XR17D158 Exar Corporation, XR17D158 Datasheet - Page 44

• Manufacturer Part Number: XR17D158
• Description: Eight-channel Pci-bus Uart
• Manufacturer: Exar Corporation

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PRELIMINARY
LCR[6]: Transmit Break Enable
LCR[7]: Baud Rate Divisors Enable
Baud rate generator divisor (DLL/DLM) enable.
MODEM CONTROL REGISTER (MCR)
The MCR register is used for controlling the modem interface signals or general purpose inputs/outputs.
MCR[0]: DTR# Pins
The DTR# pin may be used for automatic hardware flow control enabled by EFR bit-6 and MCR bit-2=1. If the
modem interface is not used, this output may be used for general purpose.
MCR[1]: RTS# Pins
The RTS# pin may be used for automatic hardware flow control by enabled by EFR bit-6 and MCR bit-2=0. If
the modem interface is not used, this output may be used for general purpose.
MCR[2]: DTR# or RTS# for Auto Flow Control
DTR# or RTS# auto hardware flow control select. This bit is in effect only when auto RTS/DTR is enabled by
EFR bit-6. DTR# selection is associated with DSR# and RTS# is with CTS#.
MCR[3]:
Reserved. Logic zero is default.
MCR[4]: Internal Loopback Enable
MCR[5]: Xon-Any Enable
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When enabled the Break control bit it causes a break condition to be transmitted (the TX output is forced to a
“space’, logic 0, state). This condition remains until disabled by setting LCR bit-6 to a logic 0.
Logic 0 = No TX break condition (default).
Logic 1 = Forces the transmitter output (TX) to a “space”, logic 0, for alerting the remote receiver of a line
break condition.
Logic 0 = Data registers are selected (default).
Logic 1 = Divisor latch registers are selected.
Logic 0 = Force DTR# output to a logic 1 (default).
Logic 1 = Force DTR# output to a logic 0.
Logic 0 = Force RTS# output to a logic 1 (default).
Logic 1 = Force RTS# output to a logic 0.
Logic 0 = Uses RTS# and CTS# pins for auto hardware flow control.
Logic 1 = Uses DTR# and DSR# pins for auto hardware flow control.
Logic 0 = Disable loopback mode (default).
Logic 1 = Enable local loopback mode, see loopback section and
Logic 0 = Disable Xon-Any function (for 16C550 compatibility) (default).
Logic 1 = Enable Xon-Any function. In this mode any RX character received will enable Xon, resume data
transmission.
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UNIVERSAL (3.3V AND 5V) PCI BUS OCTAL UART
Figure
13.
XR17D158
REV. P1.0.0