1997 Nov 21

15

Philips Semiconductors

Product specification

65

× 102 pixels matrix LCD driver

PCF8549

Table 2

Explanations for symbols in Table 1

External reset (RES)

After power-on a reset pulse has to be applied immediately to the chip, as it is in an undefined state. A reset of the chip

can be achieved with the external reset pin. After the reset the LCD driver is set to the following status:

• Power down mode (PD = 1)

• Read-modify-write mode is disabled (RM = 0)

• Horizontal addressing (V = 0)

• Normal instruction set (H = 0)

• Normal display (MX = MY = 0)

• Display blank (E = D = 0)

• Address counter X[6 : 0] = 0 and Y[3 : 0] = 0

• Temperature coefficient (TC[1 : 0] = 0)

• Bias system (BS[2 : 0] = 0)

• Read-modify-write mode disabled (RM = 0)

• After power-on, RAM data are undefined; The reset signal does not change the content of the RAM.

Set read-modify-write

When RM = 0, the read-modify-write mode is disabled. The X/Y-address counter is incremented after every read or write

access to the display data RAM.

When RM = 1, the read-modify-write mode is enabled. In this mode the X/Y-address is incremented only after a write

access to the display data RAM. The X/Y-address will not be incremented after a read access to the RAM.

BIT

0

1

RESET STATE

PD

chip is active

chip is in power down mode

1

V

horizontal addressing

vertical addressing

0

H

use basic instruction set

use extended instruction set

0

MX

normal X-addressing

X-address is mirrored

0

MY

display is not vertically mirrored

display is vertically mirrored

0

RM

read-modify-write mode is disabled read-modify-write mode is enabled 0

D and E

00

display blank

D = 0

E=0

10

normal mode

01

all display segments on

11

inverse video mode

TC[1 : 0] 00

TC[1 : 0] = 00

01

10

11

BS[2 : 0]

bias system

BS[2 : 0] = 000