MC68HC708XL36 FREESCALE [Freescale Semiconductor, Inc], MC68HC708XL36 Datasheet - Page 101

• Manufacturer Part Number: MC68HC708XL36
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

19-cgm1m_a
MOTOROLA
ACQ — Acquisition Mode Bit
XLD — Crystal Loss Detect Bit
PBWC[3:0] — Reserved for Test
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.
When the VCO output, CGMVCLK, is driving CGMOUT, this
read/write bit can indicate whether the crystal reference frequency is
active or not.
To check the status of the crystal reference, do the following:
The crystal loss detect function works only when the BCS bit is set,
selecting CGMVCLK to drive CGMOUT. When BCS is clear, XLD
always reads as logic 0.
These bits enable test functions not available in user mode. To
ensure software portability from development systems to user
applications, software should write 0s to PBWC[3:0] whenever writing
to PBWC.
Freescale Semiconductor, Inc.
1.
2.
3.
For More Information On This Product,
1 = Tracking mode
0 = Acquisition mode
1 = Crystal reference not active
0 = Crystal reference active
Write a logic 1 to XLD.
Wait N
Read XLD.
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4 cycles. (N is the VCO frequency multiplier.)
CGM
MC68HC708XL36
CGM Registers
CGM
101