GMS81604 View Datasheet(PDF) - Hyundai Micro Electronics

Part Name

Description

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GMS81604

LG Semicon. CMOS single-chip 8-bit microcontroller. ROM size 8K bytes. 256 bytes of on-chip data RAM

Hyundai Micro Electronics 

GMS81604/08

LG Semicon

RESET

The reset input is the RESET pin, which is the input to

a Schmitt Trigger. A reset in accomplished by holding

the RESET pin low for at least 8 oscillator periods,

while the oscillator running. After reset, 64ms (at 8

MHz) plus 7 oscillator periods are required to start

execution as shown in Figure 40.

Internal RAM is not affected by reset. When VDD is

turned on, the RAM content is indeterminate. Initial

state of each register is as follow. Therefore, this RAM

should be initialized before reading or testing it.

EX) 5V OPERATION

+5V

RESET

10KΩ

7042

+

10uF

4.2V RESET IC

Figure 39. Example of Reset circuit

Register

A

X

Y

PSW

PC

SP

R0

R0DD

R1

R1DD

R4

R4DD

R5

R5DD

R6

R6DD

PMR4

PMR5

BITR

CKCTLR

WDTR

TM0

TM2

TDR0/ T0/ CDR0

TDR1/ T1/ CDR1

TDR2/ T2/ CDR2

TDR3/ T3/ CDR3

ADCM

ADR

BUR

PFDR

IENH

IENL

IRQH

IRQL

IEDS

- = unimplemented bit

X= unknown

Content

X

X

X

00H

X

X

X

00000000

X

00000000

X

00000000

X

--0---00

X

00000000

00000000

--0-----

00H

--010111

-0111111

00H

00H

X

X

X

X

--000001

X

X

-----100

00H

000-----

00H

000-----

00H

OSCILLATOR

1

2

3

4

5

6

7

RESET

ADDRESS BUS

DATA BUS

?

?

tST = 64 ms

at 8 MHz

STABILIZATION TIME

?

?

?

FFFE FFFF Start

?

?

?

FE ADL ADH OP Code

RESET PROCESS STEP

MAIN PROGRAM

Figure 40. Timing Diagram after Reset

44

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