UPD75518 NEC, UPD75518 Datasheet - Page 51

• Manufacturer Part Number: UPD75518
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC

4.2 CLOCK GENERATOR
(1) Configuration of the clock generator
The clock generator supplies various clock signals to the CPU and peripheral hardware. Fig. 4-11 shows
the configuration of the clock generator.
Note Instruction execution
Remarks 1. f
HALT
STOP
4
Note
Note
PCC2, PCC3
clear signal
2. f
3. PCC : Processor clock control register
4. SCC: System clock control register
SCC3
SCC0
PCC0
PCC1
PCC2
PCC3
SCC
PCC
XT1
XT2
X1
X2
X
XT
: Main system clock frequency
: Subsystem clock frequency
Subsystem
clock generator
Main system
clock generator
Fig. 4-11 Block Diagram of the Clock Generator
Oscillator
disable
signal
STOP F/F
Q
f
f
XT
X
R
S
Clock timer
Timer/pulse
generator
1/2
1/4
1/16
Selec-
tor
Frequency divider
1/8 to 1/4096
HALT F/F
R
S
Selec-
tor
Q
Wait release signal from BT
Standby release signal from
interrupt control circuit
•
•
•
•
•
•
Basic interval timer (BT)
Timer/event counter
Serial interface
Clock timer
Clock output circuit
A/D converter
RESET signal
PD75518(A)
Frequency
divider
1/4
CPU
clock
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