Motorola MCF5281, MCF5282 user manual DMA Timers DTIM0-DTIM3, General-Purpose Timers GPTA/GPTB

MCF5282 Key Features

•Parity, framing, and overrun error detection

•False-start bit detection

•Line-break detection and generation

•Detection of breaks originating in the middle of a character

•Start/end break interrupt/status

1.1.11 DMA Timers (DTIM0-DTIM3)

There are four independent, DMA-transfer-generating 32-bit timers (DTIM0, DTIM1, DTIM2, DTIM3) on the MCF5282. Each timer module incorporates a 32-bit timer with a separate register set for configuration and control. The timers can be configured to operate from the system clock or from an external clock source using one of the DTINx signals. If the system clock is selected, it can be divided by 16 or 1. The selected clock is further divided by a user-programmable 8-bit prescaler which clocks the actual timer counter register (TCRn). Each of these timers can be configured for input capture or reference compare mode. By configuring the internal registers, each timer may be configured to assert an external signal, generate an interrupt on a particular event, or cause a DMA transfer.

1.1.12 General-Purpose Timers (GPTA/GPTB)

The two general-purpose timers (GPTA and GPTB) are 4-channel timer modules. Each timer consists of a 16-bit programmable counter driven by a 7-stage programmable prescaler. Each of the four channels for each timer can be configured for input capture or output compare. Additionally, one of the channels, channel 3, can be configured as a pulse accumulator.

A timer overflow function allows software to extend the timing capability of the system beyond the 16-bit range of the counter. The input capture and output compare functions allow simultaneous input waveform measurements and output waveform generation. The input capture function can capture the time of a selected transition edge. The output compare function can generate output waveforms and timer software delays. The 16-bit pulse accumulator can operate as a simple event counter or a gated time accumulator.

1.1.13 Periodic Interrupt Timers (PIT0-PIT3)

The four periodic interrupt timers (PIT0, PIT1, PIT2, PIT3) are 16-bit timers that provide precise interrupts at regular intervals with minimal processor intervention. Each timer can either count down from the value written in its PIT modulus register, or it can be a free-running down-counter.

MOTOROLA Chapter 1. Overview 1-13