XR16M2550 Datasheet, PDF (29/47 Pages) Exar Corporation – HIGH PERFORMANCE LOW VOLTAGE DUART WITH 16-BYTE FIFO

REV. 1.0.2
XR16M2550
HIGH PERFORMANCE LOW VOLTAGE DUART WITH 16-BYTE FIFO
LCR BIT-5
X
0
0
1
1
LCR BIT-4
X
0
1
0
1
TABLE 12: PARITY SELECTION
LCR BIT-3
PARITY SELECTION
0
No parity
1
Odd parity
1
Even parity
1
Force parity to mark, HIGH
1
Force parity to space, LOW
LCR[6]: Transmit Break Enable
When enabled, the Break control bit causes a break condition to be transmitted (the TX output is forced to a
“space", LOW 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”, LOW, for alerting the remote receiver of a line
break condition.
LCR[7]: Baud Rate Divisors Enable
Baud rate generator divisor (DLL, DLM and DLD) enable.
• Logic 0 = Data registers are selected (default).
• Logic 1 = Divisor latch registers are selected.
4.7 Modem Control Register (MCR) or General Purpose Outputs Control - Read/Write
The MCR register is used for controlling the serial/modem interface signals or general purpose inputs/outputs.
MCR[0]: DTR# Output
The DTR# pin is a modem control output. If the modem interface is not used, this output may be used as a
general purpose output.
• Logic 0 = Force DTR# output HIGH (default).
• Logic 1 = Force DTR# output LOW.
MCR[1]: RTS# Output
The RTS# pin is a modem control output and may be used for automatic hardware flow control by enabled by
EFR bit-6. If the modem interface is not used, this output may be used as a general purpose output.
• Logic 0 = Force RTS# HIGH (default).
• Logic 1 = Force RTS# LOW.
MCR[2]: IrDA RX Inversion or OP1# (legacy term)
When Infrared mode is enabled (MCR[6]=1 and EFR[4]=1), this bit selects the idle state of the encoded IrDA
data. In internal loopback mode, this bit functions like the OP1# in the 16C550.
• Logic 0 = Select RX input as active-low encoded IrDA data (Idle state will be low) (default).
• Logic 1 = Select RX input as active-high encoded IrDA data (Idle state will be high).
In the Internal Loopback Mode, this bit controls the state of the modem input RI# bit in the MSR register as
shown in Figure 12.
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