ADE3700 datasheet(63/89 Pages) STMICROELECTRONICS

63 / 89 page

63/89

ADE3700

On-Screen Display (OSD)

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

Figure 9: Character Attribute Map

Character Attributes

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

wa = window attributes

ga = global attributes

ADE3700 数据表(PDF) 63 Page - STMicroelectronics