µ
PD75512
20
V
DD
V
DD
XT1
XT2
X1
X2
f
XT
f
X
Watch timer
Subsystem
clock
oscillator
Main system
clock
oscillator
1/2 1/16
1/8 to 1/4096
Frequency divider
· Basic interval timer (BT)
· Timer/event counter
· Serial interface
· Watch timer
· Clock output circuit
· A/D converter
· INT0 noise rejecter circuit
Internal bus
WM.3
SCC
SCC3
SCC0
PCC
PCC0
PCC1
PCC2
PCC3
HALT*
STOP*
4
PCC2, PCC3
clear signal
STOP F/F
Q
S
R
Q
S
R
HALT F/F
Oscillator
disable
signal
Frequency
divider
1/4
Selector
Selector
Φ
· CPU
· INT0 noise
rejecter circuit
· Clock output
circuit
Wait release
signal from BT
RESET signal
Standby release
signal from interrupt
control circuit
Timer/pulse
generator
6.2
CLOCK GENERATOR CIRCUIT
The operation of the clock generator circuit is determined by the processor clock control regiser (PPC) and
system clock control register (SCC).
This circuit can generate two types of clocks: main system clock and subsystem clock.
In addition, it can also change the instruction execution time.
•
0.95
µ
s, 1.91
µ
s, 15.3
µ
s (main system clock: 4.19 MHz)
•
122
µ
s (subsystem clock: 32.768 kHz)
*: instruction execution.
Remarks 1: f
X
= Main system clock frequency
2: f
XT
= Subsystem clock frequency
3:
Φ =
CPU clock
4: PCC: Processor clock control register
5: SCC: System clock control register
6: One clock cycle (t
CY
) of
Φ
is one machine cycle of an instruction. For t
CY
, refer to AC
characteristics in 11. ELECTRICAL SPECIFICATIONS.
Fig. 6-1 Clock Generator Block Diagram
★
Содержание mPD75512
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