w83977tf Winbond Electronics Corp America, w83977tf Datasheet - Page 16

• Manufacturer Part Number: w83977tf
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

1.3 Serial Port Interface
HEFRAS
SINA
SINB
SOUTA
PENKBC
SOUTB
PEN48
DCDA
DCDB
CTSA
CTSB
DSRA
DSRB
RTSA
RTSB
DTRA
PNPCSV
DTRB
SYMBOL
45, 52
PIN
41
48
42
49
43
50
44
51
46
53
47
54
I/O
I/O
I/O
I/O
I/O
I/O
I/O
IN
IN
IN
IN
8t
8t
8t
8t
8t
8t
t
t
t
t
Clear To Send is the modem control input.
The function of these pins can be tested by reading Bit 4 of the
handshake status register.
Data Set Ready. An active low signal indicates the modem or data
set is ready to establish a communication link and transfer data to
the UART.
UART A Request To Send. An active low signal informs the
modem or data set that the controller is ready to send data.
During power-on reset, this pin is pulled down internally and is
defined as HEFRAS, which provides the power-on value for CR26
bit 6 (HEFRAS). A 4.7 k
(select 370H as configuration I/O port s address)
UART B Request To Send. An active low signal informs the
modem or data set that the controller is ready to send data.
UART A Data Terminal Ready. An active low signal informs the
modem or data set that the controller is ready to communicate.
During power-on reset, this pin is pulled down internally and is
defined as PNPCSV , which provides the power-on value for CR24
bit 0 (PNPCSV ). A 4.7 k
(clear the default value of FDC, UARTs, and PRT)
UART B Data Terminal Ready. An active low signal informs the
modem or data set that controller is ready to communicate.
Serial Input. Used to receive serial data through the
communication link.
UART A Serial Output. Used to transmit serial data out to the
communication link.
During power-on reset, this pin is pulled down internally and is
defined as PENKBC, which provides the power-on value for CR24
bit 2 (ENKBC). A 4.7 k resistor is recommended if intends to pull
up. (enable KBC)
UART B Serial Output. During power-on reset, this pin is pulled
down internally and is defined as PEN48, which provides the
power-on value for CR24 bit 6 (EN48). A 4.7 k resistor is
recommended if intends to pull up.
Data Carrier Detect. An active low signal indicates the modem or
data set has detected a data carrier.
-8-
FUNCTION
is recommended if intends to pull up.
is recommended if intends to pull up.
Publication Release Date: April 1998
W83977TF
PRELIMINARY
Revision 0.62