MC68HC05E5 Datasheet, PDF (57/140 Pages) Freescale Semiconductor, Inc – General Release Specification

Freescale Semiconductor, Inc.
Timer
Timer Counter Register
8.4 Timer Counter Register
The timer counter register (TCR) is a read-only register which contains
the current value of the 8-bit ripple counter at the beginning of the timer
chain. This counter is clocked at f_op divided by four and can be used for
various functions including a software input capture. Extended time
periods can be attained using the TOF function to increment a temporary
RAM storage location, thereby simulating a 16-bit (or more) counter.
Address: $0009
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset: 0
0
0
0
0
0
1
1
= Unimplemented
Figure 8-3. Timer Counter Register (TCR)
The power-on cycle clears the entire counter chain and begins clocking
the counter. After 4064 cycles, the power-on reset circuit is released
which again clears the counter chain and allows the device to come out
of reset. At this point, if RESET is not asserted, the timer will start
counting up from zero and normal device operation will begin. When
RESET is asserted any time during operation other than POR, the
counter chain will be cleared.
MC68HC05E5 — Rev. 1.0
General Release Specification
Timer
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