XR16C2850
SYMBOL DESCRIPTION
Symbol
Pin
44
Signal
type
Pin Description
40
48
pin has no effect on the UARTs transmit or receive opera-
tion.
-RI A-B
39,23 43,26 41,21
32,24 36,27 33,22
I
Ring Indicator (active low) - These inputs are associated
with individual UART channels, A through B. A logic 0 on
this pin indicates the modem has received a ringing signal
from the telephone line. A logic 1 transition on this input pin
will generate an interrupt.
-RTS A-B
O
RequesttoSend(activelow)-Theseoutputsareassociated
withindividualUARTchannels, AthroughB. Alogic0onthe
-RTS pin indicates the transmitter has data ready and
waiting to send. Writing a logic 1 in the modem control
register (MCR bit-1) will set this pin to a logic 0 indicating
data is available. After a reset this pin will be set to a logic
1. This pin has no effect on the UARTs transmit or receive
operation.
RX A-B
TX A-B
-RSCTL
10,9 11,10
5,4
7,8
37
I
O
I
Receive Data (A-B) - These inputs are associated with
individual serial channel data to the 2850 receive input
circuits, A-B. TheRXsignalwillbealogic1duringreset, idle
(no data), or when the transmitter is disabled. During the
local loopback mode, the RX input pin is disabled and TX
data is connected to the UART RX Input, internally.
11,12 13,14
Transmit Data (A-B) - These outputs are associated with
individual serial transmit channel data from the 2850. The
TXsignalwillbealogic1duringreset,idle(nodata),orwhen
the transmitter is disabled. During the local loopback mode,
the TX output pin is disabled and TX data is internally
connected to the UART RX Input.
-
-
RS-485 function select. When this pin is pulled high, normal
-RTS function is selected. RS-485 direction control can be
activated by connecting this pin to GND. This pin is wired
Or-ed with FCTR Bit-3.
Rev. 1.00P
7
EXAR [ EXAR CORPORATION ]
