w83977atg Winbond Electronics Corp America, w83977atg Datasheet - Page 118

• Manufacturer Part Number: w83977atg
• Description: W83877tf Plus Kbc, Gp I/o, Wake-up, Fir, Cir, Pb-free
• Manufacturer: Winbond Electronics Corp America

W83977ATF/W83977ATG
11.1.2 Extended Functions Enable Registers (EFERs)
After
a
power-on
reset,
W83977ATF/ATG
enters
the
default
operating
mode.
Before
W83977ATF/ATG enters the extended function mode, a specific value must be programmed into the
Extended Function Enable Register (EFER) so that the extended function register can be accessed.
The Extended Function Enable Registers are write-only registers. On a PC/AT system, their port
addresses are 3F0h or 370h (as described in previous section).
11.1.3 Extended Function Index Registers (EFIRs), Extended Function Data Registers
(EFDRs)
After the extended function mode is entered, the Extended Function Index Register (EFIR) must be
loaded with an index value (02h, 07h-FEh) to access Configuration Register 0 (CR0), Configuration
Register 7 (CR07) to Configuration Register FE (CRFE), and so forth through the Extended Function
Data Register (EFDR). The EFIRs are write-only registers with port address 3F0h or 370h on PC/AT
systems; the EFDRs are read/write registers with port address 3F1h or 371h on PC/AT systems.
11.2 Configuration Sequence
To program W83977ATF/ATG configuration registers, the following configuration sequence must be
followed:
(1). Enter the extended function mode
(2). Configure the configuration registers
(3). Exit the extended function mode
Enter the extended function mode
To place the chip into the extended function mode, two successive writes of 0x87 must be applied to
Extended Function Enable Registers (EFERs, i.e. 3F0h or 370h).
Configurate the configuration registers
The chip selects the logical device and activates the desired logical devices through Extended
Function Index Register (EFIR) and Extended Function Data Register (EFDR). EFIR is located at the
same address as EFER, and EFDR is located at address (EFIR+1).
First, write the Logical Device Number (i.e., 0x07) to the EFIR and then write the number of the
desired logical device to the EFDR. If accessing the Chip (Global) Control Registers, this step is not
required.
Secondly, write the address of the desired configuration register within the logical device to the EFIR
and then write (or read) the desired configuration register through EFDR.
Exit the extended function mode
To exit the extended function mode, one write of 0xAA to EFER is required. Once the chip exits the
extended function mode, it is in the normal running mode and is ready to enter the configuration
mode.
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