W83977EF Winbond Electronics Corp America, W83977EF Datasheet - Page 15

• Manufacturer Part Number: W83977EF
• Description: Description = W83877TF Plus Kbc, GP I/O, Wake-Up, Power Fail Resume ;; Package = QFP 128
• Manufacturer: Winbond Electronics Corp America

1.2 General Purpose I/O Port ,continued
1.3 Serial Port Interface
PANSWIN#
GP23
(P15)
SUSC#
(GA20)
GP25
CTSA#
CTSB#
DSRA#
DSRB#
RTSA#
HEFRAS
RTSB#
SYMBOL
SYMBOL
PIN
41
48
42
49
43
50
PIN
73
39
I/O
I/O
I/O
I/O
IN
I/O
IN
IN
I/O
IN
12t
ts
8t
8t
12
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 Ω 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.
Panel Switch input. (CR2B bit 7_6 = 00, default)
General purpose I/O port 2 bit 3. (CR2B bit 7_6 = 01)
Alternate Function from GP23: KBC P15 I/O port
Suspend C input
Alternate Function from GP25: GATE A20 (KBC P21)
General purpose I/O port 2 bit 5.
-9 -
FUNCTION
FUNCTION
Publication Release Date: April 2003
W83977EF
Revision 1.1