4

* This specification are subject to be changed without notice.

7.20.1999

EM73201

4-BIT MICRO-CONTROLLER FOR GENERAL PURPOSE PRODUCT

Preliminary

FUNCTION DESCRIPTIONS

PROGRAM ROM ( 2K X 8 bits )

2 K x 8 bits program ROM contains user's program and some fixed data .

The basic structure of program ROM can be divided into 5 parts.

1. Address 000h: Reset start address.

2. Address 002h - 00Ch: 4 kinds of interrupt service rountine entry addresses .

3. Address 00Eh-086h : SCALL subroutine entry address, only available at 00Eh,016h,01Eh,026h, 02Eh,

036h, 03Eh, 046h, 04Eh, 056h, 05Eh, 066h, 06Eh, 076h ,07Eh, 086h .

4. Address 000h - 7FFh : LCALL subroutine entry address

5. Address 7E0h - 7FFh : The data region for 5-to-8 bits data conversion table .

6. Address 000h - 7FFh : Except used as above function, the other region can be used as user's program region.

address

2048 x 8 bits

000h

Reset start address

002h

INT0; External interrupt service routine entry address

004h

006h

TRGA, Timer/counterA interrupt service routine entry address

008h

00Ah

TBI; Time base interrupt service routine entry address

00Ch

INT1; External interrupt service routine entry address

00Eh

086h

7FFh

User's program and fixed data are stored in the program ROM. User's program is according the PC value

to send next executed instruction code. Fixed data can be read out by two ways.

(1) Table-look-up instruction:

Table-look-up instruction is depended on the Data Pointer ( DP ) to indicate to ROM address, then to get

the ROM code data.

LDAX

Acc ←

←

←

←

← ROM[DP]

L

LDAXI

Acc ←

←

←

←

← ROM[DP]

DP is a 12-bit data register which can store the program ROM address to be the pointer for the ROM

code data. First, user load ROM address into DP by instruction "STADPL, STADPM, STADPH",

then user can get the lower nibble of ROM code data by instruction "LDAX" and higher nibble by

instruction "LDAXI".

PROGRAM EXAMPLE: Read out the ROM code of address 777h by table-look-up instruction.

LDIA #07h;

STADPL

; [DP]

STADPM ; [DP]

STADPH

; [DP]

:

LDL #00h;

LDH #03h;

LDAX

; ACC ← 6h

..

.

..

.

SCALL, subroutine call entry address