W83627HF/ F/ HG/ G
6.4
Serial Port Interface
SYMBOL
PIN
49
I/O
FUNCTION
CTSA#
CTSB#
INt
Clear To Send. It is the modem control input.
78
The function of these pins can be tested by reading bit 4 of the
handshake status register.
DSRA#
DSRB#
50
79
INt
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.
RTSA#
51
O8C
INcd
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 de-
fined as HEFRAS, which provides the power-on value for CR26 bit 6
（HEFRAS）. A 4.7 k ohm is recommended if intends to pull up.
HEFRAS
（select 4EH as configuration I/O port′s address）
DTRA#
52
O8C
INcd
UART B 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 de-
fined as PNPCVS# , which provides the power-on value for CR24
bit 0, A 4.7k ohm is recommended if intends to pull up.（This bit is
used to clear the default value of FDC, UARTs, and LPT setting）
PNPCVS#
RTSB#
DTRB#
80
81
O8C
O8C
INt
UART B Request To Send. An active low signal informs the modem
or data set that the controller is ready to send data.
UART B Data Terminal Ready. An active low signal informs the
modem or data set that controller is ready to communicate.
SINA
SINB#
53
82
Serial Input. It is used to receive serial data through the communica-
tion link.
SOUTA
54
O8C
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 de-
fined as PENKBC, which provides the power-on value for CR24 bit
2 （PENKBC）. A 4.7 k ohm resistor is recommended if intends to
pull up. （ enable KBC）
INcd
O8C
PENKBC
SOUTB
PEN48
83
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 ohm resistor is recom-
mended if intends to pull up.
INcd
INt
DCDA#
DCDB#
56
84
Data Carrier Detect. An active low signal indicates the modem or
data set has detected a data carrier.
RIA#
RIB#
57
85
INt
Ring Indicator. An active low signal indicates that a ring signal is
being received from the modem or data set.
Publication Release Date: June 09, 2006
- 21 -
Revision 2.27
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