Motorola MCF5282, MCF5281 user manual Serial Module Overview

Serial Module Overview

The serial communication channel provides a full-duplex asynchronous/synchronous receiver and transmitter deriving an operating frequency from the system clock or an external clock using the timer pin. The transmitter converts parallel data from the CPU to a serial bit stream, inserting appropriate start, stop, and parity bits. It outputs the resulting stream on the channel transmitter serial data output (UTXDn). See Section 23.5.2.1, “Transmitter.”

The receiver converts serial data from the channel receiver serial data input (URXDn) to parallel format, checks for a start, stop, and parity bits, or break conditions, and transfers the assembled character onto the bus during read operations. The receiver may be polled, interrupt driven, or use DMA requests for servicing. See Section 23.5.2.2, “Receiver.”

23.2 Serial Module Overview

The MCF5282 contains three independent UART modules, whose features are as follows:

•Each can be clocked by the system clock, eliminating a need for an external UART clock

•Full-duplex asynchronous/synchronous receiver/transmitter channel

•Quadruple-buffered receiver

•Double-buffered transmitter

•Independently programmable receiver and transmitter clock sources

•Programmable data format:

—5–8 data bits plus parity

—Odd, even, no parity, or force parity

—One, one-and-a-half, or two stop bits

•Each channel programmable to normal (full-duplex), automatic echo, local loop-back, or remote loop-back mode

•Automatic wake-up mode for multidrop applications

•Four maskable interrupt conditions

•All three UARTs have DMA request capability

•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

23-2 MCF5282 User’s Manual MOTOROLA