MC68HC05X4 Datasheet, PDF (114/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
16-Bit Programmable Timer
prescaler, the value in the free-running counter repeats every 262144
internal bus clock cycles. TOF is set when the counter overflows (from
$FFFF to $0000); this will cause an interrupt if TOIE is set.
Bits 8 – 15 — MSB of counter/alternate counter register
A read of only the more significant byte (MSB) transfers the LSB to a
buffer, which remains fixed after the first MSB read, until the LSB is also
read.
Bits 0 – 7 — LSB of counter/alternate counter register
A read of only the less significant byte (LSB) receives the count value at
the time of reading.
Timer functions
The 16-bit programmable timer is monitored and controlled by a group
of ten registers, full details of which are contained in the following
paragraphs. An explanation of the timer functions is also given.
Timer control
register (TCR)
The timer control register ($12) is used to enable the input capture
(ICIE), output compare (OCIE), and timer overflow (TOIE) interrupt
enable functions as well as selecting input edge sensitivity (IEDG) and
output level polarity (OLVL).
Address: $0012
Bit 7
6
5
4
3
2
1
Bit 0
ICIE OCIE TOIE
0
0
0
IEDG OLVL
Reset: 0
0
0
0
0
0
u
0
Figure 6. Timer Control Register (TCR)
MC68HC05X4 Rev 1.0
16-Bit Programmable Timer
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6-ptimer