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ST92F124/F150/F250 - INTERRUPTS

WAKE-UP / INTERRUPT LINES MANAGEMENT UNIT (Cont’d)

5.12.5 Register Description

WAKE-UP CONTROL REGISTER (WUCTRL)

R249 - Read/Write

Reset Value: 0000 0000 (00h)

Bit 2 = STOP: Stop bit.

To enter STOP Mode, write the sequence 1,0,1 to

this bit with three consecutive write operations.

When a correct sequence is recognized, the

STOP bit is set and the RCCU puts the MCU in

STOP Mode. The software sequence succeeds

only if the following conditions are true:

– The NMI pin is kept low,

– The WKUP-INT bit is 1,

– All unmasked pending bits are reset

– At least one mask bit is equal to 1 (at least one

external wake-up line is not masked).

Otherwise the MCU cannot enter STOP mode, the

program code continues executing and the STOP

bit remains cleared.

The bit is reset by hardware if, while the MCU is in

STOP mode, a wake-up interrupt comes from any

of the unmasked wake-up lines. The bit is kept

high if, during STOP mode, a rising edge on NMI

pin wakes up the ST9. In this case the user should

reset it by software. The STOP bit is at 1 in the four

following cases (See “Wake-up Mode Selection”

on page 114. for details):

– After the first write instruction of the sequence (a

1 is written to the STOP bit)

– At the end of a successful sequence (i.e. after

the third write instruction of the sequence)

– The ST9 entered and exited STOP mode due to

a rising edge on the NMI pin. In this case the

EX_STP bit in the CLK_FLAG is at 1 (see

RCCU chapter).

– The ST9 did not enter STOP mode due to the

NMI pin being kept high. In this case RCCU bit

EX_STP is at 0

Note: The STOP request generated by the

WUIMU (that allows the ST9 to enter STOP mode)

is ORed with the external STOP pin (active low).

This means that if the external STOP pin is forced

low, the ST9 will enter STOP mode independently

of the status of the STOP bit.

WARNINGS:

– Writing the sequence 1,0,1 to the STOP bit will

enter STOP mode only if no other register write

instructions are executed during the sequence. If

Interrupt or DMA requests (which always perform

ing the sequence, the ST9 will not enter STOP

mode: the user must re-enter the sequence to

set the STOP bit.

– Whenever a STOP request is issued to the MCU,

a few clock cycles are needed to enter STOP

mode (see RCCU chapter for further details).

Hence the execution of the instruction following

the STOP bit setting sequence might start before

entering STOP mode: if such instruction per-

forms a register write operation, the ST9 will not

enter in STOP mode. In order to avoid to execute

bit setting sequence and before entering the

STOP mode, it is mandatory to execute 3 NOP

instructions after the STOP bit setting sequence.

Refer to Section 13.2 on page 409.

Bit 1 = ID1S: Interrupt Channel INTD1 Source.

This bit is set and cleared by software.

It enables the 16 wake-up lines as external inter-

rupt sources. This bit must be set to 1 to enable

the wake-up lines.

WARNING: To avoid spurious interrupt requests

on the INTD1 channel due to changing the inter-

rupt source, use this procedure to modify the ID1S

bit:

1. Mask the INTD1 interrupt channel (bit 7 of reg-

ister EIMR - R244, Page 0 - reset to 0).

2. Set the ID1S bit.

3. Clear the IPD1 interrupt pending bit (bit 7 of

4. Remove the mask on INTD1 (bit EIMR.7=1).

Bit 0 = WKUP-INT: Wakeup Interrupt.

This bit is set and cleared by software.

0: The 16 external wakeup lines can be used to

generate interrupt requests

1: The 16 external wake-up lines to work as wake-

up sources for exiting from STOP mode

-----

STOP

ID1S

WKUP-INT

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