Datasheet

MC68HC908GP20 — Rev 2.1 Advance Information
Freescale Semiconductor 129
AUTO — Automatic Bandwidth Control Bit
This read/write bit selects automatic or manual bandwidth control.
When initializing the PLL for manual operation (AUTO = 0), clear the
ACQ bit before turning on the PLL. Reset clears the AUTO bit.
1 = Automatic bandwidth control
0 = Manual bandwidth control
LOCK — Lock Indicator Bit
When the AUTO bit is set, LOCK is a read-only bit that becomes set
when the VCO clock, CGMVCLK, is locked (running at the
programmed frequency). When the AUTO bit is clear, LOCK reads as
logic 0 and has no meaning. The write one function of this bit is
reserved for test, so this bit must always be written a 0. Reset clears
the LOCK bit.
1 = VCO frequency correct or locked
0 = VCO frequency incorrect or unlocked
ACQ — Acquisition Mode Bit
When the AUTO bit is set, ACQ
is a read-only bit that indicates
whether the PLL is in acquisition mode or tracking mode. When the
AUTO bit is clear, ACQ is a read/write bit that controls whether the PLL
is in acquisition or tracking mode.
In automatic bandwidth control mode (AUTO = 1), the last-written
value from manual operation is stored in a temporary location and is
recovered when manual operation resumes. Reset clears this bit,
enabling acquisition mode.
1 = Tracking mode
0 = Acquisition mode
Bit 7654321Bit 0
Read:
AUTO
LOCK
ACQ
0000
R
Write:
Reset:00000000
= Unimplemented R= Reserved
Figure 7-5. PLL Bandwidth Control Register (PBWC)