Lucent Technologies MN102F85K User Manual

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This section describes the basic operation of the OSD block. The remainder of 

section 7 provides more detailed specifications.

The OSD clock source is programmable to either the microcontroller system 

clock (OSC1, OSC2 pins) or a dedicated OSD clock (OSDXI, OSDXO pins).

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See section 7.11, “Selecting the 

OSD Dot Clock,” on page 186, 
for information on setting the 

OSD clock frequency.

An internal phase-locked loop (PLL) multiplies the external 4-MHz frequency to 

generate an OSD clock that is synchronized to the trailing edge of the horizontal 
sync signal (HSYNC). This dramatically reduces EMI and character distortion. 

The output frequency is programmable to 12, 16, 24, 32 or 48 MHz.

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An LC blocking oscillator allows HSYNC to serve as the clock source. You can 
also input an external clock through the OSDXI pin and synchronize it internally. 

(Frequency range: 12–48 MHz)

Input the horizontal sync signal through the HSYNC pin and the vertical sync 

signal through the VSYNC pin. The pullup resistors and polarity are pro-
grammable. An interrupt must occur so that the microcontroller can detect each 

VSYNC start field. Set the interrupt edge in the IQ1TG[1:0] bits of the EXTMD 
registers and the OSD input polarity in the VPOL bit of the OSD1 register. Note 

that you must these parameters separately.

Multi-layer technology enables the microcontroller to display text, graphics, and 

hardware cursor as different display layers with different color depths. You can 
stack the layers in any order. When the layers contain overlapping images, the 

cursor always takes highest priority. The priority of the text and graphics layers is 
programmable in the registers.

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Do not layer any graphic or cur-
sor tiles over italicized charac-

ters in closed-caption mode.

Each character in the text layer contains a foreground (character) color and a 

background color. Outlining and shadowing are separate options. In closed-
caption mode, the OSD can only display the text in the encoded captions. The 

graphics and cursor layers can be displayed in this mode, but note that if any tiles 
from either layer overlaps italicized text, the pixels in the graphic will be dis-

placed, distorting the image.