XR19L200 Datasheet, PDF (25/40 Pages) Exar Corporation – SINGLE CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER

PRELIMINARY
XR19L200
REV. P1.0.2
SINGLE CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER
MSR[1]: Delta DSR Input Flag
• Logic 0 = No change on DSR input (default).
• Logic 1 = The DSR input has changed state since the last time it was monitored. A modem status interrupt
will be generated if MSR interrupt is enabled (IER bit-3).
MSR[2]: Delta RI Input Flag
• Logic 0 = No change on RI input (default).
• Logic 1 = The RI input has changed from LOW to HIGH, ending of the ringing signal. A modem status
interrupt will be generated if MSR interrupt is enabled (IER bit-3).
MSR[3]: Delta CD Input Flag
• Logic 0 = No change on CD input (default).
• Logic 1 = Indicates that the CD input has changed state since the last time it was monitored. A modem status
interrupt will be generated if MSR interrupt is enabled (IER bit-3).
MSR[4]: CTS Input Status
CTS pin may function as automatic hardware flow control signal input if it is enabled and selected by Auto CTS
(EFR bit-7). Auto CTS flow control allows starting and stopping of local data transmissions based on the
modem CTS signal. A HIGH on the CTS pin will stop UART transmitter as soon as the current character has
finished transmission, and a LOW will resume data transmission. Normally MSR bit-4 bit is the complement of
the CTS input. However in the loopback mode, this bit is equivalent to the RTS bit in the MCR register. The
CTS input may be used as a general purpose input when the modem interface is not used.
MSR[5]: DSR Input Status
Normally this bit is the complement of the DSR input. In the loopback mode, this bit is equivalent to the DTR bit
in the MCR register. The DSR input may be used as a general purpose input when the modem interface is not
used.
MSR[6]: RI Input Status
Normally this bit is the complement of the RI input. In the loopback mode this bit is equivalent to bit-2 in the
MCR register. The RI input may be used as a general purpose input when the modem interface is not used.
MSR[7]: CD Input Status
Normally this bit is the complement of the CD input. In the loopback mode this bit is equivalent to bit-3 in the
MCR register. The CD input may be used as a general purpose input when the modem interface is not used.
4.11 Scratchpad Register (SPR) - Read/Write
This is a 8-bit general purpose register for the user to store temporary data. The content of this register is
preserved during sleep mode but becomes 0xFF (default) after a reset or a power off-on cycle.
4.12 Baud Rate Generator Registers (DLL and DLM) - Read/Write
The concatenation of the contents of DLM and DLL gives the 16-bit divisor value which is used to calculate the
baud rate:
• Baud Rate = (Clock Frequency / 16) / Divisor
See MCR bit-7 and the baud rate table also.
4.13 Device Identification Register (DVID) - Read Only
This register contains the device ID (0x01 for XR19L200). Prior to reading this register, DLL and DLM should
be set to 0x00.
4.14 Device Revision Register (DREV) - Read Only
This register contains the device revision information. For example, 0x01 means revision A. Prior to reading
this register, DLL and DLM should be set to 0x00.
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