LSI

LS3321

2

Functional Description

1. RC Oscillator /Crystal

The LS3321 can use either a crystal oscillator or RC oscillator to provide the internal timing by

bonding option.

2. Program ROM

The LS3321 has internal 3Kx12 bit ROM providing simple operation. It has six internal stacks.

The program ROM is page-segmented with 1K per page. To access pages higher than 1K, use the

CALL instruction. The CALL instruction jumps to the address defined by ROMPAGE.jjjjjjjjjj where

jjjjjjjjjj is specified in the CALL instruction.

3. Interrupt Control

The LS3321 has 5 different sources of interrupt, namely, POWERUP, F4HZ, F16HZA, F16HZS and

F1HZ. The starting address of the interrupt are as follow :

Interrupt

Address

POWERUP

0x3ff

F1HZ

0x3fe

F4HZ

0x3fc

F16HZA

0x3f8

F16HZS

0x3f1

The system generates 16 interrupts for F16HZS in one second but only 11 interrupts for F16HZA.

The other 5 interrupts goes to F4HZ (4) and F1HZ (1) interrupts.

4. Program RAM

The system has 128x4bit of program RAM (00H to 7fH) with IO address as follows.

Address

Description

Initialize

0H

RptrL

undefined

1H

RptrH

undefined

2H

Rptr1L

undefined

3H

Rptr1H

undefined

4H

Beep Control

0

5H

ROM PAGE

0

6H

RAM PAGE

0

7H

No use

0

8H

IOP0

IO[0:3]

9H

IOP1

IO[4:7]

AH

IOP2

IO[8:11]

BH

IOP3

INP[0:3]

CH(read)

Timer 1 Value

-

CH(write)

Timer 1 Data

-

DH(write)

Timer 1 Control

0

FH(write)

COM/OUTPUT (XXX0/XXX1)

XXX0

10H-3FH

SYSTEM RAM

-

40H-7FH

DISPLAY RAM

-

80H-AFH

SYSTEM RAM

-