KS57C2308/P2308/C2316/P2316

POWER-DOWN

 

 

+PROGRAMMING TIP — Reducing Power Consumption for Key Input Interrupt Processing

The following code shows real-time clock and interrupt processing for key inputs to reduce power consumption. In this example, the system clock source is switched from the main system clock to a subsystem clock and the LCD display is turned on:

KEYCLK

DI

 

 

 

 

CALL

MA2SUB

;

Main system clock subsystem clock switch subroutine

 

SMB

15

 

 

 

LD

EA,#00H

 

 

 

LD

P2,EA

;

All key strobe outputs to low level

 

LD

A,#3H

 

 

 

LD

IMOD2,A

;

Select KS0–KS7 enable

 

SMB

0

 

 

 

BITR

IRQW

 

 

 

BITR

IRQ2

 

 

 

BITS

IEW

 

 

 

BITS

IE2

 

 

CLKS1

CALL

WATDIS

;

Execute clock and display changing subroutine

 

BTSTZ

IRQ2

 

 

 

JR

CIDLE

 

 

 

CALL

SUB2MA

;

Subsystem clock main system clock switch

subroutine

 

 

 

 

 

EI

 

 

 

 

RET

 

 

 

CIDLE

IDLE

 

;

Engage idle mode

 

NOP

 

 

 

 

NOP

 

 

 

 

NOP

 

 

 

 

JPS

CLKS1

 

 

NOTE

You must program at least three NOP instructions after IDLE and STOP instructions, to avoid flowing of leakage current due to the floating state in the internal bus.

8-5

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Image 203
Samsung KS57C2308 Keyclk Call MA2SUB, P2,EA, IMOD2,A, SMB Bitr Irqw IRQ2 Bits IEW IE2 CLKS1 Call Watdis, RET Cidle Idle