User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 494
www.energymicro.com
• Supports baud rates from 300 baud/s to 9600 baud/s
• Can use a high frequency clock source for even higher baud rates
• Configurable number of data bits: 8 or 9 (plus parity bit, if enabled)
• Configurable parity: off, even or odd
• HW parity bit generation and check
• Configurable number of stop bits, 1 or 2
• Capable of sleep-mode wakeup on received frame
• Either wake-up on any received byte or
• Wake up only on specified start and signal frames
• Supports transmission and reception in EM0, EM1 and EM2 with
• Full DMA support
• Specified start-byte can start reception automatically
• IrDA modulator (pulse generator, pulse extender)
• Multi-processor mode
• Loopback mode
• Half duplex communication
• Communication debugging
• PRS RX input
19.3 Functional Description
An overview of the LEUART module is shown in Figure 19.1 (p. 494) .
Figure 19.1. LEUART Overview
TX Buffer
TX Shift Register
Signal fram e interrupt
RX Buffer
RX Shift Register
LEUn_RX
UART Control
and status
Peripheral Bus
TX Baud rate
generator
RX Baud rate
generator
Start fram e
(STARTFRAME)
RX Wakeup
SYNC
=
Pulse
extend
Pulse
gen
Signal fram e
(SIGFRAME)
=
Start fram e interrupt
!RXBLOCK
LEUn_TX
PRS Input
19.3.1 Frame Format
The frame format used by the LEUART consists of a set of data bits in addition to bits for synchronization
and optionally a parity bit for error checking. A frame starts with one start-bit (S), where the line is driven