Rev. 1.0, 02/00, page 173 of 1141
Section 9 Clock Pulse Generator
9.1
Overview
This LSI has a built-in clock pulse generator (CPG) that generates the system clock (
φ
), the bus
master clock, and internal clocks.
The clock pulse generator consists of a system clock oscillator, a duty adjustment circuit, clock
selection circuit, medium-speed clock divider, subclock oscillator, and subclock division circuit.
9.1.1
Block Diagram
Figure 9.1 shows a block diagram of the clock pulse generator.
System
clock
oscillator
Duty
adjustment
circuit
Clock
selection
circuit
Medium-
speed clock
divider
Subclock
oscillator
Subclock
division
circuit
OSC1
OSC2
X1
X2
φ
/16,
φ
/32,
φ
/64
φ
w/2,
φ
w/4,
φ
w/8
φ
SUB
φ
or
φ
SUB
Timer A
count clock
Internal clock
To supporting modules
Bus master clock
To CPU
φ
SUB (
φ
w/2,
φ
w/4,
φ
w/8)
Figure 9.1 Block Diagram of Clock Pulse Generator
9.1.2
Register Configuration
The clock pulse generator is controlled by SBYCR and LPWRCR. Table 9.1 shows the register
configuration.
Table 9.1
CPG Registers
Name
Abbreviation
R/W
Initial Value
Address
*
Standby control register
SBYCR
R/W
H'00
H'FFEA
Low-power control register
LPWRCR
R/W
H'00
H'FFEB
Note:
*
Lower 16 bits of the address.