
S3C880A/F880A
ON-SCREEN DISPLAY
13-7
OSD Enable/Disable
The DSPCON.0 setting enables or disables the on-screen display module. To enable the OSD (turn L-C
oscillation on), set DSPCON.0 to "1"; to disable OSD (turn L-C oscillation off), clear DSPCON.0 to "0". When you
do not use the display module, we recommend that you keep DSPCON.0 cleared to "0" in order to reduce
possible noise generation by the L-C oscillator.
The DSPCON.0 settings determine the on/off condition of L-C oscillation, synchronized with Vsync input. And the
OSD output can be turned on or off in OSD row units when L-C oscillation is on. At the point the value of
DSPCON.0 is changed from “1” to “0” in the middle of a frame, OSD is disabled (OSD output is off). In this
condition, L-C oscillation becomes off at the next Vsync input. When the value is shifted from “0” to “1”, OSD is
enabled (OSD output is on) and L-C oscillation returns to “on” at the following Vsync input.
H-Sync and V-Sync Polarity Selection
DSPCON.3 selects the triggering edge of H-sync and V-sync inputs to the OSD block. Incoming sync pulses
enter a polarity option circuit that is controlled by the SYNC bit. If DSPCON.3 = "0", rising edges are selected; if
it is "1", falling edges are selected.
Character Halftone or Character Background Color Selection
DSPCON.2 and DSPCON.1 let you select a halftone or background color display for individual characters.
(Which characters are displayed as halftones, or with character background color, or with character halftone, or
with character background color, or with character halftone and background color, depends on the bit 13 settings
in the character video RAM data)
When DSPCON.2-.1 = "00", the character background color option is selected; when DSPCON.2-.1 = "10", the
character halftone function is selected; when DSPCON.2-.1 = "11", the character halftone and background color
option are selected; but DSPCON.2-.1 = "01" is not used.
ROW Counter Function
DSPCON.4–DSPCON.7 to the OSD ROW read data. OSD ROW counter indicates the OSD ROW currently
displayed. One ROW comprises one character (18 lines) and inter-ROW space (ROWCON.2–.0).
The Row counter value for the first ROW after a Vsync input is set to “0”.