
W83977F/ W83977AF
PRELIMINARY
Publication Release Date: March 1998
-10-
Revision 0.58
1.3 Serial Port Interface, continued
SYMBOL
PIN
I/O
FUNCTION
DTRB
ENCPNP
51
I/O
8t
UART B Data Terminal Ready. An active low signal informs the
modem or data set that controller is ready to communicate.
During power-on reset, this pin is pulled down internally and is
defined as ENCPNP, which provides the power-on value for
CR24 bit 1 (ENPNP). A 4.7 k
is recommended if intends to
pull up. (enable comply PnP mode)
SINA
SINB
45,
52
IN
t
Serial Input. Used to receive serial data through the
communication link.
SOUTA
46
I/O
8t
UART A Serial Output. Used to transmit serial data out to the
communication link.
PENKRC
During power-on reset, this pin is pulled down internally and is
defined as PENKRC, which provides the power-on value for
CR24 bit 2 (ENKBRTC). A 4.7 k
is recommended if intends to
pull up. (enable KBC and RTC)
SOUTB
53
I/O
8t
UART B Serial Output. Used to transmit serial data out to the
communication link.
DCDA
DCDB
47
54
65
66
IN
t
Data Carrier Detect. An active low signal indicates the modem
or data set has detected a data carrier.
RIA
RIB
IN
t
Ring Indicator. An active low signal indicates that a ring signal is
being received from the modem or data set.
1.4 Infrared Interface
SYMBOL
IRRX (SINC)
PIN
37
I/O
IN
cs
FUNCTION
Infrared Receiver input. It functions as SIN input if UART C is
configured as a simple serial port.
[W83977AF only]
Infrared Transmitter Output. It functions as SOUT output if
UART C is configured as a simple serial port.
[W83977AF only]
CR2A bit3, 2=00 (default): High speed IR receiving terminal.
CR2A bit3, 2=01: IR module select 0.
CR2A bit3, 2=10: General purpose I/O port 2, bit 5. It can be
configured as GATE A20 (Keyboard P21).
IRTX
(SOUTC)
IRRXH
IRSL0
GP25
(GA20)
38
OUT
12t
CTSC
CIRRX
GP24 (P16)
39
I/O
12t
OUT
12t
I/O
12t
IN
t
IN
t
I/O
12t
CR2A bit3, 2=11: CTS input of UART C.
[W83977AF only]
CR2A bit5, 4=00 (default): Consumer IR receiving terminal.
CR2A bit5, 4=01: General purpose I/O port 2, bit 4. It can be
configured as Keyboard P16 I/O port.
CR2A bit5, 4=10: Keyboard P13 I/O
P13
40
I/O
12t