STV9420 Просмотр технического описания (PDF) - STMicroelectronics

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STV9420

MULTISYNC ON-SCREEN DISPLAY FOR MONITOR

STMicroelectronics 

STV9420 - STV9421

FUNCTIONAL DESCRIPTION (continued)

The last fourth registers described below are only

available with the STV9421 :

PULSE WIDTH MODULATOR 1

3FF8 V17 V16 V15 V14 V13 V12 V11 V10

*

00000000

V1[7:0] : Digital value of the 1st PWM D to A

converter (Pin1).

PULSE WIDTH MODULATOR 2

3FF9 V27 V26 V25 V24 V23 V22 V21 V20

*

00000000

V2[7:0] : Digital value of the 2d PWM DAC (Pin11).

PULSE WIDTH MODULATOR 3

3FFA V37 V36 V35 V34 V33 V32 V31 V30

*

00000000

V3[7:0] : Digital value of the 3rd PWM DAC

(Pin20).

PULSE WIDTH MODULATOR 4

3FFB V47 V46 V45 V44 V43 V42 V41 V40

*

00000000

V4[7:0] : Digital value of the 4th PWM DAC

(Pin10).

Note : * is power on reset value.

II - Descriptors

SPACING

MSB 0 - - - - - - -

LSB SL7 SL6 SL5 SL4 SL3 SL2 SL1 SL0

SL[7:0] : The number of the scan lines of the

spacing strip (1 to 255).

CHARACTER

MSB 1 DE - ZY - - C9 C8

LSB C7 C6 C5 C4 C3 C2 C1 0

C[9:0] : The address of the first character code of

the strip (even).

DE : Display enable :

- DE = 0, R = G = B = 0 and FBLK = FBK

(display control register) on whole strip,

- DE = 1, display of the characters.

ZY : Zoom, ZY = 1 all the scan lines are

repeated once.

III - Code Format

MSB SET

CHARACTER NUMBER

LSB BK3 BK2 BK1 BK0 FL RF GF BF

FL : Flashing attribute (the flashing mode is

defined in the DISPLAY CONTROL register).

8/16

SET

: The set CHARACTER NUMBER

- If SET = 0 : ROM character,

- If SET = 1 :

• If CHARACTER NUMBER is 0 to

25, a user redefinable character

(UDC) located in RAM at the

address equal to : 38 x

CHARACTER NUMBER,

• If CHARACTER NUMBER is 26 to

63, space character,

• If CHARACTER NUMBER >63,

end of line.

RF, GF, BF : Foreground color.

BK[3:0]

: Background :

- If BK3 = 0, BK[2:0] = background

color R, G and B,

- If BK3 = 1, shadowing :

• BK2 : vertival shadowing,

• BK1 : horizontal shadowing.

(if BK2 = BK1 = 0, the background is

transparent).

IV - Clock and Timing

The whole timing is derived from the XTALIN and

the SYNCHRO (horizontal and vertival) input fre-

quencies. The XTALIN input frequency can be an

external clock or a crystal signal thanks to

XTALIN/XTALOUT pins. The value of this fre-

quency can be chosen between 8 and 15MHz, it is

available on the CKOUT pin and is used by the PLL

to generate a pixel clock locked on the horizontal

synchro input signal.

IV.1 - Horizontal Timing

The number of pixel periods is given by the LINE

DURATION register and is equal to :

[LD[5:0] + 1 ] x 12

(LD[5:0] : value of the LINE DURATION register).

This value allows to choose the horizontal size of

the characters.

The horizontal left margin is given by the HORI-

ZONTAL DELAY register and is equal to :

[DD[7:0] + 8] x 3 x tPXCK

(DD[7:0] : value of the DISPLAY DELAY register

and TPXCK : pixel period).

This value allows to choose the horizontal position

of the characters on the screen. The value of

DD[7:0] must be equal or greater than 4 (the mini-

mum value of the horizontal delay is 36 x tPXCK = 3

character periods). The length of the active area,

where R, G, B are different from 0, depends on the

number of characters of the strips.

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