ST72344K2 datasheet(69/247 Pages) STMICROELECTRONICS

69 / 247 page

ST72344xx, ST2345xx

Power-saving modes

Doc ID 12321 Rev 6

69/247

Note:

As soon as active halt is enabled, executing a HALT instruction while the Watchdog is active

does not generate a reset. This means that the device cannot spend more than a defined

delay in this power saving mode.

Figure 30.

Active-halt timing overview

Figure 31.

Active-halt mode flowchart

Note:

This delay occurs only if the MCU exits Active-Halt mode by means of a reset.

Peripheral clocked with an external clock source can still be active.

Only the RTC interrupt and some specific interrupts can exit the MCU from Active-halt mode

(such as external interrupt). Refer to Table 17 for more details.

Before servicing an interrupt, the CC register is pushed on the stack. The I[1:0] bits in the

CC register are set to the current software priority level of the interrupt routine and restored

when the CC register is popped.

halt

Run

256 OR 4096 cycle

delay (after reset)

Reset

interrupt

HALT

instruction

Fetch

vector

Active-

(Active-halt enabled)

HALT INSTRUCTION

RESET

INTERRUPT 3)

CPU

OSCILLATOR

PERIPHERALS 2)

I[1:0] BITS

OFF

FETCH RESET VECTOR

OR SERVICE INTERRUPT

CPU

OSCILLATOR

PERIPHERALS

I[1:0] BITS

OFF

XX 4)

CPU

OSCILLATOR

PERIPHERALS

I[1:0] BITS

XX 4)

256 OR 4096 CPU CLOCK

CYCLE DELAY

(MCCSR.OIE=1)

(AWUCSR.AWUEN=0)

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