STR720 datasheet(72/401 Pages) STMICROELECTRONICS

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STR720 - WAKE-UP INTERRUPT UNIT (WIU)

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8.3.1

Interrupt Mode Selection.

To configure the 16 lines as interrupt sources, use the following procedure:

•

Configure the mask bits of the 16 wake-up lines (WUMR);

•

Configure the triggering edge register of the wake-up lines (WUTR);

•

Set properly the enable and mask bits corresponding to the line of interrupt controller tied

to Wake-up Unit: so an interrupt coming from one of the 16 lines can be correctly

acknowledged;

•

Reset the WKUP-INT bit in the WUCTRL register to disable Wake-up Mode (default value

is 0);

•

Set the INT_EN bit in the WUCTRL register to enable the 16 wake-up lines as external

interrupt source lines.

8.3.2

Wake-up Mode Selection

To configure the 16 lines as wake-up sources, use the following procedure:

•

Set the mask bits of the 16 wake-up lines (WUMR).

•

Configure the triggering edge register of the wake-up lines (WUTR).

•

Set the enable and the mask bits corresponding to the line of Interrupt Controller tied to

Wake-up Unit (as for Interrupt Mode selection), only if an interrupt routine is to be

executed after a wake-up event. Otherwise, if the wake-up event only restarts the

execution of the code from where it was stopped, the interrupt channel shall be masked.

•

Set the WKUP-INT bit in the WUCTRL register to select Wake-up Mode.

•

Set the INT_EN bit in the WUCTRL register to enable the 16 wake-up lines as external

interrupt source lines. This is not mandatory if the wake-up event does not require an

interrupt response.

•

Write the sequence 1,0,1 to the STOP bit of WUCTRL. This is the STOP bit setting

sequence. Pay attention that the three write operations are effective even though not

executed in a strict sequence (intermediate instructions are allowed, except for write

instructions to the registers of Wake-Up). If the sequence is not completed within 64 clock

periods (system clock), a TIMEOUT expires and reset the sequence. In this case the

software shall re-enter the sequence (1, 0, 1). To reset the sequence it is sufficient to write

twice a logic ‘0’ to the STOP bit of WUCTRL register (corresponding anyway to a bad

sequence).

To detect if STOP Mode was entered or not, immediately after the last STOP bit setting of the

sequence, poll the STOP bit itself (WUCTRL register).

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