MC68HC908AT32 Datasheet, PDF (222/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

Modulo Timer (TIM)
Address: $004B
Bit 7
6
5
4
3
Read: TOF
0
0
TOIE TSTOP
Write: 0
TRST
2
1
Bit 0
PS2
PS1
PS0
Reset: 0
0
1
0
0
0
0
0
= Unimplemented
Figure 20-3. TIM Status and Control Register (TSC)
TOF — TIM Overflow Flag
This read/write flag is set when the TIM counter resets to $0000 after reaching the modulo value
programmed in the TIM counter modulo registers. Clear TOF by reading the TIM status and control
register when TOF is set and then writing a logic 0 to TOF. If another TIM overflow occurs before the
clearing sequence is complete, then writing logic 0 to TOF has no effect. Therefore, a TOF interrupt
request cannot be lost due to inadvertent clearing of TOF. Reset clears the TOF bit. Writing a logic 1
to TOF has no effect.
1 = TIM counter has reached modulo value.
0 = TIM 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. Reset clears the
TOIE bit.
1 = TIM overflow interrupts enabled
0 = TIM overflow interrupts disabled
TSTOP — TIM Stop Bit
This read/write bit stops the TIM counter. Counting resumes when TSTOP is cleared. Reset sets the
TSTOP bit, stopping the TIM counter until software clears the TSTOP bit.
1 = TIM counter stopped
0 = TIM counter active
NOTE
Do not set the TSTOP bit before entering wait mode if the TIM is required
to exit wait mode.
TRST — TIM Reset Bit
Setting this write-only bit resets the TIM counter and the TIM prescaler. Setting TRST has no effect on
any other registers. Counting resumes from $0000. TRST is cleared automatically after the TIM
counter is reset and always reads as logic 0. Reset clears the TRST bit.
1 = Prescaler and TIM counter cleared
0 = No effect
NOTE
Setting the TSTOP and TRST bits simultaneously stops the TIM 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 TIM counter as Table
20-1 shows. Reset clears the PS[2:0] bits.
MC68HC908AT32 Data Sheet, Rev. 3.1
222
Freescale Semiconductor