Interrupt/General-Purpose I/O Pin Descriptions

NOTE

The low-power interrupt control register (LPICR) in the System Control Module specifies the interrupt level at or above which is needed to bring the device out of a low-power mode.

Table 11-1. Edge Port Module Operation in Low-power Modes

Low-power Mode

EPORT Operation

 

 

 

 

Mode Exit

 

 

 

 

 

Wait

Normal

Any

 

Interrupt at or above level in LPICR

IRQx

 

 

 

 

 

Doze

Normal

Any

 

 

Interrupt at or above level in LPICR

IRQx

 

 

 

 

 

Stop

Level-sensing Only

Any

 

 

 

Interrupt set for level-sensing at or above

IRQx

 

 

level in LPICR

 

 

 

 

 

 

 

In wait and doze modes, the EPORT module continues to operate as it does in run mode. It may be configured to exit the low-power modes by generating an interrupt request on either a selected edge or a low level on an external pin. In stop mode, there are no clocks available to perform the edge-detect function. Only the level-detect logic is active (if configured) to allow any low level on the external interrupt pin to generate an interrupt (if enabled) to exit stop mode.

NOTE

The input pin synchronizer is bypassed for the level-detect logic since no clocks are available.

11.3 Interrupt/General-Purpose I/O Pin Descriptions

All pins default to general-purpose input pins at reset. The pin value is synchronized to the rising edge of CLKOUT when read from the EPORT pin data register (EPPDR). The values used in the edge/level detect logic are also synchronized to the rising edge of CLKOUT. These pins use Schmitt triggered input buffers which have built in hysteresis designed to decrease the probability of generating false edge-triggered interrupts for slow rising and falling input signals.

When a pin is configured as an output, it is driven to a state whose level is determined by the corresponding bit in the EPORT data register (EPDR). All bits in the EPDR are high at reset.

11-2

MCF5282 User’s Manual

MOTOROLA

Page 248
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Motorola MCF5282, MCF5281 Interrupt/General-Purpose I/O Pin Descriptions, Edge Port Module Operation in Low-power Modes