W83977ATF Datasheet, PDF (11/207 Pages) Winbond – WINBOND I/O

1.3 Serial Port Interface
SYMBOL PIN
I/O
CTSA
CTSB
41
IN_t
48
DSRA
DSRB
RTSA
42
IN_t
49
43
I/O_8t
HEFRAS
RTSB
50
I/O_8t
DTRA
44
I/O_8t
PNPCSV
DTRB
51
I/O_8t
SINA
SINB
SOUTA
45, 52
46
IN_t
I/O_8t
PENKBC
SOUTB
PEN48
DCDA
DCDB
RIA
RIB
53
I/O_8t
47
IN_t
54
65
IN_t
66
W83977ATF
PRELIMINARY
FUNCTION
Clear To Send. This 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 kΩ is recommended if intends to
pull up. (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 kΩ is recommended if intends to
pull up. (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. It is used to receive serial data through the
communication link.
UART A Serial Output. It is 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 kΩ 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 kΩ 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.
Ring Indicator. An active low signal indicates that a ring signal is
being received from the modem or data set.
Publication Release Date: April 1998
-10-
Revision 0.52