ASX340CS datasheet(41/74 Pages) ONSEMI

41 / 74 page

ASX340CS_DS Rev. F Pub. 6/15 EN

©Semiconductor Components Industries, LLC, 2015.

ASX340CS: 1/4-Inch Color CMOS NTSC/PAL Digital Image Sensor

Overlay Capability

Figure 23 highlights the graphical overlay data flow of theASX340CS. The images are

separated to fit into 2KB blocks of memory after compression.

• Up to four overlays may be blended simultaneously

• Overlay size 360 x 480 pixels rendered into a display area of 720 x 480 pixels (NTSC) or

720 x 576 (PAL)

• Selectable readout: rotating order is user programmable

• Dynamic movement through predefined overlay images

• Palette of 32 colors out of 64,000 with eight colors per bitmap

• Blend factors may be changed dynamically to achieve smooth transitions

The host commands allow a bitmap to be written piecemeal to a memory buffer through

the I2C, and also through DMA direct from SPI Flash memory. Multiple encoding passes

may be required to fit an image into a 2KB block of memory; alternatively, the image can

be divided into two or more blocks to make the image fit. Every graphic image may be

positioned in an x/y direction and overlap with other graphic images.

The host may load an image at any time. Under control of DMA assist, data are trans-

ferred to the off-screen buffer in compressed form. This assures that no display data are

corrupted during the replenishment of the four active overlay buffers.

Figure 23:

Overlay Data Flow

Note:

These images are not actually rendered, but show conceptual objects and object blending.

Off-screen

buffer

Overlay buffers: 2KB each

Decompress

Blend and Overlay

Flash

Bitmaps - compressed

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