xr16c2450ip Exar Corporation, xr16c2450ip Datasheet - Page 11

• Manufacturer Part Number: xr16c2450ip
• Description: Dual Uart With Higher Operating Speed And Lower Access Time
• Manufacturer: Exar Corporation

xr
REV. 1.0.0
The 2450 UART provides an internal loopback capability for system diagnostic purposes. The internal
loopback mode is enabled by setting MCR register bit-4 to logic 1. All regular UART functions operate normally.
Figure 7
output is internally routed to the receive shift register input allowing the system to receive the same data that it
was sending. The TX pin is held at logic 1 or mark condition while RTS# and DTR# are de-asserted, and
CTS#, DSR# CD# and RI# inputs are ignored. Caution: the RX input must be held to a logic 1 during loopback
test else upon exiting the loopback test the UART may detect and report a false “break” signal.
2.10
Internal Loopback
shows how the modem port signals are re-configured. Transmit data from the transmit shift register
F
IGURE
7. I
NTERNAL
Transmit Shift Register
Receive Shift Register
L
OOP
(RHR/FIFO)
(THR/FIFO)
B
ACK IN
C
RTS#
CTS#
DTR#
DSR#
HANNELS
OP2#
CD#
RI#
MCR bit-4=1
11
VCC
VCC
OP1#
VCC
A
VCC
AND
B
TXA/TXB
RXA/RXB
RTSA#/RTSB#
CTSA#/CTSB
DTRA#/DTRB#
DSRA#/DSRB#
RIA#/RIB#
CDA#/CDB#
OP2A#/OP2B#
2.97V TO 5.5V DUART
XR16C2450