Functional Description

NOTE

Entering stop mode will disable the SDRAMC including the refresh counter. If SDRAM is used, then code is required to insure proper entry and exit from stop mode. See Section 7.3.2.5, “SDRAM Controller (SDRAMC)” for more information.

7.3.1.5Peripheral Shut Down

Most peripherals may be disabled by software in order to cease internal clock generation and remain in a static state. Each peripheral has its own specific disabling sequence (refer to each peripheral description for further details). A peripheral may be disabled at any time and will remain disabled during any low-power mode of operation.

7.3.2Peripheral Behavior in Low-Power Modes

7.3.2.1ColdFire Core

The ColdFire core is disabled during any low-power mode. No recovery time is required when exiting any low-power mode.

7.3.2.2Static Random-Access Memory (SRAM)

SRAM is disabled during any low-power mode. No recovery time is required when exiting any low-power mode.

7.3.2.3Flash

The Flash module is in a low-power state if not being accessed. No recovery time is required after exit from any low-power mode.

7.3.2.4System Control Module (SCM)

The SCM’s core Watchdog timer can bring the device out of all low-power modes except stop mode. In stop mode, all clocks stop, and the core Watchdog does not operate.

When enabled, the core Watchdog can bring the device out of low-power mode in one of two ways. If the core Watchdog reset/interrupt select (CSRI) bit is set, then a core Watchdog timeout will cause a reset of the device. If the CSRI bit is cleared, then a core Watchdog interrupt may be enabled and upon watchdog timeout, can bring the device out of low-power mode. This system setup must meet the conditions specified in Section 7.3.1, “Low-Power Modes” for the core Watchdog interrupt to bring the part out of low-power mode.

MOTOROLA

Chapter 7. Power Management

7-7

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Motorola MCF5281 Peripheral Behavior in Low-Power Modes, Peripheral Shut Down, ColdFire Core, System Control Module SCM