PCB8517 Datasheet, PDF (12/24 Pages) NXP Semiconductors – Stand-alone OSD for monitor applications

Philips Semiconductors
Stand-alone OSD for monitor applications
Objective specification
PCB8517
Character ROM
The character ROM contains 128 character fonts. Each
font consists of a 12 × 16 dot matrix.
Bordering and shadowing of characters
The characters displayed on the screen can be specified
with or without shadowing or with border shadowing by
setting the BSEN and SHSE bits of frame control register
“Column 11 of row 10”. If shadowing is specified, there is
black shadow on the right and bottom sides of character,
and if border shadowing is specified, the black shadowing
will surround both internal and external sides of characters
(see Fig.5). The characters shadow will not appear if it is
outside the display area of character (i.e. 12 × 16 dots).
PLL clock generator
By tracing the signal on the HFLB pin, the on-chip PLL
circuit generates the clock (VCLK) which is used for both
system clock and dot clock of the OSD. The frequency of
VCLK signal is determined by following equation:
f_VCLK = f_HFLB × 384 (i.e. the frequency range of VCLK
signal is from 3.84 to 38.4 MHz).
When there is no horizontal sync pulse present on the
HFLB pin, the PLL circuit will generate a 2.5 MHz
(approximate) clock for the system clock, and the RED,
GREEN, BLUE and FB pins will be high impedance.
Combination of two or more character fonts to
formulate a new symbol
User can combine two (or more) character fonts to
formulate a new higher resolution symbol in a horizontal
direction, but the combination of two fonts in a vertical
direction could cause the shadowing or bordering shadow
of upper font to be missed if shadowing or bordering is
applied.
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no shadow
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shadowing
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bordering shadow
MGD759
1997 Mar 03
Fig.5 Character shadowing and bordering.
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