w83977atf Winbond Electronics Corp America, w83977atf Datasheet - Page 166

• Manufacturer Part Number: w83977atf
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

W83977ATF
PRELIMINARY
W83977ATF
uses Compatible PNP protocol to access configuration registers for setting up different
W83977ATF, there are nine Logical Devices (
Logical Device A,
which correspond to ten
individual functions:
(logical device 3), KBC (logical device 5), IR (logical device 6), GPIO1 (logical device 7), GPIO2
(logical device 8), GPIO3 (logical device 9), and ACPI ((logical device A).
its own configuration registers (above CR30).
Host can access those registers
by writing an
.
8.1 Compatible PnP
In Compatible PnP, there are two ways to enter Extended Function and read or write the configuration
registers. HEFRAS (CR26 bit 6) can be used to select one of these two methods of entering the
HEFRAS
address and value
write 87h to the location 3F0h twice
1
After Power-on reset, the value on RTSA (pin 43) is latched by HEFRAS of CR26. In Compatible
PnP, a specific value (87h) must be written twice to the Extended Functions Enable Register (I/O port
address 3F0h or 370h). Secondly, an index value (02h, 07h-FFh) must be written to the Extended
Functions Index Register (I/O port address 3F0h or 370h same as Extended Functions Enable
Register) to identify which configuration register is to be accessed. The designer can then access the
desired configuration register through the Extended Functions Data Register (I/O port address 3F1h
or 371h).
Publication Release Date:April 1998
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Revision 0.53