HT1647

10

April 21, 2000

SE G 0

SE G 1

SE G 2

SE G 3

SE G 6 3

COM 1 4

COM 1 5

A ddr

511

7

23

31

COM 0

COM 1

D0

Da t a

A ddr

504

0

8

24

Da t a 4 B i t s

( D 3, D 2, D 1, D 0)

A ddr es s 9 B i t s

( A 8 , A 7 , .... , A 0 )

16

D1

D2

D3

Da t a

D0

D1

D2

D3

15

: T w o b i t s of R A M m ap t o LC D ' s one pi x e l and dec i de 4- l e v e l gr ay s c a l e

o r 4- c o l o r di s p l a y c onc ur r ent l y .

Display memory - RAM structure

Display memory - RAM structure

The static display RAM is organized into 512´4

bits and stores the display data. Two bits of

RAM map to Lad¢s one pixel and decide

whether 4-level gray scale or 4-color display

concurrently. The contents of the RAM are di-

rectly mapped to the contents of the LCD

driver. Data in the RAM can be accessed by the

READ, WRITE and READ-MODIFY-WRITE

commands. The following is a mapping from

the RAM to the LCD patterns.

Gray scale level decision

HT1647 uses PWM technique to provide 4-level

gray scale display. Two bits of RAM data code

((D3, D2) or (D1, D0)) decide one pixel level of

LCDs, level 1~level 4 dividedly. Every level

must be defined as one kind of gray scale by PWM

data (namely B4~B0) previously.

RAM data code

(D3, D2) or (D1, D0)

Choice Gray Scale

Level

(1, 1)

Level 1

(1, 0)

Level 2

(0, 1)

Level 3

(0, 0)

Level 4

RAM data defined gray scale level

Frame frequency

HT1647 provides two kinds frame frequency op-

tion by command code, 89Hz and 170Hz respec-

tively. FRAME 89Hz provides 89Hz frame

frequency and active segment signal width can be

divided into 24 sections concurrently. FRAME

170Hz provides 170Hz frame frequency and ac-

tive segment signal width can be divided into 13

sections concurrently. The 24 sections display a

particularly gray scale more than the 13 sections

by PWM data. The default is FRAME 89Hz.

Gray scale display

If the user choose 89Hz frame frequency, a max.

of 24 sections can be programmed to suit a sat-

isfactory gray scale in every level. Similarly, if

the user choose 170Hz frame frequency, a max.

of 13 sections can be programmed to suit a satis-