User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 491
www.energymicro.com
18 UART - Universal Asynchronous Receiver/
Transmitter
0
1 2 3 4
UART
RX
TX
DMA
controller
RAM
EFM32
Quick Facts
What?
The UART is capable of high-speed
asynchronous serial communication.
Why?
Serial communication is frequently used in
embedded systems and the UART allows
efficient communication with a wide range of
external devices.
How?
The UART has a wide selection of operating
modes, frame formats and baud rates. The
multi-processor mode allows the UART
to remain idle when not addressed. Triple
buffering and DMA support makes high data-
rates possible with minimal CPU intervention
and it is possible to transmit and receive large
frames while the MCU remains in EM1.
18.1 Introduction
The Universal Asynchronous serial Receiver and Transmitter (UART) is a very flexible serial I/O module.
It supports full- and half-duplex asynchronous UART communication.
18.2 Features
• Full duplex and half duplex
• Separate TX / RX enable
• Separate receive / transmit 2-level buffers, with additional separate shift registers
• Programmable baud rate, generated as an fractional division from the peripheral clock (HFPERCLK)
• Max bit-rate
• UART standard mode, peripheral clock rate / 16
• UART FAST mode, peripheral clock rate / 8
• Asynchronous mode supports
• Majority vote baud-reception
• False start-bit detection
• Break generation/detection
• Multi-processor mode
• Configurable number of data bits, 4-16 (plus the parity bit, if enabled)
• HW parity bit generation and check
• Configurable number of stop bits in asynchronous mode: 0.5, 1, 1.5, 2
• HW collision detection
• Multi-processor mode
• Separate interrupt vectors for receive and transmit interrupts
• Loopback mode
• Half duplex communication