w83627thg Winbond Electronics Corp America, w83627thg Datasheet - Page 81

• Manufacturer Part Number: w83627thg
• Description: Winbond Lpc I/o
• Manufacturer: Winbond Electronics Corp America

registers. The designer can also set bit 5 of CR26 (LOCKREG) to high to protect the configuration
registers against accidental accesses.
The configuration registers can be reset to their default or hardware settings only by a cold reset (pin
MR = 1). A warm reset will not affect the configuration registers.
6.1.2
After a power-on reset, the W83627THF enters the default operating mode. Before the W83627THF
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
2Eh or 4Eh (as described in previous section).
6.1.3
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 2Eh or 4Eh (as described
in section 12.2.1) on PC/AT systems, the EFDRs are read/write registers with port address 2Fh or 4Fh
(as described in section 9.2.1) on PC/AT systems.
6.2
To program W83627THF 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
6.2.1
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. 2Eh or 4Eh).
6.2.2
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.
Configuration Sequence
Extended Functions Enable Registers (EFERs)
Extended Function Index Registers (EFIRs), Extended Function Data
Enter the extended function mode
Configuration the configuration registers
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W83627THF/W83627THG