STV0974 datasheet(7/69 Pages) STMICROELECTRONICS

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Functional description

STV0974

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Functional description

4.1

Overview

The processor includes a chain of dedicated video data processing blocks controlled by a

microprocessor. The processing blocks perform the main video pipe processing while the

microprocessor manages the interactions between the sensor, the functional blocks and the host.

The host controls and monitors the STV0974 via a set of read/write registers accessible via the I2C

interface for the streaming video mode and via the asychronous microprocessor interface for the

microprocessor mode.

In video mode, the processor streams video data in a format which closely follows the data format

specified in the ITU-R656 standard.

In microprocessor mode, the video data is stored in a small FIFO before is it pulled out of the

asynchronous microprocessor interface by the host system (with DMA support).

4.1.1

Video pipe block description

Please refer to the block diagram (

Figure 1).

Sensor interface This block decodes the incoming serial data stream from the sensor (raw bayer

data) and converts it into a parallel form for the processing chain.

Video processor The video processor converts the raw bayer data from the sensor to RGB or

YUV processed data by applying a number of filters to the data then scaling and converting the

data into either one of the RGB modes or into YUV mode.

Video JPEG compressor The video compressor converts the processed data from the video

processor and converts the data into JPEG format. The compression ratio applied to the image can

be controlled by the microprocessor.

Streaming video output port In streaming video mode the data from either the video processor

or the video compressor is enclosed in a format which closely follows the data format specified in

the ITU-R656 standard.

Microprocessor interface In microprocessor interface mode, the data from the video processor or

video compressor is stored in a FIFO. The interface informs the system via an IRQ or a DRQ that

the FIFO is filling up. The system then has to pull some of the data from the STV0974 via the

microprocessor interface.

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