ADE3000SXT STMicroelectronics, ADE3000SXT Datasheet - Page 67

• Manufacturer Part Number: ADE3000SXT
• Description: LCD Display Engines with Integrated DVI/ ADC and YUV Ports
• Manufacturer: STMicroelectronics

ADE3XXX
For information on OSD programming, see the OSD Programming Manual.
OSD Access via I2C
The OSD uses a dedicated memory space accessible through an I2C port. The data stream sent to
the OSD register starts with two header bytes. These specify the type of transfer and the row/
column position for screen map transfers, the character index for font definition transfers, or the
color index for color map transfers.
A stream of OSD writes to the OSD I2C register can fill in a segment of the OSD memory space with
an internal auto-incrementing index register. The protocol is as follows:
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 look-up tables.
Entries in the color look-up 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
1. Issue a start sequence with the R/W bit set to W.
2. Write to the OSD register. The first byte transferred is the index of the first internal OSD
3. Continue writing data bytes until the desired range of OSD internal registers has been written
4. Issue an I2C stop sequence.
Graphics character attributes: per-pixel color, vertical/horizontal mirroring
Row attributes: double width, double height
Window attributes: window visibility, position, size, border shadow, color table
Global attributes: OSD visibility, OSD screen position, alpha fade in/fade out, global size
doubling, rotation in ninety-degree increments
Single-bit enable/disable
register to be written. The next byte contains the data to be written to that register. Subsequent
bytes are written to successive internal OSD registers.
(the ADE3XXX device will issue an ACK on each transfer).
OSD Block
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