LM9830 datasheet(14/45 Pages) NSC

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COMMAND REGISTER

Command Register

This register is used to start and end a scan.

It is also used to home the sensor in a

flatbed scanner or eject the image in a

sheetfed scanner.

Idle - Stops motor (A, B, A, B = 0),

completes current line of data (if scanning).

Note: CCD/CIS clocks continue clocking.

High Speed Forward - Moves motor forward at a

speed determined by the Fast Feed Step Size

(registers 48 and 49).

High Speed Reverse - Moves motor backward at a

speed determined by the Fast Feed Step Size

(registers 48 and 49).

Start Scan - Resets the LM9830’s data pointers and

starts an image scan.

Standby

When this bit is set the crystal oscillator

continues to run but all internal clock signals

are frozen. The analog circuitry is turned off

to reduce power consumption.

Operating

Low Power Standby Mode

Reset (Host must write a 1 then a 0 to enter

and exit the reset state)

Normal Operation

Resets the LM9830

MASTER CLOCK DIVIDER

MCLK Divider

This register sets the master clock frequency

for the entire scanner.

fMCLK = fCRYSTAL/MCLK_Divider

fADC = fMCLK/8

0 00000÷1.0

0 00001÷1.5

0 00110÷4

a aaaaa÷ ((aaaaaa/2)+1)

1 11110÷32.0

1 11111÷32.5

HORIZONTAL RESOLUTION AND DATAMODE SETTINGS

Horizontal DPI Divider

This register determines the horizontal

resolution of the scan.

Scan resolution = Optical resolution divided

by the Horizontal_DPI_Divider.

000÷1

001÷1.5

010÷2

011÷3

100÷4

101÷6

110÷8

111÷12

Pixel Packing

This register determines how many bits in

each byte of data are transmitted to the host

when DataMode = 0

0 0

1 bit/pixel (1 bit grayscale/3 bit color)

0 1

2 bits/pixel (2 bit grayscale/6 bit color)

1 0

4 bits/pixel (4 bit grayscale/12 bit color)

1 1

8 bits/pixel (8 bit grayscale/24 bit color)

DataMode

When DataMode = 0, the pixel data is fully

processed, going through the Offset,

Shading, Horizontal DPI Adjust, Gamma,

and Pixel Packing blocks.

When DataMode = 1, 10 bit data is extracted

following the Horizontal DPI Adjust stage.

Gamma and any other post processing must

be done by the host.

When DataMode = 1, Horizontal DPI Adjust

= 0, and the Offset and Gain coefficients are

set to 0, the 12 bit data straight from the

ADC is transmitted. Offset, Shading,

Gamma and any other post processing must

be done by the host.

1, 2, 4, or 8 bit image data,

as determined by the Pixel Size setting.

10 bit image data - sent in 2 bytes:

X X X X 9 8 7 6- 5 4 3 2 1 0 X X

12 bit image data - sent in 2 bytes:

X X X X 11 10 9 8 - 7 6 5 4 3 2 1 0,

Horizontal DPI Divider = 0.

Address

Function

Value

LM9830 Datasheet(PDF) 14 Page - National Semiconductor (TI)

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