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3.5 TIMERS
3-34
The MC68302 includes three timer units: two identical general-purpose timers
and a watchdog timer.
Each general-purpose timer consists of a timer mode register (TMR), a timer
capture register (TCR), a timer counter (TCN), a timer reference register (TRR),
and a timer event register (TER). The TMR contains the prescaler value pro-
grammed by the user. The watchdog timer, which has a watchdog reference
register (WRR) and a watchdog counter (WCN), uses a fixed prescaler value.
The timer block diagram is shown in Figure 3-5.
TER1
EVENT REGISTER
TMR1
DIVIDER
TCN1
TRR1
TCR1
WATClflOG TIMER
TCN3
l
TRR3
l
TIMER COUNTER
REFERENCE REGISTER
CAPTURE REGISTER
!;c
c
TIMER COUNTER
r-
I
REFERENCE REGISTER
~
'If
r
]
I_
CAPTURE
DETECTION
DIVIDE BY
512
l
_r
Figure 3-5. Timer Block Diagram
MC68302 USER'S MANUAL
. .
~
INTERNAL
MASTER CLOCK/16
OR MASTER CLOCK/1
TIN1
TOUT1
INTERNAL
MASTER CLOCK/16
MOTOROLA
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