MC908QY8CDWE Datasheet, PDF (186/232 Pages) Freescale Semiconductor, Inc – Addendum to MC68HC908QB8, rev. 3

Timer Interface Module (TIM)
effect. Therefore, a TOF interrupt request cannot be lost due to inadvertent clearing of TOF. Writing a
1 to TOF has no effect.
1 = Counter has reached modulo value
0 = Counter has not reached modulo value
TOIE — TIM Overflow Interrupt Enable Bit
This read/write bit enables TIM overflow interrupts when the TOF bit becomes set.
1 = TIM overflow interrupts enabled
0 = TIM overflow interrupts disabled
TSTOP — TIM Stop Bit
This read/write bit stops the counter. Counting resumes when TSTOP is cleared. Reset sets the
TSTOP bit, stopping the counter until software clears the TSTOP bit.
1 = Counter stopped
0 = Counter active
NOTE
Do not set the TSTOP bit before entering wait mode if the TIM is required
to exit wait mode. Also, when the TSTOP bit is set and the timer is
configured for input capture operation, input captures are inhibited until the
TSTOP bit is cleared.
When using TSTOP to stop the timer counter, see if any timer flags are set.
If a timer flag is set, it must be cleared by clearing TSTOP, then clearing the
flag, then setting TSTOP again.
TRST — TIM Reset Bit
Setting this write-only bit resets the counter and the TIM prescaler. Setting TRST has no effect on any
other timer registers. Counting resumes from $0000. TRST is cleared automatically after the counter
is reset and always reads as 0.
1 = Prescaler and counter cleared
0 = No effect
NOTE
Setting the TSTOP and TRST bits simultaneously stops the counter at a
value of $0000.
PS[2:0] — Prescaler Select Bits
These read/write bits select one of the seven prescaler outputs as the input to the counter as
Table 16-1 shows.
Table 16-1. Prescaler Selection
PS2
PS1
PS0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
TIM Clock Source
Internal bus clock ÷ 1
Internal bus clock ÷ 2
Internal bus clock ÷ 4
Internal bus clock ÷ 8
Internal bus clock ÷ 16
Internal bus clock ÷ 32
Internal bus clock ÷ 64
TCLK (if available)
MC68HC908QB8 Data Sheet, Rev. 3
184
Freescale Semiconductor