W83L518D_05 Datasheet, PDF (13/25 Pages) Winbond – Integrated Media Reader

W83L518D
6.2.3 Extended Function Index Register (EFIR), Extended Function Data Register (EFDR)
After entering Extended Function mode, Extended Function Index Register (EFIR) must be written
with an index value (02h, 07h-FEh) to specify which configuration register is to be accessed through
Extended Function Data Register (EFDR). EFIR is a write-only register at I/O address 2Eh or 4Eh (as
described in section 6.2.1) on a PC/AT system and EFDR is a read/write register at I/O address 2Fh
or 4Fh.
6.3 Configuration Sequence
To program configuration registers, specific configuration sequence must be followed:
(1) Write 83h to EFER twice to enter Extended Function mode.
(2) Select logical device select register by writing 07h to EFIR.
(3) Select logical device by writing a value to EFDR.
(4) Select control/configuration register by writing its index to EFIR.
(5) Access selected control/configuration register through EFDR.
(6) Repeat step 4 ~ 5 as needed.
(7) Leave Extended Function mode by writing AAh to EFER.
Step 2 and step 3 are not necessary for accessing global register (index 00h to 2Fh).
6.3.1 Software programming example
The following example is written in Intel 8086 assembly language. EFER and EFIR are assumed to
be at 2Eh, and EFDR is at 2Fh. Use 4Eh/4Fh instead of 2Eh/2Fh if HEFRAS (bit 6 of CR26) is set.
;-----------------------------------------------------------------------------------
; Enter Extended Function mode, interruptible double-write |
;-----------------------------------------------------------------------------------
MOV DX, 2Eh
MOV AL, 83h
OUT DX, AL
OUT DX, AL
;-----------------------------------------------------------------------------
; Configure logical device 1, configuration register CRF0 |
;-----------------------------------------------------------------------------
MOV DX, 2Eh
MOV AL, 07h
OUT DX, AL
; point to Logical Device Number Reg.
MOV DX, 2Fh
MOV AL, 01h
OUT DX, AL
; select logical device 1
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Publication Release Date: May 11, 2005
Revision 1.0