GMS81508B HYNIX [Hynix Semiconductor], GMS81508B Datasheet - Page 69

• Manufacturer Part Number: GMS81508B
• Description: HYUNDAI MICRO ELECTRONICS 8-BIT SINGLE-CHIP MICROCONTROLLERS
• Manufacturer: HYNIX [Hynix Semiconductor]

GMS81508B/16B/24B
18. POWER DOWN OPERATION
GMS815xxB has a power-down mode. In power-down
mode, power consumption is reduced considerably that in
battery operation. Battery life can be extended a lot.
18.1 STOP Mode
For applications where power consumption is a critical
factor, device provides reduced power of STOP.
Start The Stop Operation
An instruction that STOP causes to be the last instruction
is executed before going into the STOP mode. In the Stop
mode, the on-chip main-frequency oscillator is stopped.
With the clock frozen, all functions are stopped, but the on-
chip RAM and Control registers are held. The port pins
output the values held by their respective port data register,
the port direction registers. The status of peripherals during
Stop mode is shown below.
66
CPU
RAM
X
X
Oscillation
I/O ports
Control Registers
Release method
IN
OUT
PIN
Peripheral
PIN
External Interrupt
Internal Clock
BIT Counter
Oscillator
(X
IN
pin)
All CPU operations are disabled
Retain
Low
High
Stop
Retain
Retain
by RESET, by External interrupt
Figure 18-1 STOP Mode Release Timing by External Interrupt
Normal Operation
n
STOP Mode
n+1 n+2
STOP Instruction
Executed
Stop Operation
n+3
Before executing Stop instruction, Basic Interval Timer must be set
properly by software to get stabilization time which is longer than 20ms.
STOP Mode is entered by STOP instruction.
Note: Since the X
avoid current leakage due to the crystal oscillator in STOP
mode, do not use STOP instruction when an external clock
is used as the main system clock.
In the Stop mode of operation, V
imize power consumption. Be careful, however, that V
is not reduced before the Stop mode is invoked, and that
V
Stop mode is terminated.
The reset should not be activated before V
its normal operating level, and must be held active long
enough to allow the oscillator to restart and stabilize.
And after STOP instruction, at least two or more NOP in-
struction should be written as shown in example below.
Example:
The Interval Timer Register CKCTLR should be initial-
ized (0F
bilization time should be longer than 20ms before STOP
mode.
DD
is restored to its normal operating level before the
H
Clear
or 0E
LDM
STOP
NOP
NOP
:
0
H
t
by software
ST
1
) by software in order that oscillation sta-
IN
CKCTLR,#0000_1110B
20ms
pin is connected internally to GND to
HYUNDAI MicroElectronics
FE
FF
DD
DEC. 1999 Ver 1.04
can be reduced to min-
0
Normal Operation
DD
1
is restored to
2
DD