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

Descriptors character

codes user definable

characters

1024 bytes

RAM

03FF

0400

Empty

Space

1FFF

2000

Character

Generator

ROM

32FF

3300

Empty

Space

3FFF

3FF0

Internal

Registers

3FFF

I.4 - Register Set

LINE DURATION

3FF0

-

-

LD5

LD4

LD3

LD2

LD1

LD0

*

-

-

11111

1

LD[5:0] : LINE DURATION (number of character

period, 1LSB = 12 pixel periods).

HORIZONTAL DELAY

3FF1

DD7 DD6 DD5 DD4 DD3 DD2 DD1 DD0

*

0

0

00100

0

DD[7:0] : HORIZONTAL DISPLAY DELAY from

the H-SYNC reference falling edge to

the 1

strips.

Unit = 3 pixel periods.

CHARACTERS HEIGHT

3FF2

-

-

CH5 CH4 CH3 CH2 CH1 CH0

*

-

-

01001

0

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 :

SLICE-NU MBER

=

round







SCAN

±LINE±NUMBER x 18

CH[5:0]







SCAN-LINE-NUMBER = Number of the current scan

line of the strip.

DISPLAY CONTROL

3FF3

OSD FBK

FL1

FL0

-

P8

P7

P6

*

0

000

-

0

00

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 isactive onlyduring

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

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

*

0

010

-

0

10

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 ur i n g l o c ki n g

conditions.

BS[2:0] : Frequency constant during locking

conditions.

CAPTURE PROCESS TIME CONSTANT

3FF5

-

AF2

AF1

AF0

-

BF2

BF1

BF0

*

-

011

-

0

11

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

*

0

01010

00

PP[7:0] : Value to initialize the pixel period of the

PLL.

FREQUENCY MULTIPLIER

3FF7

-

-

-

-

FM3 FM2 FM1 FM0

*

---

-

1

0

1

0

FM[3:0] : Frequency multiplier of the crystal

frequency to reach the high frequency

used by the PLL to derive the pixel

frequency.

STV9420 - STV9421

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