ST72C104G2B7(2000_11) View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST72C104G2B7
(Rev.:2000_11)

8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, ADC, 16-BIT TIMERS, SPI, I2C INTERFACES

STMicroelectronics 

ST72104G, ST72215G, ST72216G, ST72254G

POWER SAVING MODES (Cont’d)

9.3 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” ST7 software instruction.

All peripherals remain active. During WAIT mode,

the I bit of the CC register is forced to 0, to enable

all interrupts. All other registers and memory re-

main unchanged. The MCU remains in WAIT

mode until an interrupt or Reset occurs, whereup-

on the Program 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 18.

Figure 18. 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

1

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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