xr16l784iv Exar Corporation, xr16l784iv Datasheet - Page 18

• Manufacturer Part Number: xr16l784iv
• Description: High Performance 2.97v To 5.5v Quad Uart
• Manufacturer: Exar Corporation

XR16L784
HIGH PERFORMANCE 2.97V TO 5.5V QUAD UART
Each UART channel 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 12
output is internally routed to the receive shift register input allowing the system to receive the same data that it
was sending. The TX, RTS# and DTR# pins are held HIGH (idle or de-asserted state), and the CTS#, DSR#
CD# and RI# inputs are ignored.
2.16
Internal Loopback
shows how the modem port signals are re-configured. Transmit data from the transmit shift register
F
IGURE
12. I
NTERNAL
Transmit Shift Register
Receive Shift Register
L
OOP
(RHR/FIFO)
(THR/FIFO)
B
ACK
RTS#
CTS#
DTR#
DSR#
CD#
RI#
MCR bit-4=1
18
VCC
VCC
OP1#
OP2#
VCC
TX [3:0]
RX [3:0]
RTS# [3:0]
CTS# [3:0]
DTR# [3:0]
DSR# [3:0]
RI# [3:0]
CD# [3:0]
xr
REV. 1.2.2