MC68HC812A4 Datasheet, PDF (154/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Clock Module
10.2 Introduction
Clock generation circuitry generates the internal and external E-clock
signals as well as internal clock signals used by the CPU and on-chip
peripherals. A clock monitor circuit, a computer operating properly
(COP) watchdog circuit, and a periodic interrupt circuit are also
incorporated into the MCU.
10.3 Block Diagram
XTAL
EXTAL
OSCILLATOR
REGISTER: CLKCTL
BITS:
BCS[C:B:A]
0:0:0
MUXCLK
SYSCLK
÷2
÷2
0:0:1
÷2
0:1:0
÷2
0:1:1
PLLS
÷2
1:0:0
÷2
1:0:1
PHASE-LOCK
LOOP
÷2
1:1:0
÷2
1:1:1
T-CLOCK
GENERATOR
TCLK
TO CPU
E- AND P-CLOCK
GENERATOR
ECLK
PCLK
REGISTER: CLKCTL
BITS:
MCS[B:A]
÷2
0:0
MCLK
÷2
0:1
TO BDM,
BUSES,
SPI,
ATD
TO SCI, TIM,
PA, RTI, COP
÷2
1:1
Figure 10-1. Clock Module Block Diagram
MC68HC812A4 — Rev. 3.0
154
Clock Module
Advance Information
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