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LM9831 Register Listing

Registers in bold boxes are reset to that value on power-up. All register addresses are in hexadecimal. All other numbers are

decimal unless otherwise noted.

Address

Function

D

7

D

6

D

5

D

4

D

3

D

2

D

1

D

0

Value

IMAGE BUFFER (READ ONLY)

00

Pixel (Image) Data

n n n n n n n n One byte of image data.

STATUS REGISTERS (READ ONLY)

01

Image Data Available In Buffer

nn nn nnn n

n*2 (256k x 16 DRAM) or n*8 (1M x 16 DRAM)

kilobytes of image data is available

02

PAPER SENSE 1 State

read clears bit if edge sensitive input.

0False

1True

PAPER SENSE 2 State

read clears bit if edge sensitive input.

0False

1True

MISC I/O 1 State

read clears bit if edge sensitive input.

0False

1True

MISC I/O 2 State

read clears bit if edge sensitive input.

0False

1True

MISC I/O 3 State

read clears bit if edge sensitive input.

0False

1True

MISC I/O 4 State

read clears bit if edge sensitive input.

0False

1True

MISC I/O 5 State

read clears bit if edge sensitive input.

0False

1True

MISC I/O 6 State

read clears bit if edge sensitive input.

0False

1True

DATAPORT REGISTERS

03

DataPort Target

0 0 Offset Coefficient Data

0 1 Gain Coefficient Data

1 0 Gamma Lookup Table

11 N/A

DataPort Target Color

00

Red

0 1

Green

10

Blue

11

N/A

Pause (Read Only)

This bit indicates whether or not the scanner

is currently paused due to a buffer full

condition.

0

Normal State

1

The scanner is currently in the pause/reverse cycle.

DRAM Test

0

Normal Operation

1

DRAM Test mode

04

DataPort Address - MSB

R

/

W

aa aaa a

Address of location to be read/written to.

a = 0 to 4095 for gamma tables,

0 to 16383 for Offset and Gain Coefficient Data

Addresses greater than these are illegal.

Bit D6 of register 4 indicates whether next operation

will be a Read (D6=1) or a Write (D6=0).

05

DataPort Address - LSB

aa aa aaa a

06

DataPort

nn nn nnn n

Data to be read from or written to the address of the

currently selected Dataport Target. The DataPort

Address is automatically incremented whenever one

(gamma data) or two (Gain/Offset Data) bytes are

read from or written to this register.