID 14027 Rev 1

activity of the addressed pixels over a programmed number of frames to provide the

effective display appearance.

●

For TFT displays, either an addressed palette value or true color value is passed

directly to the output display drivers, always bypassing the grey scale algorithm logic.

Three major components of the data flow are:

Pixel Serializer, this block reads the 32-bit wide LCD data from output port of the DMA

FIFO and extracts 24, 16, 8, 4, 2 or 1 BPP data, depending on the current mode of

operation. The CLCD controller supports big endian, little endian and WinCE data

formats.

Dependent upon the operation mode, the extracted data may be used to point to a

color/gray scale value in the palette RAM or may actually be a true color value that can

be directly applied to an LCD panel.

Palette RAM is a 256 x 16 bit dual port RAM (physically structured as 128 x 32 bits)

with independent controls and addresses for each port. Port1 is used as a read/write

port and is connected to the AMBA AHB slave interface. The palette entries can be

written and verified through this port. Port2 is used as a read-only port and is

connected to the gray scalar.

Table 2 shows the bit representation of each word in the palette.

A gray scale algorithm drives mono and color STN panels. This provides 15 gray

scales for mono displays. In the case of STN color displays, the three color components

(RGB) are gray scaled simultaneously which results in 3375 (15 x 15 x 15) available

colors. The gray scalar transforms each 4-bit gray value into a sequence of activity-per-

pixel over several frames to give the representation of gray scales and colors.

Table 2.

Palette data storage

Bit

Name

Description

[31]

Intensity/unused

[30:26]

B [4:0]

Blue palette data

[25:21]

G [4:0]

Green palette data

[20:16]

R [4:0]

Red palette data

[15]

Intensity/unused

[14:10]

B [4:0]

Blue palette data

[9:5]

G [4:0]

Green palette data

[4:0]

R [4:0]

Red palette data

AN2641 データシート(PDF) 14 Page - STMicroelectronics

AN2641 データシート(HTML) 14 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

データシートダウンロード