Panasonic F77G CPU Mode Control Register, Operating Mode and Clock Oscillation Cpum x3F00, R/W

Models: F77G MN101C77C

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Chapter 2 CPU Basics

2-4-2 CPU Mode Control Register

Transition from one mode to another mode is controlled by the CPU mode control register (CPUM).

7

6

5

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2

1

0

CPUM

SOSCDBL OSCSEL1OSCSEL0 OSCDBL STOP HALT OSC1 OSC0

At reset :

0

0

0

0

0

0

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Status

 

Operation

STOP

HALT

OSC1

OSC0

OSC1

 

XI/XO

System

CPU

mode

/OSC0

 

clock

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NORMAL

0

0

0

0

 

Oscillation

Oscillation

OSCI

Operating

IDLE

0

0

0

1

 

Oscillation

Oscillation

XI

Operating

SLOW

0

0

1

1

 

Halt

Oscillation

XI

Operating

HALT0

0

1

0

0

 

Oscillation

Oscillation

OSCI

Halt

HALT1

0

1

1

1

 

Halt

Oscillation

XI

Halt

STOP0

1

0

0

0

 

Halt

 

Halt

Halt

Halt

STOP1

1

0

1

1

 

Halt

 

Halt

Halt

Halt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2-4-2 Operating Mode and Clock Oscillation (CPUM : x'3F00', R/W)

The procedure for transition from NORMAL to HALT or STOP mode is given below.

(1)If the return factor is a maskable interrupt, set the MIE flag in the PSW to "1" and set the interrupt mask (IM) to a level permitting acceptance of the interrupt.

(2)Clear the interrupt request flag (xxxIR) in the maskable interrupt control register (xxxICR) , set the interrupt enable flag (xxxIE) for the return factor, and set the IE flag in the PSW.

(3)Set CPUM to HALT or STOP mode.

Set the IRWE flag of the memory control register (MEMCTR) to clear interrupt request flag by software.

System clock (fs) is changed depending on CPU operation mode.

In NORMAL mode, HALT0 mode, fs is based on fosc (high speed oscillation). In SLOW mode, IDLE mode, HALT1 mode, fs is based on fx (low speed oscillation).

[

Chapter 2. 2-5 Clock Switching ]

Standby Functions

II - 21

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Panasonic F77G, MN101C77C user manual CPU Mode Control Register, Operating Mode and Clock Oscillation Cpum x3F00, R/W