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ST92141 - INTERRUPTS

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

3.12.5 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 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 STOP bit is at

1 in the two following cases (See “Wake-up Mode

Selection” on page 56. 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)

WARNING: Writing the sequence 1,0,1 to the

STOP bit will enter STOP mode only if no other

sequence. If Interrupt or DMA requests (which al-

ways perform register write operations) are ac-

knowledged during the sequence, the ST9 will not

enter STOP mode: the user must re-enter the se-

quence to set the STOP bit.

WARNING: Whenever a STOP request is issued

to the MCU, a few clock cycles are needed to enter

STOP mode (see RCCU chapter for further de-

tails). Hence the execution of the instruction fol-

lowing the STOP bit setting sequence might start

before entering STOP mode: if such instruction

performs a register write operation, the ST9 will

not enter in STOP mode. In order to avoid to exe-

cute register write instructions after a correct

STOP bit setting sequence and before entering

the STOP mode, it is mandatory to execute 3 NOP

instructions after the STOP bit setting sequence.

Bit 1 = ID1S:

Interrupt Channel INTD1 Source.

This bit is set and cleared by software.

0: INT7 external interrupt source selected, exclud-

ing wake-up line interrupt requests

1: The 16 external wake-up lines enabled as inter-

rupt sources, replacing the INT7 external pin

function

WARNING: To avoid spurious interrupt requests

on the INTD1 channel due to changing the inter-

rupt source, do the following before modifying the

ID1S bit:

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

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

2. Program the ID1S bit as needed.

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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