MC68HC705P9 Datasheet, PDF (104/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Timer _{I/O Registers}
Input Capture
Registers
When a selected edge occurs on the TCAP pin, the current high and low
bytes of the 16-bit counter are latched into the read-only input capture
registers (ICRH and ICRL). Reading ICRH before reading ICRL inhibits
further captures until ICRL is read. Reading ICRL after reading the timer
status register clears the input capture flag (ICF). Writing to the input
capture registers has no effect.
$0014 Bit 7
6
5
4
3
2
1
Bit 0
Read: Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
Unaffected by reset
$0015 7
6
5
4
3
2
1
0
Read: Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
Unaffected by reset
= Unimplemented
Figure 16. Input Capture Registers (ICRH and ICRL)
NOTE:
To prevent interrupts between readings of ICRH and ICRL, set the
interrupt mask (I bit) in the condition code register before reading ICRH,
and clear the mask after reading ICRL.
16-tim1ic1oc_a
104
Timer
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