CONFIGURATION REGISTER PROGRAMMING
The FDC37N3869 contains configuration registers CR00-CR2F. After the FDC37N3869 enters the configuration
state, configuration registers can be programmed by first writing the register index number (00 - 2FH) to the
Configuration Select Register (CSR) through the INDEX PORT and then writing or reading the configuration register
contents through the DATA PORT. Configuration register access remains enabled until the configuration state is
explicitly exited.
EXITING THE CONFIGURATION STATE
To exit the configuration state, write one byte of AAH data to the CONFIG PORT. The FDC37N3869 will
automatically deactivate the Configuration Access Ports following this procedure, at which point configuration register
access cannot occur until the configuration state is explicitly re-enabled.
PROGRAMMING EXAMPLE
The following is a configuration register programming example written in Intel 8086 assembly language.
;-----------------------------.
; ENTER CONFIGURATION STATE |
;-----------------------------‘
MOV
MOV
OUT
DX,3F0H
AX,055H
DX,AL
;SYSOPT = 0
;-----------------------------.
; CONFIGURE REGISTERS CR0-CRx |
;-----------------------------‘
MOV
MOV
OUT
MOV
MOV
OUT
;
DX,3F0H
AL,00H
DX,AL
;Point to CR0
;Update CR0
DX,3F1H
AL,3FH
DX,AL
MOV
MOV
OUT
MOV
MOV
OUT
;
DX,3F0H
AL,01H
DX,AL
;Point to CR1
;Update CR1
DX,3F1H
AL,9FH
DX,AL
; Repeat for all CRx registers
;
;-----------------------------.
; EXIT CONFIGURATION STATE
;-----------------------------‘
|
MOV
MOV
OUT
DX,3F0H
AX,AAH
DX,AL
CONFIGURATION SELECT REGISTER (CSR)
The Configuration Select Register can only be accessed when the FDC37N3869 is in the configuration state. The
CSR is located at the INDEX PORT address and must be initialized with configuration register index before the
register can be accessed using the DATA PORT.
SMSC DS – FDC37N3869
Page 97
Rev. 10/25/2000
SMSC [ SMSC CORPORATION ]
