Rainbow Electronics MAX3107 - Manual (Page 20)

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MAX3107
SPI/I
2
C UART with 128-Word FIFOs
and Internal Oscillator
Echo Suppression
The MAX3107 can suppress echoed data, sometimes
found in half-duplex communication (e.g., RS-485 and
IrDA). If the transceiver’s receiver is not turned off while
the transceiver is transmitting, copies (echoes) are
received by the UART. The MAX3107’s receiver can
block the reception of this echoed data by enabling echo
suppression. Set MODE2[7]: EchoSuprs to 1 to enable
echo suppression.
The MAX3107 receiver can block echoes with a long
round trip delay. The transmitter can be configured
to remain enabled after the end of transmission for a
programmable period of time: the hold time delay. The
hold time delay is set by the HDplxDelay[3:0] register.
See the HDplxDelay description in the Detailed Register
Descriptions section for more information.
Autotransceiver direction control and echo suppression
can operate simultaneously.
Automatic Hardware Flow Control
The MAX3107 is capable of automatic hardware (RTS
and CTS) flow control without the need for host pro-
cessor intervention. When AutoRTS control is enabled,
the MAX3107 automatically controls the RTS hand-
shake without the need for host processor intervention.
AutoCTS flow control separately turns the MAX3107’s
transmitter on and off based on the CTS input. AutoRTS
and AutoCTS flow control are independently enabled
through FlowCtrl[1:0].
AutoRTS Control
AutoRTS flow control ensures that the receive FIFO does
not overflow by signaling to the far-end UART to stop
data transmission. The MAX3107 does this automati-
cally by controlling RTS/CLKOUT. AutoRTS flow control
is enabled through FlowCtrl[0]: AutoRTS. The HALT and
RESUME levels determine the threshold levels at which
RTS/CLKOUT is asserted and deasserted. HALT and
Figure 10. Setup and Hold Times in Autotransceiver Direction Control
Figure 11. Half-Duplex with Echo Suppression
TX
FIRST CHARACTER LAST CHARACTER
RTS/CLKOUT
SETUP
HOLD
MAX3107 MAX13431
TRANSMITTER
TX
B
A
D
RX
TxFIFO
RECEIVER
ECHO
SUPPRESSION
RxFIFO
DI
RO
RE
DE
R
RTS/CLKOUT