mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 378

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

Functional description
16.4 Functional description
This on-chip peripheral module is called a low leakage wakeup unit (LLWU) module
because it allows internal peripherals and external input pins as a source of wakeup from
low leakage modes. It is operational only in LLS and VLLSx modes.
The LLWU module contains pin enables for each external pin and internal module. For
each external pin, the user can disable or select the edge type for the wakeup. Type
options are falling, rising, or either edge. When an external pin is enabled as a wakeup
source, the pin must be configured as an input pin.
The LLWU implements optional 3-cycle glitch filters, based on the LPO clock, such that
a detected external pin (wakeup or RESET) is required to remain asserted until the
enabled glitch filter times out. Additional latency of up to 2 cycles is due to
synchronization, which results in a total of up to 5 cycles of delay before the detect
circuit alerts the system to the wakeup or reset event when the filter function is enabled.
Two wakeup detect filters are available to detect up to two external pins. A separate reset
filter is on the RESET pin. Glitch filtering is not provided on the internal modules.
For internal module wakeup operation, the WUMEx bit enables the associated module as
a wakeup source.
378
Reserved
RSTFILT
LLRSTE
Field
7–2
1
0
This read-only bitfield is reserved and always has the value zero.
Low Leakage mode RESET enable
This bit must be set to allow the device to be reset while in a low-leakage power mode. On devices where
Reset is not a dedicated pin, the RESET pin must also be enabled in the explicit port mux control.
0
1
Digital Filter on RESET Pin
Enables the digital filter for the RESET pin during LLS or VLLS mode.
0
1
RESET pin not enabled as a leakage mode exit source
RESET pin enabled as a low leakage mode exit source
Filter not enabled
Filter enabled
MCF51JF128 Reference Manual, Rev. 2, 03/2011
LLWU_RST field descriptions
Preliminary
Description
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