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MC68HC08AZ32A Datasheet, PDF (151/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit
I/O Registers
POF — PIT Overflow Flag Bit
This read/write flag is set when the PIT counter reaches the modulo value programmed in the PIT
counter modulo registers. Clear POF by reading the PIT status and control register when POF is set
and then writing a 0 to POF. If another PIT overflow occurs before the clearing sequence is complete,
then writing 0 to POF has no effect. Therefore, a POF interrupt request cannot be lost due to
inadvertent clearing of POF. Reset clears the POF bit. Writing a 1 to POF has no effect.
1 = PIT counter has reached modulo value
0 = PIT counter has not reached modulo value
POIE — PIT Overflow Interrupt Enable Bit
This read/write bit enables PIT overflow interrupts when the POF bit becomes set. Reset clears the
POIE bit.
1 = PIT overflow interrupts enabled
0 = PIT overflow interrupts disabled
PSTOP — PIT Stop Bit
This read/write bit stops the PIT counter. Counting resumes when PSTOP is cleared. Reset sets the
PSTOP bit, stopping the PIT counter until software clears the PSTOP bit.
1 = PIT counter stopped
0 = PIT counter active
NOTE
Do not set the PSTOP bit before entering wait mode if the PIT is required
to exit wait mode.
PRST — PIT Reset Bit
Setting this write-only bit resets the PIT counter and the PIT prescaler. Setting PRST has no effect on
any other registers. Counting resumes from $0000. PRST is cleared automatically after the PIT
counter is reset and always reads as logic zero. Reset clears the PRST bit.
1 = Prescaler and PIT counter cleared
0 = No effect
NOTE
Setting the PSTOP and PRST bits simultaneously stops the PIT counter at
a value of $0000.
PPS[2:0] — Prescaler Select Bits
These read/write bits select one of the seven prescaler outputs as the input to the PIT counter as Table
12-1 shows. Reset clears the PPS[2:0] bits.
Table 12-1. Prescaler Selection
PPS[2:0]
000
001
010
011
100
101
110
111
PIT 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
Internal bus clock ÷ 64
MC68HC08AZ32A Data Sheet, Rev. 2
Freescale Semiconductor
151