TMP88CU74F datasheet(15/132 Pages) TOSHIBA

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TMP88CU74

2003-02-17

88CU74-15

1.4.4

Operating Mode Control

(1) STOP mode (STOP1, STOP2)

STOP mode is controlled by the system control register 1 (SYSCR1) and the STOP

pin input. The STOP pin is also used both as a port P20 and an INT5 (external

interrupt input 5) pin. STOP mode is started by setting STOP (bit 7 in SYSCR1) to “1”.

During STOP mode, the following status is maintained.

Oscillations are turned off, and all internal operations are halted.

The data memory, registers, the program status word and port output latches are

all held in the status in effect before STOP mode was entered.

The prescaler and the divider of the timing generator are cleared to “0”.

The program counter holds the address of the instruction but one to the

instruction (e.g.[SET (SYSCR1).7]) which started STOP mode.

STOP mode includes a level-sensitive release mode and an edge-sensitive

release mode, either of which can be selected with the RELM (bit 6 in SYSCR1).

Level-sensitive release mode (RELM = “1”)

In this mode, STOP mode is released by setting the STOP pin high. This mode

is used for capacitor back-up when the main power supply is cut off and long term

battery back-up.

When the STOP pin input is high, executing an instruction which starts STOP

mode will not place in STOP mode but instead will immediately start the release

sequence (warm-up). Thus, to start STOP mode in the level-sensitive release mode,

it is necessary for the program to first confirm that the STOP pin input is low. The

following two methods can be used for confirmation.

Testing a port P20.

Using an external interrupt input INT5 ( INT5 is a falling edge-sensitive input).

Example 1: Starting STOP mode from NORMAL mode by testing a port P20.

(SYSCR1), 01010000B

;

Sets up the level-sensitive release mode

SSTOPH:

TEST

(P2). 0

;

Wait until the STOP pin input goes low

level

JRS

F, SSTOPH

SET

(SYSCR1). 7

;

Starts STOP mode

Example 2: Starting STOP mode from NORMAL mode with an INT5 interrupt.

PINT5:

TEST

(P2). 0

;

To reject noise, STOP mode does not

start if port P20 is at high

JRS

F, SINT5

(SYSCR1), 01010000B

;

Sets up the level-sensitive release mode.

SET

(SYSCR1). 7

;

Starts STOP mode

SINT5:

RETI

2007-10-19

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