FX3 Programmers Manual, Doc. # 001-64707 Rev. *C 31
FX3 Overview
3.6.3 UART
Figure 3-8. UART Block Diagram
FX3's UART block provides standard asynchronous full-duplex transfer using the TX and RX pins.
Flow control mechanism, RTS (request to send) and CTS (clear to send) pins are supported. The
UART block can operate at numerous baud rates ranging from 300 bps to 4608 Kbps and supports
both one and two stop bits mode of operation. Similar to I2S and I
2
C blocks, this block supports both
single and burst (DMA) data transfers.
The transmitter and receiver components of the UART block can be individually enabled. When both
components are enabled and the UART set in loopback mode, the external interface is disabled;
data scheduled on the TX pin is internally looped back to the RX pin.
Both hardware and software flow control are supported. Flow control settings can individually be set
on the transmitter and receiver components. When both (Tx and Rx) flows are controlled by
hardware, the RTS and CTS signaling is completely managed by the UART block's hardware. When
the flow control is completely handled by software, software can signal a request to send using the
SW_RTS field of the block and monitor the block's CTS_STAT signal.
Transmission starts when a 0-level start bit is transmitted and ends when a 1-level stop bit is
transmitted. This represents the default 10-bit transmission mode. A ninth parity bit can be appended
to data in the 11-bit transmission mode. Both the even and odd parity variants are supported.
Optionally, a fixed check bit (sticky parity) can be inserted in place of the parity bit. The value of this
bit is configurable. Corresponding settings are also available for the Rx block.
The UART Rx line is internally oversampled by a factor of 8 and any three consecutive samples
among the eight can be chosen for the majority vote technique to decide the received bit.
Separate interface devices can be used to convert the logic level signals of the UART to and from
the external voltage signaling standards such as RS-232, RS-422, and RS-485.
DataTerminal
Equipment(DTE)
FX3:DataCarrier
Equipment(DCE)
TX
RX
RX
TX
RTS
RTS
CTS
CTS
DMA/SGL TRANSFER
SGL_TX_DATA
SGL_RX_DATA
DMA_TX_DATA
DMA_RX_DATA
UART_ENABLE
RX_ENABLE
TX_ENABLE
LOOPBACK
RX SAMPLING
INSTANT
SW_RTS
CTS_STAT
HW_TX_FLOW_CTRL_EN
HW_RX_FLOW_CTRL_EN
# STOP BITS
PARITY ODD
PARITY STICKY
TX STICKY BIT
RX STICKY BIT
PARITY
BAUDCLK
To Next Page
Loading...