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MSP430F6659 - how sleep/wakeup works?

Hi,

I have simple question but I can't find answer in documentation. Probably I search wrongly.

Please tell me if I enter uC to LPM3 and RTC works in sleep and generate interrupt every 1 min, than if I don't do "exit to LPM0" in interrupt than uC goes to sleep again after interrupt handling.

In which mode uC is wake up to handle RTC interrupt? All clocks and peripherials are woken up?

Regards,

  • The low-power modes are controlled by bits in the status register.

    What happens during an interrupt is specified in section 1.3.4.1 of the User's Guide:

    All bits of SR are cleared except SCG0, thereby terminating any low-power mode.

    (SCG0 controls the FLL; i.e., in an interrupt handler, the DCO does not try to adjust its frequency.)

    On a return from interrupt (section 1.3.4.2),

    the SR with all previous settings pops from the stack. All previous settings of GIE, CPUOFF, etc. are now in effect, regardless of the settings used during the interrupt service routine.

    The "exit to LPM0" would clear the LPM bits in the copy of the SR stored on the stack.

  • Thanks, good explanation.

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