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Functional Description (Continued)

3.2.8

CRC Signature

The CS9211 contains hardware logic that performs Cycli-

cal Redundancy Checks (CRCs) on the panel data digital

pipeline, using the polynomial 1 + x3 +x4 +x24.This feature

is used for error detection during silicon and design valida-

tion and makes it possible to capture a unique 24-bit signa-

ture for any given mode setup. An error in the dither/FRM

pixel pipeline will produce a different signature when com-

pared to a known good signature value. Various logic

blocks can be configured, as shown in Table 3-14. This

allows the programmer to quickly and accurately test data

processing without having to look for incorrect pixels on the

screen. In the FRM block test, each frame will produce a

different signature in a sequence, which repeats after 64

frames. The signature and the corresponding frame count

can be read from the register Offset 42Ch. Table 3-15

shows the bit formats for the register that controls this fea-

ture, and Figure 3-12 shows a simple block diagram.

Figure 3-12. CRC Data Path

CRC

Signature

PANEL_DATA[23:0]

(LD/UD)

Offset 2Ch[31:8]

Address

SHFCLK

Frame Count

Offset 2Ch[7:2]

VSYNC/FLM

FRAME_CNTR

Table 3-14. Logic Functions Affecting the CRC

Dither Enable for

TFT/DSTN/SSTN

Bypass Dither for

TFT/DSTN/SSTN

FRM Enable for

DSTN/SSTN

FRM Bypass for

DSTN/SSTN

Bypass CS9211

Offset 40Ch[6:0]

000,001,1

001,010,1

010,011,1

011,100,1

100,101,1

101,XXX,X

Offset 40Ch[6:0]

101,XXX,X

Changes with the Frame

Count (0 to 31)

Note: Generates the sig-

nature (Offset

42Ch[31:8]) for a given

frame count (Offset

42Ch[7:2])

LFSR = 00

FRM_RAM Contents =

all 0’s

Offset 404h[30] = 1

Table 3-15. Panel CRC Signature Register

Bit

Name

Description

Offset 42Ch-42Fh

Panel CRC Signature Register (R/W)

Reset Value = xxxxxxxxh

31:8

SIG_DATA

Signature Address (Read Only): 24-bit signature data for dither logic or FRM logic.

7:2

FRAME_CNT

Frame Count: Represents the frame count, which is an index for the generated signature for that

frame.

1SGFR

Signature Free Run: The value of this bit during the first cycle of a frame determines whether a signa-

ture will be generated for that frame. If this bit is kept high, with signature enabled (bit 0 = 1), the signa-

ture generator captures data continuously across multiple frames. Changing this bit from high-to-low

causes the signature generation process to stop after the current frame.

0 = Do not capture signature during next frame.

1 = Capture signature during next frame.

0SIG_EN

Signature Enable: Enables/disables signature capture. 0 = Disable; 1 = Enable.

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