W83627HF Datasheet, PDF (101/185 Pages) Winbond – WINBOND I/O

W83627HF/F
PRELIMINARY
9. PLUG AND PLAY CONFIGURATION
The W83627HF uses Compatible PNP protocol to access configuration registers for setting up
different types of configurations. In W83627HF, there are eleven Logical Devices (from Logical
Device 0 to Logical Device B with the exception of logical device 4 for backward compatibility) which
correspond to eleven individual functions: FDC (logical device 0), PRT (logical device 1), UART1
(logical device 2), UART2 (logical device 3), KBC (logical device 5), CIR (Consumer IR, logical
device 6), GPIO1 (logical device 7), GPIO2 (logical device 8), GPIO3 (logical device 9), ACPI
((logical device A), and hardware monitor (logical device B). Each Logical Device has its own
configuration registers (above CR30). Host can access those registers by writing an appropriate
logical device number into logical device select register at CR7.
9.1 Compatible PnP
9.1.1 Extended Function Registers
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 out of these two methods of entering the
Extended Function mode as follows:
HEFRAS
0
1
address and value
write 87h to the location 3F0h twice
write 87h to the location 370h twice
After Power-on reset, the value on RTSA (pin 51) 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).
After programming of the configuration register is finished, an additional value (AAh) should be
written to EFERs to exit the Extended Function mode to prevent unintentional access to those
configuration registers. The designer can also set bit 5 of CR26 (LOCKREG) to high to protect the
configuration registers against accidental accesses.
- 84 -
Publication Release Date: Jul 1999
Revision 0.53