LM9830 datasheet(37/45 Pages) NSC

37 / 45 page

http://www.national.com

from the LM9830 in a continuous stream. First, write to register 3

to set what the data is (gamma or offset/gain) and what color

(red, green, or blue) the data is for. Then write to registers 4 and 5

to set the initial address (usually 0), and the R/W mode (R in this

case). To read data from the DataPort, the DataPort address (6)

needs to be inserted before every read to prefetch the data from

the external SRAM. The timing is shown in Figure 59. Note that

this applies

only to offset and gain coefficient reads; the gamma

table may be read with or without the additional address writes.

The DataPort Address stored in registers 4 and 5 will be automat-

ically incremented after every read (if reading gamma data) or

every second read (if reading offset/gain coefficient words).

8.0 Scanning

8.1 Start Scanning - Initiating an Image Scan

An image scan is started by setting the Scanning bit in the Con-

figuration Register. The LM9830 will move the paper forward the

number of steps specified in the Stepper Motor Configuration reg-

ister and begin scanning. Scanning ends when the host writes a

new command to the command register (Idle, Paper Feed to Start

or Paper Feed to End) or when Paper Sensor #1 or Paper Sensor

#2 changes state (if programmed to do so).

The line buffer is reset when the Scanning bit is SET, not when it

is cleared. The host can continue to read stored data out of the

line buffer after a scan has stopped.

The LM9830 pixel data is read from configuration register

address 00. To read pixel data, the host should latch address 00

into the LM9830’s address pointer. Subsequent reads from the

host will read the next byte of pixel data stored in the line buffer.

Here are examples of two consecutive image data reads in the

three possible interface modes:

Image data can flow as fast as possible from the LM9830 to the

host, but can be interrupted at any time (by latching a different

address) to read the LM9830’s status registers, abort the scan,

etc.

If for some reason you want to pause the scan for some length of

time and resume later, do NOT reset the Scanning bits (return to

Idle). Simply stop reading pixel data. When the buffer fills up, the

LM9830 will automatically stop scanning and turn off power to the

stepper motor (when the delay goes beyond the time specified in

the Hold Current Timeout register).

The last byte of every line is the status byte (register 02). If the

line just transmitted was the beginning of a stepper motor pause

or reverse cycle, the Pause bit is set. For scanners unable to

reverse, this feature potentially allows the software to correct

images distorted by motor starting/stopping.

8.2 Reconstructing the Image Data Received By the PC

When reconstructing an image from the stream of data received

from the LM9830, it is useful to know the format of the data. The

LM9830 does not perform deinterleaving on the pixel data, it

comes out exactly as the sensor sends it. Deinterleaving and

other processing must be performed on the host PC.

For a single output CCD/CIS that outputs one line of data with

colors alternating at the line rate, the output format is:

R1, R2, R3, R4,..., Rn-2, Rn-1, Rn (line m)

G1, G2, G3, G4,..., Gn-2, Gn-1, Gn (line m + 1)

B1, B2, B3, B4,..., Bn-2, Bn-1, Bn (line m + 2)

For a triple output CCD/CIS that outputs 3 lines of data (each x

pixels apart in the vertical direction) with colors alternating at the

Datan

CS (INIT)

D0 - D7

Figure 59: Reading Gain and Offset Coefficients

through the DataPort (µP mode)

(STROBE)

ALE

(SELECTIN)

(AUTOFEED)

Datan+1

Pixel n+1

STROBE

AUTOFEED

BUSY

Pixel n

D0 - D7

Figure 60: Reading Pixel Data (EPP)

SELECT IN

STROBE

AUTOFEED

BUSY

D0 - D7

Figure 61: Reading Pixel Data (Nibble Mode)

SELECT IN

ERROR (D0, D4)

SELECT (D1, D5)

PE (D2, D6)

ACK (D3, D7)

D7-D4

D3-D0

D7-D4

D3-D0

NIBBLE

CS (INIT)

RD (AUTO-

FEED)

Pixel n

D0 - D7

Figure 62: Reading Pixel Data (µP)

Pixel n+1

(STROBE)

ALE

(SELECTIN)

LM9830 датащи(PDF) 37 Page - National Semiconductor (TI)

LM9830 датащи(HTML) 37 Page - National Semiconductor (TI)

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 38 39 40 41 42 43 44 45

датащи скачать

ссылки URL