Panasonic MN101C77C, F77G user manual Transition between Slow and Normal

Models: F77G MN101C77C

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Chapter 2 CPU Basics

2-4-3 Transition between SLOW and NORMAL

This LSI has two CPU operating modes, NORMAL and SLOW. Transition from SLOW to NORMAL requires passing through IDLE mode.

A sample program for transition from NORMAL to SLOW mode is given below.

Program 1

 

 

MOV

x'3', D0

; Set SLOW mode.

MOV

D0, (CPUM)

 

 

 

 

Transition from NORMAL to SLOW mode, when the low-frequency clock has fully stabilized, can be done by writing to the CPU mode control register. In this case, transition through IDLE is not needed.

For transition from SLOW to NORMAL mode, the program must maintain the idle state until high-fre- quency clock oscillation is fully stable. In IDLE mode, the CPU operates on the low-frequency clock.

For transition from SLOW to NORMAL, oscillation stabilization waiting time is required same as that after reset. Software must count that time.

We recommend selecting the oscillation stabilization time after consulting with oscillator manufacturers.

Sample program for transition from SLOW to NORMAL mode is given below.

Program 2

 

 

 

 

MOV

x'01', D0

; Set IDLE mode.

 

MOV

D0, (CPUM)

 

 

 

 

 

 

 

 

 

Program 3

 

 

 

MOV

x'0B', D0

; A loop to keep approx. 6.7 ms with low-frequency clock (32 kHz)

LOOP ADD

-1, D0

; operation when changed to high-frequency clock (20 MHz).

BNE

LOOP

;

 

SUB

D0, D0

;

 

MOV

D0, (CPUM)

; Set NORMAL mode.

 

 

 

 

II- 22 Standby Functions

Page 74
Image 74
Panasonic MN101C77C, F77G user manual Transition between Slow and Normal