VS6624P0LP datasheet(12/100 Pages) STMICROELECTRONICS

12 / 100 page

System architecture

VS6624

12/100

Rev 1

Output formatter

This module controls the embedded codes which are inserted into

the data stream to allow the host system to synchronize with the output data. It also controls

the optional HSYNC and VSYNC output signals.

3.3

Microprocessor functions

The microprocessor inside the VS6624 performs the following tasks:

Host communication handles the I²C communication with the host processor.

Video pipe configuration configures the video pipe modules to produce the output

required by the host.

Automatic exposure control In normal operation the VS6624 determines the appropriate

exposure settings for a particular scene and outputs correctly exposed images.

Flicker cancellation The 50/60Hz flicker frequency present in the lighting (due to

fluorescent lighting) can be cancelled by the system.

Automatic white balance The microprocessor adjusts the gains applied to the individual

color channels in order to achieve a correctly color balanced image.

Frame rate control

VS6624 contains a firmware based programmable timing generator.

This automatically designs internal video timings, PLL multipliers, clock dividers etc. to

achieve a target frame rate with a given input clock frequency.

Optionally an automatic frame rate controller can be enabled. This system examines the

current exposure status, integration time and gain and adapts the frame rate based on that.

This function is typically useful in low-light scenarios where reducing the frame rate extends

the useful integration period. This reduces the need for the application of analog and digital

gain and results in better quality images.

Dark calibration

The microprocessor uses information from special dark lines within

the pixel array to apply an offset to the video data and ensure a consistent ‘black’ level.

Active noise management The microprocessor is able to modify certain video pipe

functions according to the current exposure settings determined by the automatic exposure

controller. The main purpose of this is to improve the noise level in the system under low

lighting conditions. Functions which ‘strength’ is reduced under low lighting conditions (e.g.

sharpening) are controlled by ‘dampers’. Functions which ‘strength’ is increased under low

lighting conditions are controlled by ‘promoters’. The fade to black operation is also

controlled by the microprocessor

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