Programmable Interrupt Timer (PIT)
Technical Data MC68HC908AB32 — Rev. 1.0
222 Programmable Interrupt Timer (PIT) MOTOROLA
13.3 Features
Features of the PIT include the following:
• Programmable PIT clock input
• Free-running or modulo up-count operation
• PIT counter stop and reset bits
13.4 Functional Description
Figure 13-1 shows the structure of the PIT. The central component of
the PIT is the 16-bit PIT counter that can operate as a free-running
counter or a modulo up-counter. The counter provides the timing
reference for the interrupt. The PIT counter modulo registers,
PMODH:PMODL, control the modulo value of the counter. Software can
read the counter value at any time without affecting the counting
sequence.
Figure 13-1. PIT Block Diagram
PRESCALER
PRESCALER SELECT
16-BIT COMPARATOR
PPS2 PPS1 PPS0
POF
POIE
PMODH:PMODL
PRST
PSTOP
16-BIT COUNTER
INTERNAL
INTERRUPT
LOGIC
BUS CLOCK
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