MC68HC08AZ32A Datasheet, PDF (135/456 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Clock Generator Module (CGM)
CGM Registers
To check the status of the crystal reference, do the following:
1. Write a logic 1 to XLD.
2. Wait N × 4 cycles. N is the VCO frequency multiplier.
3. Read XLD.
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.
Bits 3–0 — Reserved for Test
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 bits 3–0 when writing to PBWC.
8.6.3 PLL Programming Register
The PLL programming register contains the programming information for
the modulo feedback divider and the programming information for the
hardware configuration of the VCO.
Address: $001E
Bit 7
6
5
4
3
2
1
Read:
MUL7
Write:
MUL6
MUL5
MUL4
VRS7
VRS6
VRS5
Reset: 0
1
1
0
0
1
1
Figure 8-6. PLL Programming Register (PPG)
Bit 0
VRS4
0
MUL7–MUL4 — Multiplier Select Bits
These read/write bits control the modulo feedback divider that selects
the VCO frequency multiplier, N. (See Circuits on page 121 and
Programming the PLL on page 125). A value of $0 in the multiplier
select bits configures the modulo feedback divider the same as a
value of $1. Reset initializes these bits to $6 to give a default multiply
value of 6.
MC68HC08AZ32A — Rev 1.0
MOTOROLA
Clock Generator Module (CGM)
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Technical Data
135