Chapter 20

General Purpose Timer Modules

(GPTA and GPTB)

The MCF5282 has two 4-channel general purpose timer modules (GPTA and GPTB). Each consists of a 16-bit counter driven by a 7-stage programmable prescaler.

A timer overflow function allows software to extend the timing capability of the system beyond the 16-bit range of the counter. Each of the four timer channels can be configured for input capture, which can capture the time of a selected transition edge, or for output compare, which can generate output waveforms and timer software delays. These functions allow simultaneous input waveform measurements and output waveform generation.

Additionally, one of the channels, channel 3, can be configured as a 16-bit pulse accumulator that can operate as a simple event counter or as a gated time accumulator. The pulse accumulator uses the GPT channel 3 input/output pin in either event mode or gated time accumulation mode.

20.1 Features

Features of the general-purpose timer include:

Four 16-bit input capture/output compare channels

16-bit architecture

Programmable prescaler

Pulse widths variable from microseconds to seconds

Single 16-bit pulse accumulator

Toggle-on-overflow feature for pulse-width modulator (PWM) generation

External timer clock input (SYNCA/SYNCB)

MOTOROLA

Chapter 20. General Purpose Timer Modules (GPTA and GPTB)

20-1

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Motorola MCF5281, MCF5282 user manual Chapter General Purpose Timer Modules Gpta and Gptb