STV9420 Datasheet, PDF (7/16 Pages) STMicroelectronics – MULTISYNC ON-SCREEN DISPLAY FOR MONITOR

STV9420 - STV9421
FUNCTIONAL DESCRIPTION (continued)
I.3 - Addressing Space
STV9420/21registers, RAM and ROM are mapped
in a 16Kbytes addressing space. The mapping is
the following :
0000
03FF
0400
1FFF
2000
32FF
3300
3FFF
3FF0
3FFF
1024 bytes
RAM
Empty
Space
Character
Generator
ROM
Empty
Space
Internal
Registers
Descriptors character
codes user definable
characters
I.4 - Register Set
LINE DURATION
3FF0 - - LD5 LD4 LD3 LD2 LD1 LD0
*
- - 111111
LD[5:0] : LINE DURATION (number of character
period, 1LSB = 12 pixel periods).
HORIZONTAL DELAY
3FF1 DD7 DD6 DD5 DD4 DD3 DD2 DD1 DD0
*
00001000
DD[7:0] : HORIZONTAL DISPLAY DELAY from
the H-SYNC reference falling edge to
the 1^st pixel position of the character
strips.
Unit = 3 pixel periods.
CHARACTERS HEIGHT
3FF2 -
*
-
- CH5 CH4 CH3 CH2 CH1 CH0
- 010010
CH[5:0] : HEIGHT of the character strips in scan
lines. For each scan line, the number of
the slice which is displayed is given by :
S LI CE -NU M BER
=
round
SCAN±LINE±NUMBER


CH[5:0]
x
18


SCAN-LINE-NUMBER = Number of the current scan
line of the strip.
DISPLAY CONTROL
3FF3 OSD FBK FL1 FL0 -
*
0000 -
P8 P7 P6
000
OSD : ON/OFF (if 0, R, G, B and FBLK are 0).
FBK : Fast blanking control :
= 1 : FBLK = 1, forcing black where
these is no display,
= 0 : FBLK is active only during
character display.
FL[1:0] : Flashing mode :
- 00 : No flashing. The character
attribute is ignored,
- 01 : 1/1 flashing (a duty cycle = 50%),
- 10 : 1/3 flashing,
- 11 : 3/1 flashing.
P[8:6] : Address of the 1^st descriptor of the
current displayed pages.
P[13:9] and P[5:0] = 0 ; up to 8 different
pages can be stored in the RAM.
LOCKING CONDITION TIME CONSTANT
3FF4 FR AS2 AS1 AS0 - BS2 BS1 BS0
*
0010 - 010
FR : Free Running ; if = 1 PLL is disabled and
the pixel frequency keeps its last value.
AS[2:0] : Ph a s e co n st a n t d urin g lo c kin g
conditions.
BS[2:0] : Frequency constant during locking
conditions.
CAPTURE PROCESS TIME CONSTANT
3FF5 - AF2 AF1 AF0 - BF2 BF1 BF0
*
- 011 - 011
AF[2:0] : Phase constant during the capture
process.
BF[2:0] : Frequency constant during the capture
process.
INITIAL PIXEL PERIOD
3FF6 PP7 PP6 PP5 PP4 PP3 PP2 PP1 PP0
*
00101000
PP[7:0] : Value to initialize the pixel period of the
PLL.
FREQUENCY MULTIPLIER
3FF7 - - - - FM3 FM2 FM1 FM0
*
-
-
- - 1010
FM[3:0] : Frequency multiplier of the crystal
frequency to reach the high frequency
used by the PLL to derive the pixel
frequency.
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