MC68HC908AT32 Datasheet, PDF (219/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 20
Modulo Timer (TIM)
20.1 Introduction
This section describes the modulo timer which is a periodic interrupt timer whose counter is clocked
internally via software programmable options. Figure 20-1 is a block diagram of the TIM.
20.2 Features
Features of the TIM include:
• Programmable TIM clock input
• Free-running or modulo up-counter operation
• TIM counter stop and reset bits
20.3 Functional Description
Figure 20-1 shows the structure of the TIM. The central component of the TIM is the 16-bit TIM counter
that can operate as a free-running counter or a modulo up-counter. The counter provides the timing
reference for the interrupt. The TIM counter modulo registers, TMODH–TMODL, control the modulo value
of the counter. Software can read the counter value at any time without affecting the counting sequence.
INTERNAL
BUS CLOCK
PRESCALER
CSTOP
CRST
16-BIT COUNTER
PRESCALER SELECT
PS2
PS1
PS0
16-BIT COMPARATOR
PITTMODH:PITTMODL
Figure 20-1. TIM Block Diagram
TOF
INTER-
RUPT
TOIE
LOGIC
MC68HC908AT32 Data Sheet, Rev. 3.1
Freescale Semiconductor
219