Semiconductor, Inc.
Ei68C681
Ei88C681
DUAL UART
These ports can be used as general purpose I/O ports
or can be assigned specific functions such as clock
inputs or status/interrupt outputs under program control.
The Ei68C681 are fabricated using Epic’s advanced
CMOS process to provide high performance and low
power consumption.
The DUART provides a flow control capability to inhibit
transmission from a remote device when the buffer of
the receiving DUART is full, thus preventing loss of
data. The DUART also provides a general purpose 16-
bit counter/timer (which may also be used as a
programmable bit rate generator), a multipurpose input
port and a multipurpose output port.
BLOCK DIAGRAM
D0-D7
8
BUS BUFFER
OPERATION
CONTROL
ADDRESS
DECODE
R/W CONTROL
CHANNEL
TRANSMIT
LOGIC
RECEIVE
LOGIC
TxDA
R/W•
DTACK•
CE•
A0-A3
RESET•
4
RxDA
INTR•
IACK•
INTERRUPT
CONTROL
IMR
ISR
IVR
INPUT PORT
6
IPCR
CHANNEL B
(AS ABOVE)
TxDB
RxDB
IP0-IP6
X1/CLK
TIMING
AND
CONTROL
LOGIC
ACR
X2
OUTPUT PORT
OPCR
OPR
8
VCC
GND
14
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