參數(shù)資料
型號: STV9420
廠商: 意法半導(dǎo)體
英文描述: MULTISYNC ON-SCREEN DISPLAY FOR MONITOR
中文描述: 多頻屏幕的監(jiān)視器顯示
文件頁數(shù): 12/16頁
文件大?。?/td> 228K
代理商: STV9420
FUNCTIONAL DESCRIPTION
(continued)
VI - User Definable Character
The STV9420/21 allows the user to dynamically
define character(s)for his ownneeds(fora special
LOGO for example). Like the ROM characters, a
UDC is made of a 12 pixelsx 18 slices dot matrix,
but one more slice is added for the vertical shad-
owing when several UDCs are gatheredto makea
special greatcharacter (see Figure 8).
In a UDC,each pixel is defined with a bit,1 refers
to foreground, and 0 to background color. Each
slice of aUDC uses 2 bytes:
add + 1
-
-
-
-
PX11 PX10 PX9 PX8
add
(even)
PX11is the left most pixel. Characterslice address:
SLICEADDRESS=38x(CHARACTERNUMBER)
+ (SLICE NUMBER).
Where :
- CHARACTER NUMBER is the number given by
the character code,
- SLICE NUMBER isthe number givenbythe slice
interpolator (n
°
of the current slice of the strip :
1 < <18)
PX7 PX6 PX5 PX4 PX3
PX2 PX1 PX0
VII - ROM Character Generator
The STV9420/21includes a ROM character gen-
erator which is made of 128 alphanumeric or
graphic characters (seeTable 1)
VIII - PLL
The PLL function of the STV9420/21provides the
internalpixelclocklockedonthehorizontalsynchro
signal and usedby thedisplay processorto gener-
ate theR,G,Bandfast blanckingsignals.Itismade
of 2 PLLs. The first one analogic (see Figure 9),
provides a high frequency signal locked on the
crystal frequency.The frequencymultiplieris given
by :
N = 2
(FM[3:0] + 3)
Where FM[3:0] is the value of the FREQUENCY
MULTIPLIER register.
FILTRE
%N
F
XTAL
VCO
N.F
XTAL
9
Figure 9 :
AnalogicPLL
ALGO
%M
F
H-SYNC
%D
M.F
H-SYNC
err(n)
D(n)
N.F
XTAL
9
Figure 10 :
Digital PLL
The second PLL, full digital (see Figure 10), pro-
vides a pixel frequency locked on the horizontal
synchrosignal. The ratio between the frequencies
of these 2 signalsis :M = 12 x (LD[5:0] + 1)
Where LD[5:0]is the value of the LINEDURATION
register.
VIII.1- Programmingof the PLL Registers
Frequency Multiplier
(@3FF7)
This register gives the ratio between the crystal
frequency and the high frequency of the signal
usedbythe2
nd
PLLtoprovide,bydivision,thepixel
clock. The value of this high frequency must be
near to 200MHz (for example if the crystal is a
8MHz, the value of FM must be equal to 10) and
greater than 6 x (pixelfrequency).
Initial Pixel Period
(@3FF6)
This register allows to increase the speed of the
convergence of the PLL when the horizontal fre-
quencychanges(new graphic standart).The rela-
tionshipbetweenFM[3:0],PP[7:0],LD[5:0],F
HSYNC
and F
XTAL
is :
PP[7:0]
=
round
Locking Condition Time Constant
(@3FF4)
This register gives the constants AS[2:0] and
BS[2:0]usedbythealgopart ofthePLL(seeFigure
10) to calculate, from the phase error, err(n), the
new value, D(n), of the division of the high fre-
quencysignalto providethepixel clock.These two
constantsare used onlyin locking condition,which
is true, if the phase error is less thana fixed value
during at least, 4 scan lines. If The phase error
becomes greater than the fixed value, the PLL is
not in locking condition but in capture process. In
this case, the algo part of the PLLused the other
constants, AF[2:0] and BF[2:0], given by the next
register.
Capture ProcessTime Constant
(@ 3FF5)
The choice between these two time constants
(locking condition or capture process) allows to
decreasethecaptureprocesstime bychangingthe
time responseof the PLL.
8
2
(
FM[3:0]
+
3
)
F
XTAL
12
LD[5:0]
F
HSYNC
±
24
STV9420 - STV9421
12/16
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