MC68HC908AT32 Datasheet, PDF (185/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 18
Timer Interface (TIMA-4)
NOTE
This timer is for the MC68HC08AZ32 emulator protocol only.
18.1 Introduction
This section describes the timer interface module (TIMA-4). The TIMA is a 4-channel timer that provides
a timing reference with input capture, output compare, and pulse-width modulation functions. Figure 18-1
is a block diagram of the TIMA.
18.2 Features
Features of the TIMA-4 include:
• Four input capture/output compare channels
– Rising-edge, falling-edge, or any-edge input capture trigger
– Set, clear, or toggle output compare action
• Buffered and unbuffered pulse width-modulation (PWM) signal generation
• Programmable TIMA clock input:
– 7-frequency internal bus clock prescaler selection
– External TIMA clock input (4-MHz maximum frequency)
• Free-running or modulo up-counter operation
• Toggle any channel pin on overflow
• TIMA counter stop and reset bits
18.3 Functional Description
Figure 18-1 shows the TIMA structure. The central component of the TIMA is the 16-bit TIMA counter that
can operate as a free-running counter or a modulo up-counter. The TIMA counter provides the timing
reference for the input capture and output compare functions. The TIMA counter modulo registers,
TAMODH–TAMODL, control the modulo value of the TIMA counter. Software can read the TIMA counter
value at any time without affecting the counting sequence.
The four TIMA channels are programmable independently as input capture or output compare channels.
MC68HC908AT32 Data Sheet, Rev. 3.1
Freescale Semiconductor
185