Datasheet

MC9S12XDP512 Data Sheet, Rev. 2.21
Freescale Semiconductor 541
Chapter 13
Periodic Interrupt Timer (S12PIT24B4CV1)
13.1 Introduction
The period interrupt timer (PIT) is an array of 24-bit timers that can be used to trigger peripheral modules
or raise periodic interrupts. Refer to Figure 13-1 for a simplified block diagram.
13.1.1 Glossary
13.1.2 Features
The PIT includes these features:
• Four timers implemented as modulus down-counters with independent time-out periods.
• Time-out periods selectable between 1 and 2
24
bus clock cycles. Time-out equals m*n bus clock
cycles with 1 <= m <= 256 and 1 <= n <= 65536.
• Timers that can be enabled individually.
• Four time-out interrupts.
• Four time-out trigger output signals available to trigger peripheral modules.
• Start of timer channels can be aligned to each other.
13.1.3 Modes of Operation
Refer to the SoC guide for a detailed explanation of the chip modes.
• Run mode
This is the basic mode of operation.
• Wait mode
Acronyms and Abbreviations
PIT
Periodic Interrupt Timer
ISR
Interrupt Service Routine
CCR
Condition Code Register
SoC
System on Chip
micro time bases
clock periods of the 16-bit timer modulus down-counters, which are generated by the 8-bit
modulus down-counters.