ST10R272L - POWER REDUCTION MODES
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POWER REDUCTION MODES
The ST10R272L has two power reduction modes - ‘Idle Mode’ and’ Power Down mode’.
•
Idle Mode: the CPU is stopped, but the peripherals continue operation. Idle Mode can
be terminated by any reset or interrupt request.
•
Power down mode: both the CPU and the peripherals are stopped. Power Down mode
can only be terminated by a hardware reset in protected mode, or by an external
interrupt.
Note
All external bus actions are completed before Idle or Power Down mode is entered.
However, Idle or Power Down mode is not entered if READY/READY is enabled, but
has not been activated (driven high/low) during the last bus access.
17.1
Idle Mode
The power consumption of the ST10R272L microcontroller can be decreased by entering
Idle Mode. In this mode all peripherals, including the Watchdog Timer, continue to operate
normally, only the CPU operation is halted.
Idle Mode is entered AFTER the IDLE instruction has been executed, AND the instruction
before IDLE has completed all stages of the pipeline. This guarantees that all instructions
before the IDLE instruction are completed before the CPU is stopped.
The IDLE instruction is a protected 32-bit instruction. This prevents unintentional entry into
Idle Mode.
Idle Mode is terminated by interrupt requests from any enabled interrupt source whose
individual Interrupt Enable Flag was set before the Idle Mode was entered, regardless of bit
IEN.
For a CPU interrupt service, the associated interrupt service routine is entered if the priority
level of the requesting source is higher than the current CPU priority, AND the interrupt
system is globally enabled. After the RETI (Return from Interrupt) instruction of the interrupt
service routine is executed, the CPU executes the instruction following the IDLE instruction.
If the interrupt request cannot be serviced (if the priority is too low or if the interrupt system