xr16v794iv Exar Corporation, xr16v794iv Datasheet - Page 3

• Manufacturer Part Number: xr16v794iv
• Description: High Performance 2.25v To 3.6v Quad Uart With Fractional
• Manufacturer: Exar Corporation

REV. 1.0.0
PIN DESCRIPTIONS
DATA BUS INTERFACE
MODEM OR SERIAL I/O INTERFACE
(R/W#)
RTS0#
CTS0#
A7-A0
D7:D0
N
IOW#
IOR#
INT#
CS#
RX0
TX0
AME
6-1,64,63
18-11
P
62
61
53
60
55
59
IN
7
8
HIGH PERFORMANCE 2.25V TO 3.6V QUAD UART WITH FRACTIONAL BAUD RATE
#
T
OD
YPE
IO
O
O
I
I
I
I
I
I
Address data lines [7:0]. A0:A3 selects individual UART’s 16 configuration regis-
ters, A4:A6 selects UART channel 0 to 3, and A7 selects the global device configu-
ration registers
Data bus lines [7:0] (bidirectional).
When 16/68# pin is HIGH, it selects Intel bus interface and this input is read strobe
(active low). The falling edge instigates an internal read cycle and retrieves the
data byte from an internal register pointed by the address lines [A7:A0], puts it on
the data bus to allow the host processor to read it on the leading edge.
When 16/68# pin is LOW, it selects Motorola bus interface and this input should be
connected to VCC.
When 16/68# pin is HIGH, it selects Intel bus interface and this input becomes write
strobe (active low). The falling edge instigates the internal write cycle and the lead-
ing edge transfers the data byte on the data bus to an internal register pointed by
the address lines.
When 16/68# pin is LOW, it selects Motorola bus interface and this input becomes
read (logic 1) and write (logic 0) signal.
When 16/68# pin is HIGH, this input is chip select (active low) to enable the
XR16V794 device.
When 16/68# pin is LOW, this input becomes the read and write strobe (active low)
for the Motorola bus interface.
Global interrupt output from XR16V794 (open drain, active low). This output
requires an external pull-up resistor (47K-100K ohms) to operate properly. It may
be shared with other devices in the system to form a single interrupt line to the host
processor and have the software driver polls each device for the interrupt status.
UART channel 0 Transmit Data or infrared transmit data. Normal TXD output idles
HIGH while infrared TXD output idles LOW.
UART channel 0 Receive Data or infrared receive data. Normal RXD input idles
HIGH while infrared RXD input idles LOW. In the infrared mode, the polarity of the
incoming RXD signal can be selected via FCTR bit-4. If this bit is a logic 0, a LOW
on the RXD input is considered a mark and if this bit is a logic 1, a HIGH on the
RXD input is considered a space.
UART channel 0 Request to Send or general purpose output (active low). This port
must be asserted prior using for one of two functions:
1) auto RTS flow control, see EFR bit-6, MCR bits-1 & 2, FCTR bits 0-3 and IER
2) Auto RS485 half-duplex direction control, see FCTR bit-5, MCR bit-2 and MSR
UART channel 0 Clear to Send or general purpose input (active low). It can be used
for auto CTS flow control, see EFR bit-7, MCR bit-2 and IER bit-7.
bit-6
bits 4-7.
3
D
ESCRIPTION
XR16V794