W83877TF/W83877TG
Publication Release Date: May 2006
-61- Revision 0.7
8. PLUG AND PLAY CONFIGURATION
A powerful new plug-and-play function has been built into the W83877TF/TG to help simplify the task
of setting up a computer environment. With appropriate support from BIOS manufacturers, the system
designer can freely allocate Winbond I/O devices (i.e., the FDC, PRT and UART ) in the PC's I/O
space (100H - 3FFH). In addition, the W83877TF/TG also provides 8 interrupt requests and 3 DMA
pairs for designers to assign in interfacing FDCs, UARTs, and PRTs. Hence this powerful I/O chip
offers greater flexibility for system designers.
The PnP feature is implemented through a set of Extended Function Registers (CR20 to 29). Details
on configuring these registers are given in Section 11. The default values of these PnP-related
registers set the system to a configuration compatible with environments designed with previous
Winbond I/O chips.
9. ACPI /LEGACY FEATURE AND AUTO POWER MANAGEMENT
9.1 ACPI/Legacy power management
W83877TF/TG supports both ACPI and legacy power management models. For the ACPI power
management, the
SCI pin is dedicated to the SCI interrupt signal for the SCI interrupt handler; For the
legacy power management, the
SMI pin is dedicated to the SMI interrupt signal for the SMI interrupt
handler.
Two register blocks is used for the ACPI/Legacy power management. They are the PM1 and GPE
register blocks. Their base addresses are held in the W83877TF/TG configuration registers CR33 and
CR34 respectively. Configuration registers CR40 to CR45 are for the legacy power management. The
above configuration registers hold the interrupt event enable and status bits of the SMI interrupts.
Control over the routing of SCI and SMI interrupts to the output pins is also contained in the above
registers.
One 24-bit power management timer is also implemented. It provides an accurate time value used by
the system software to measure and profiles system idleness.
9.2 Device(auto) power management
W83877TF/TG also provides the auto power management function for each device within it. They are
the printer port, FDC, UART A, and UART B devices in W83877TF/TG respectively. Device idle and
trap status are provided to indicate the device's working/sleeping state. Device idle timer with
programmable initial value is provided for each device, which enter the powerdown state when the
powerdown conditions are met. Any access to certain registers and external event input will wake up
the devices. The global stand-by timer deals with the other logic part excluding the printer port, FDC,
UART A , and UART B devices. The global stand-by timer reloads and counts down as soon as the 4
devices enter the powerdown mode and W83877TF/TG enters the powerdown mode as soon as it
expires. Once any device is awakened, the global stand-by is also awakened. The initial count values
of the devices are held in the configuration registers CR35 to CR39.
