Clock Generator Module (CGM)
Functional Description
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Clock Generator Module (CGM) 113
8.4.2 Phase-Locked Loop Circuit (PLL)
The PLL is a frequency generator that can operate in either acquisition
mode or tracking mode, depending on the accuracy of the output
frequency. The PLL can change between acquisition and tracking
modes either automatically or manually.
8.4.2.1 PLL Circuits
The PLL consists of these circuits:
Voltage-controlled oscillator (VCO)
Modulo VCO frequency divider
Phase detector
Loop filter
Lock detector
Addr. Register Name Bit 7654321Bit 0
$005C PLL Control Register
(PCTL)
See page 124.
Read: PLLIE PLLF PLLON BCS 1111
Write: R R R R R
Reset:00101111
$005D PLL Bandwidth Control Register
(PBWC)
See page 126.
Read: AUTO LOCK ACQ XLD 0000
Write: R R R R R
Reset:00000000
$005E PLL Programming Register
(PPG)
See page 128.
Read: MUL7 MUL6 MUL5 MUL4 VRS7 VRS6 VRS5 VRS4
Write:
Reset:01100110
R=Reserved
Figure 8-2. CGM I/O Register Summary