MC68HC05P18 Datasheet, PDF (96/144 Pages) Freescale Semiconductor, Inc – Advance Information

16-Bit Timer
Freescale Semiconductor, Inc.
Advance Information
96
the application software, a timer interrupt flag (TOF) could
unintentionally be cleared if:
1. The TSR is read when bit 5 (TOF) is set.
2. The LSB of the free-running counter is read, but not for the
purpose of servicing the flag or interrupt.
The alternate counter registers (ACRH and ACRL) contain the same
values as the timer registers (TMRH and TMRL). Registers ACRH and
ACRL can be read at any time without affecting the timer overflow flag
(TOF) or interrupt.
Address: $0013
Bit 7
6
5
4
3
2
1
Bit 0
Read: ICF
OCF
TOF
0
0
0
0
0
Write:
Reset: U
U
U
0
0
0
0
0
= Unimplemented U = Unaffected
Figure 10-11. Timer Status Register (TSR)
ICF — Input Capture Flag
Bit 7 is set when the edge specified by IEDG in register TCR has been
sensed by the input capture edge detector fed by pin TCAP. This flag
and the input capture interrupt can be cleared by reading register TSR
followed by reading the LSB of the input capture register pair (ICRL).
OCF — Output Compare Flag
Bit 6 is set when the contents of the output compare registers match
the contents of the free-running counter. This flag and the output
compare interrupt can be cleared by reading register TSR followed by
writing the LSB of the output compare register pair (OCRL).
TOF — Timer Overflow Flag
Bit 5 is set by a rollover of the free-running counter from $FFFF to
$0000. This flag and the timer overflow interrupt can be cleared by
reading register TSR followed by reading the LSB of the timer register
pair (TMRL).
MC68HC(8)05P18 — Rev. 2.0
16-Bit Timer
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