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µPD750008 USER'S MANUAL
5.2 CLOCK GENERATORThe clock generator supplies various clock signals to the CPU and peripheral hardware to control the CPUoperation mode.5.2.1 Clock Generator ConfigurationFigure 5-11 shows the configuration of the clock generator.Figure 5-11. Block Diagram of the Clock GeneratorNote Instruction executionRemarks 1. fX: Main system clock frequency2. fXT: Subsystem clock frequency3. F = CPU clock4. PCC: Processor clock control register5. SCC: System clock control register6. One clock cycle (tCY) of the CPU clock (F) is equal to one machine cycle of an instruction.
Subsystem 
clock generator
Main system 
clock generator
Clock timer
• Basic interval timer (BT)
• Timer/event counter
• Timer counter
• Serial interface
• Clock timer
• INT0 noise eliminator
• Clock output circuit
1/1 to 1/4096
Frequency divider
Selec-
tor
Selec-
tor
Frequency 
divider
Φ
Oscillator 
disable 
signal
Internal bus
HALT
Note
STOP
Note
PCC2, PCC3 
clear signal Wait release signal from BT
Standby release signal from 
interrupt control circuit
RESET signal
XT1
XT2
X1
X2
4
SCC
SCC3
SCC0
PCC
PCC0
PCC1
PCC2
PCC3
STOP flip-flop
QS
R
HALT flip-flop
S
Q
R
f
XT
f
X
1/2 1/16
1/4
1/4
CPU
INT0 noise eliminator
Clock output circuit
WM.3