W83977AF Information Storage Devices, Inc, W83977AF Datasheet - Page 20

• Manufacturer Part Number: W83977AF
• Description: W83877TF Plus Kbc, Cir, RTC
• Manufacturer: Information Storage Devices, Inc

1.2 Advanced Power Management, continued
1.3 Serial Port Interface
HEFRAS
nPENPLL
GP23 (P15)
CTSA
CTSB
DSRA
DSRB
RTSA
PANSW
RTSB
DTRA
PNPCSV
DCDC
SYMBOL
SYMBOL
PIN
PIN
73
41
48
42
49
43
50
44
I/O
I/O
I/O
I/O
I/O
I/O
IN
IN
IN
IN
12t
8t
8t
8t
t
t
t
t
CR2B bit7, 6=00 (default): On/Off switch for Advanced Power
Management (APM). This signal indicates a request to switch
the power on or off. When the V
high to low transition on this pin indicates a switch on request.
When V
switch off request.
CR2B bit7, 6=01: General purpose I/O port 2, bit 3. It can be
configured as Keyboard P15 I/O port.
CR2B bit7, 6=11: DCD input of UART C. [W83977AF only]
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
pull up. (select 370H as configuration I/O port address)
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
defined as n PENPLL , which provides the power-on value for
CR24 bit 5 (ENPLL) and bit 6. A 4.7 k
intends to pull up. (PLL is disabled)
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
pull up. (clear the default value of FDC, UARTs, and PTR)
DD
returns, a high to low transition on this pin indicates a
W83977F/ W83977AF
FUNCTION
FUNCTION
Publication Release Date: March 1998
DD
is recommended if intends to
is recommended if intends to
of the chip is disrupted, a
PRELIMINARY
-9 -
is recommended if
Revision 0.58