XR16C850CM-F Datasheet, PDF (34/56 Pages) Exar Corporation – 2.97V TO 5.5V UART WITH 128-BYTE FIFO

XR16C850
2.97V TO 5.5V UART WITH 128-BYTE FIFO
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REV. 2.3.1
LCR[7]: Baud Rate Divisors Enable
Baud rate generator divisor (DLL/DLM) 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 to a logic 1 (default).
• Logic 1 = Force DTR# output to a logic 0.
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# output to a logic 1 (default).
• Logic 1 = Force RTS# output to a logic 0.
MCR[2]: OP1# Output/Auto RS485 Control
OP1# is a general purpose output. If Auto RS-485 mode is enabled, this works as the half-duplex direction
control output. See FCTR[3] for more details.
• Logic 0 = OP1# output is at logic 1.
• Logic 1 = OP1# output is at logic 0.
MCR[3]: OP2# or IRQn Enable during PC Mode
OP2# is a general purpose output available during the Intel bus interface mode of operation. In the PC bus
mode, this bit enables the IRQn operation. See PC Mode section and IRQn pin description. The OP2# output
is not available in the PC Mode.
During Intel Bus Mode Operation:
• Logic 0 = Sets OP2# output to a logic 1 (default).
• Logic 1 = Sets OP2# output to a logic 0.
During PC Mode Operation:
See Table 3 for more details.
MCR[4]: Internal Loopback Enable
• Logic 0 = Disable loopback mode (default).
• Logic 1 = Enable local loopback mode, see loopback section and Figure 16.
MCR[5]: Xon-Any Enable
• Logic 0 = Disable Xon-Any function (for 16C550 compatibility, default).
• Logic 1 = Enable Xon-Any function. In this mode, any RX character received will resume transmit operation.
The RX character will be loaded into the RX FIFO , unless the RX character is an Xon or Xoff character and
the 850 is programmed to use the Xon/Xoff flow control.
MCR[6]: Infrared Encoder/Decoder Enable
• Logic 0 = Enable the standard modem receive and transmit input/output interface (default).
• Logic 1 = Enable infrared IrDA receive and transmit inputs/outputs. The TX/RX output/input are routed to the
infrared encoder/decoder. The data input and output levels conform to the IrDA infrared interface
requirement. While in this mode, the infrared TX output will be a logic 0 during idle data conditions.
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