VSP3200 Datasheet, PDF(13/16 Page) Burr-Brown (TI) – CCD SIGNAL PROCESSOR FOR SCANNER APPLICATIONS

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VSP3200 Datasheet, PDF (13/16 Pages) Burr-Brown (TI) – CCD SIGNAL PROCESSOR FOR SCANNER APPLICATIONS

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other system circuits, as it would affect the reference

voltage of the A/D converter and prevent proper A/D

conversion.

â¢ External Reference: to set the external reference mode,

D2 of the configuration register must be set to â1â. In

external reference mode, VREF operates as an analog

voltage input pin. Inputting half the voltage necessary for

the full-scale voltage range (e.g.: 1.7V applied for a

necessary 3.4Vp-p input range), with a reference voltage

range from 0.25V to 1.75V, will create the full-scale

range. Thus, when VREF is 0.5V, the full-scale range will

be 0.5Vp-p, and when VREF is 1.75V, the full-scale range

will be 3.5Vp-p.

PROGRAMMING THE VSP3200 AND VSP3210

The VSP3200 and VSP3210 consist of three CCD channels

and a 16-bit A/D. Each channel (Red, Green, and Blue) has

its own 10-bit Offset and 6-bit Gain Adjustable Registers to

be programmed by the user. There is also an 8-bit Configu-

ration Register, on-chip, to program the different operation

modes. Those registers are shown in Table III.

ADDRESS

A2 A1 A0

POWER-ON

DEFAULT VALUE

0 00

0 01

0 10

0 11

1 00

1 01

1 10

1 11

Configuration Register (8-bit)

Red Channel Offset Register (10-bit)

Green Channel Offset Register (10-bit)

Blue Channel Offset Register (10-bit)

Red Channel Gain Register (6-bit)

Green Channel Gain Register (6-bit)

Blue Channel Gain Register (6-bit)

Reserved

All â0sâ

TABLE III. On-Chip Registers.

These registers can be accessed by the following two pro-

gramming modes:

â¢ Parallel Programming Mode (VSP3200 only) using digi-

tal data output pins, with the data bus assigned as D0 to

D9 (pins 25 to 34), and the address bus as A0 to A2 (pins

35 to 37). It can be used for both reading and writing

operations. However, it cannot be used by the

Demultiplexed mode (when D7 of the Configuration

â¢ Serial Programming Mode using a serial port, Serial Data

(SD), the Serial Shift Clock (SCLK), and Write Signal

(WRT) assigned.

It can be used only for writing operations; reading opera-

tions via the serial port are prohibited.

Table IV shows how to access these modes (VSP3200 only).

P/S MODE

Digital data output enabled, Serial mode enabled

Prohibit mode (can not set this mode)

Digital data output disabled, Serial mode enabled

Digital data output disabled, Parallel mode enabled

TABLE IV. Access Mode for Serial and Parallel Port

(VSP3200 Only).

CONFIGURATION REGISTER

The Configuration Register design is shown in Table V.

BIT LOGIC â0â

LOGIC â1â

D0 CCD mode

VREF = 1V

D2 Internal Reference

D3 3-channel Mode,

D4 and D5 disabled

D4, D5 (disabled when 3-channel)

D7(1)

MUX Sequence

Red > Green > Blue

Normal output mode

CIS mode

VREF =1.5V

External Reference

1-channel Mode,

D4 and D5 enabled

D4 D5

0 0 1-channel mode, Red channel

0 1 1-channel mode, Green channel

1 0 1-channel mode, Blue channel

MUX Sequence

Blue > Green >Red

Demultiplexed output mode

NOTE: (1) D7 of the configuration register should always be set to â1â for the

VSP3210. Power-on default value is â0â; initial write operation for â1â is also

needed for the VSP3210, when in power-on.

TABLE V. Configuration Register Design.

Power-on default value is all â0sâ, set to 3-Channel CCD

mode with 1V internal reference, R > G > B MUX sequence,

and normal output mode.

For reading/writing to the Configuration Register, the ad-

dress will be A2 = â0â, A1 = â0â, and A0 = â0â.

For Example:

A 3-Channel CCD with internal reference VREF = 1V (2V

full-scale input), R > G > B sequence and normal output

mode will be D0 = â0â, D1 = â0â, D2 =â0â, D3 = â0â,

D4 = âx (donât care)â, D5 = âx (donât care)â, D6 = â0â, and

D7 = â0â.

For this example, bypass VREF with an appropriate capacitor

(e.g.:, 10ÂµF to 0.1ÂµF) when internal reference mode is used.

Another Example:

A 1-Channel CCD mode (Green channel) with an external

1.2V reference (2.4V full-scale input), Demultiplexed Out-

put mode will be D0 = â0â, D1 = âx (donât care)â, D2 = â1â,

D3 = â1â, D4 = â0â, D5 = â1â, D6 = âx (donât care)â, and

D7 = â1â.

For this example, VREF will be an input pin applied with 1.2V.

VSP3200, 3210

SBMS012A

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