ade3700 STMicroelectronics, ade3700 Datasheet - Page 63

• Manufacturer Part Number: ade3700
• Description: Analog Lcd Display Engine For Xga And Sxga Resolutions
• Manufacturer: STMicroelectronics

ADE3700
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Character Display
There are two 96-character monochrome fonts and two 32-character four-bit color fonts, a total of
256 characters. The four bits of color are an index into one of two 16 entry color lookup tables.
Entries in the color lookup table specify a 24-bit RGB color. All fonts and the color look-up table are
RAM-based and must be downloaded to the OSD’s internal RAM before use. Font addressing is as
follows: character indexes 0x00-0x1F refer to color font 0, 0x20-0x7F refer to monochrome font 0,
0x80-0x9F refer to color font 1 and 0xA0-0xFF refer to monochrome font 1.
Screen Map
The OSD uses a character map of 15 rows x 30 columns. Each character occupies one byte. The
value of each byte indicates the character to display.
The OSD character map is addressed by specifying the row and column as part of the data transfer.
Attribute Map
The attribute map is defined as 16 rows by 31 columns. It has an extra row and an extra column
compared to the screen map.
The values corresponding to printable row/column addresses provide character attributes. Each
character on the screen has an attribute byte specifying (in the case of monochrome fonts) three
bits of background color, four bits of foreground color, and a blink on/off bit.
Blinking, when enabled, has a period of 100 frames (50 frames on, 50 frames off).
Column 31 of each row contains row attributes. These include the fourth bit of the background color
and two bits controlling double-height and double-width text.
Row 15 contains global attributes, including vertical and horizontal OSD position on the screen,
alpha blending, shadow/bordering, OSD rotation, color map selection, and normal/double size.
Alpha blending allows the OSD display to be mixed with the incoming video signal for transparency
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wa = window attributes
ga = global attributes
wa
Figure 9: Character Attribute Map
Character Attributes
ga
wa
ga
wa
On-Screen Display (OSD)
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