MC908GR8CDWE Datasheet, PDF (99/408 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Freescale Semiconductor, Inc.
Technical Data — MC68HC908GR8
Section 7. Clock Generator Module (CGMC)
7.1 Contents
7.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
7.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
7.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
7.5 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
7.6 CGMC Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
7.7 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.8 Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.9 Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . .125
7.2 Introduction
This section describes the clock generator module. The CGMC
generates the crystal clock signal, CGMXCLK, which operates at the
frequency of the crystal. The CGMC also generates the base clock
signal, CGMOUT, which is based on either the crystal clock divided by
two or the phase-locked loop (PLL) clock, CGMVCLK, divided by two. In
user mode, CGMOUT is the clock from which the SIM derives the
system clocks, including the bus clock, which is at a frequency of
CGMOUT/2. In monitor mode, PTC3 determines the bus clock. The PLL
is a fully functional frequency generator designed for use with crystals or
ceramic resonators. The PLL can generate an 8-MHz bus frequency
using a 32-kHz crystal.
MC68HC908GR8 — Rev 4.0
MOTOROLA
Clock Generator Module (CGMC)
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Technical Data
99