ST72314J4B7(2003) View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST72314J4B7
(Rev.:2003)

8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, ADC, 16-BIT TIMERS, SPI, SCI INTERFACES

STMicroelectronics 

ST72334J/N, ST72314J/N, ST72124J

POWER SAVING MODES (Cont’d)

11.3 WAIT MODE

WAIT mode places the MCU in a low power con-

sumption mode by stopping the CPU.

This power saving mode is selected by calling the

‘WFI’ instruction.

All peripherals remain active. During WAIT mode,

the I bit of the CC register is cleared, to enable all

interrupts. All other registers and memory remain

unchanged. The MCU remains in WAIT mode until

an interrupt or RESET occurs, whereupon the Pro-

gram Counter branches to the starting address of

the interrupt or Reset service routine.

The MCU will remain in WAIT mode until a Reset

or an Interrupt occurs, causing it to wake up.

Refer to Figure 21.

Figure 21. WAIT Mode Flow-chart

WFI INSTRUCTION

OSCILLATOR

PERIPHERALS

CPU

I BIT

ON

ON

OFF

0

N

RESET

N

Y

INTERRUPT

Y

OSCILLATOR ON

PERIPHERALS OFF

CPU

ON

I BIT

0

4096 CPU CLOCK CYCLE

DELAY

OSCILLATOR ON

PERIPHERALS ON

CPU

ON

I BIT

X 1)

FETCH RESET VECTOR

OR SERVICE INTERRUPT

Note:

1. Before servicing an interrupt, the CC register is

pushed on the stack. The I bit of the CC register is

set during the interrupt routine and cleared when

the CC register is popped.

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