MC68HC705J1ACPE Datasheet, PDF (111/162 Pages) Freescale Semiconductor, Inc – Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.
Multifunction Timer Module
Operation
Addr. Register Name
Bit 7
6
5
Read: TOF
RTIF
Timer Status and Control
TOIE
$0008
Register (TSCR) Write:
See page 112.
Reset: 0
0
0
$0009
Timer Counter Register ^Read:
(TCR)
See page 114.
Write:
Reset:
TMR7
0
TMR6
0
TMR5
0
= Unimplemented
4
RTIE
0
TMR4
0
3
0
TOFR
0
TMR3
0
Figure 9-2. I/O Register Summary
2
0
RTIFR
0
TMR2
0
1
RT1
1
TMR1
0
Bit 0
RT0
1
TMR0
0
9.3 Operation
A 15-stage ripple counter, preceded by a prescaler that divides the
internal clock signal by four, provides the timing reference for the timer
functions. The value of the first eight timer stages can be read at any
time by accessing the timer counter register at address $0009. A timer
overflow function at the eighth stage allows a timer interrupt every 1024
internal clock cycles.
The next four stages lead to the real-time interrupt (RTI) circuit. The RT1
and RT0 bits in the timer status and control register at address $0008
allow a timer interrupt every 16,384, 32,768, 65,536, or 131,072 clock
cycles. The last four stages drive the selectable COP system. For
information on the COP, refer to the Section 7. Computer Operating
Properly (COP) Module.
MC68HC705J1A — Rev. 4.0
Multifunction Timer Module
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Technical Data