ST72F264G ST Microelectronics, ST72F264G Datasheet - Page 34

• Manufacturer Part Number: ST72F264G
• Description: (ST72F260G - ST72F264G) 8-BIT MCU
• Manufacturer: ST Microelectronics

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ST72260G, ST72262G, ST72264G
POWER SAVING MODES (Cont’d)
8.3 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 [1:0] bits in the CC register are forced to ‘10b’ ,
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 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
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Figure
23.
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Figure 23. WAIT Mode Flowchart
Note:
1. Before servicing an interrupt, the CC register is
pushed on the stack. The I[1:0] bits in the CC reg-
ister are set during the interrupt routine and
cleared when the CC register is popped.
WFI INSTRUCTION
N
INTERRUPT
Y
OR SERVICE INTERRUPT
FETCH RESET VECTOR
4096 CPU CLOCK CYCLE
OSCILLATOR
PERIPHERALS
CPU
I[1:0] BITS
OSCILLATOR
PERIPHERALS
CPU
I[1:0] BITS
OSCILLATOR
PERIPHERALS
CPU
I[1:0] BITS
N
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DELAY
RESET
Y
XX
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
0
1
1)
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