GMS81504 Datasheet, PDF (42/54 Pages) List of Unclassifed Manufacturers – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

GMS81504
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 36.
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 35. Example of Reset circuit
HYUNDAI MicroElectronics
Register
A
X
Y
PSW
PC
SP
R0
R0DD
R4
R4DD
R5
R5DD
R6
R6DD
PMR4
PMR5
BITR
CKCTLR
TM0
TDR0/ T0/ CDR0
TDR1/ T1/ CDR1
ADCM
ADR
BUR
IENH
IENL
IRQH
IRQL
IEDS
- = unimplemented bit
X= unknown
Content
X
X
X
00H
X
X
X
00000000
X
00000000
X
000-----
X
0000----
-0-0--00
--0-----
00H
--010111
00H
X
X
--000001
X
X
00--00--
0-0-----
00--00--
0-0-----
-----000
OSCILLATOR
RESET
ADDRESS BUS
DATA BUS
42
1
2
3
4
5
6
7
?
?
tST = 64 ms
at 8 MHz
STABILIZATION TIME
?
?
?
FFFE FFFF Start
?
?
?
FE ADL ADH ^{OP Code}
RESET PROCESS STEP
MAIN PROGRAM
Figure 36. Timing Diagram after Reset