Datasheet

337
32133D–11/2011
UC3D
20. Universal Synchronous Asynchronous Receiver Transmitter (USART)
Rev: 4.4.0.6
20.1 Features
• Configurable baud rate generator
• 5- to 9-bit full-duplex, synchronous and asynchronous, serial communication
– 1, 1.5, or 2 stop bits in asynchronous mode, and 1 or 2 in synchronous mode
– Parity generation and error detection
– Framing- and overrun error detection
– MSB- or LSB-first
– Optional break generation and detection
– Receiver frequency over-sampling by 8 or 16 times
– Optional RTS-CTS hardware handshaking
– Receiver Time-out and transmitter Timeguard
– Optional Multidrop mode with address generation and detection
• SPI Mode
– Master or slave
– Configurable serial clock phase and polarity
– CLK SPI serial clock frequency up to a quarter of the CLK_USART internal clock frequency
• Test Modes
– Automatic echo, remote- and local loopback
• Supports two Peripheral DMA Controller channels
– Buffer transfers without processor intervention
20.2 Overview
The Universal Synchronous Asynchronous Receiver Transceiver (USART) provides a full
duplex, universal, synchronous/asynchronous serial link. Data frame format is widely configu-
rable, including basic length, parity, and stop bit settings, maximizing standards support. The
receiver implements parity-, framing-, and overrun error detection, and can handle un-fixed
frame lengths with the time-out feature. The USART supports several operating modes, provid-
ing an interface to and SPI buses and infrared transceivers. Communication with slow and
remote devices is eased by the timeguard. Duplex multidrop communication is supported by
address and data differentiation through the parity bit. The hardware handshaking feature
enables an out-of-band flow control, automatically managing RTS and CTS pins. The Peripheral
DMA Controller connection enables memory transactions, and the USART supports chained
buffer management without processor intervention. Automatic echo, remote-, and local loopback
-test modes are also supported.