9

Electrical Description

Pin Function

Description

RESET (RST, pin 1)

Initializes the display.

FLASH (FL, pin 2)

FL low indicates an access to the Flash RAM and is unaffected by the

ADDRESS INPUTS

select a specific location in the Character RAM, the Flash RAM or a

used to select which section of memory is accessed. Table 1 shows the

logic levels needed to access each section of memory.

Table 1. Logic Levels to Access Memory

Section of Memory

FL

Flash RAM

0

X

X

Char. Address

UDC Address Register

1

0

0

Don't Care

UDC RAM

1

0

1

Row Address

Control Word Register

1

1

0

Don’t Care

Character RAM

1

1

1

Character Address

CLOCK SELECT

Used to select either an internal (CLS = 1) or external (CLS = 0) clock source.

(CLS, pin 11)

CLOCK INPUT/OUTPUT

Outputs the master clock (CLS = 1) or inputs a clock (CLS = 0) for slave

(CLK, pin 12)

displays.

WRITE (WR, pin 13)

Data is written into the display when the WR input is low and the

CE input is low.

CHIP ENABLE (CE, pin 17)

Must be at a logic low to read or write data to the display and must go

high between each read and write cycle.

READ (RD, pin 18)

Data is read from the display when the RD input is low and the CE

input is low.

Used to read from or write to the display.

pins 19, 20, 23-28)

GND (SUPPLY) (pin 15)

Analog ground for the LED drivers.

GND (LOGIC) (pin 16)

Digital ground for internal logic.

Positive power supply input.