xr16m654 Exar Corporation, xr16m654 Datasheet - Page 13

• Manufacturer Part Number: xr16m654
• Description: 1.62v To 3.63v Quad Uart With 64-byte Fifo
• Manufacturer: Exar Corporation

REV. 1.0.0
The RESET input resets the internal registers and the serial interface outputs in both channels to their default
state (see
function in the device. Following a power-on reset or an external reset, the M654 is software compatible with
previous generation of UARTs, 16C454 and 16C554.
The UART provides the user with the capability to bi-directionally transfer information between an external
CPU and an external serial communication device. During Intel Bus Mode (16/68# pin is connected to VCC), a
logic 0 on chip select pins, CSA#, CSB#, CSC# or CSD# allows the user to select UART channel A, B, C or D
to configure, send transmit data and/or unload receive data to/from the UART. Selecting all four UARTs can be
useful during power up initialization to write to the same internal registers, but do not attempt to read from all
four uarts simultaneously. Individual channel select functions are shown in
During Motorola Bus Mode (16/68# pin is connected to GND), the package interface pins are configured for
connection with Motorola, and other popular microprocessor bus types. In this mode the M654 decodes two
additional addresses, A3 and A4, to select one of the four UART ports. The A3 and A4 address decode
function is used only when in the Motorola Bus Mode.
2.2
2.3
Device Reset
Channel Selection
Table
17). An active high pulse of longer than 40 ns duration will be required to activate the reset
CSA# CSB# CSC# CSD#
CS#
1
0
0
0
0
1
0
1
1
1
0
T
T
A4
ABLE
ABLE
X
0
0
1
1
1
1
0
1
1
0
1: C
2: C
A3
X
0
1
0
1
1
1
1
0
1
0
HANNEL
HANNEL
1
1
1
1
0
0
A-D S
A-D S
13
See Table
Channel C selected
Channel D selected
Channel A selected
Channel B selected
1.62V TO 3.63V QUAD UART WITH 64-BYTE FIFO
UART de-selected
ELECT IN
ELECT IN
Channels A-D selected
Channel A selected
Channel B selected
Channel C selected
Channel D selected
F
UART de-selected
UNCTION
F
2.
UNCTION
16 M
68 M
ODE
ODE
Table
1.
XR16M654/654D