CONFIGURATION SEQUENCE
Exit Configuration Mode
To program the configuration registers, the
following sequence must be followed:
1. Enter Configuration Mode
To exit the Configuration State the system
writes 0xAA to the CONFIG PORT. The chip
returns to the RUN State.
2. Configure the Configuration Registers
3. Exit Configuration Mode.
Note: Only two states are defined (Run and
Configuration). In the Run State the chip will
always be ready to enter the Configuration
State.
Enter Configuration Mode
To
place
the
chip
into
the
Configuration State the Config Key is sent to
the chip's CONFIG PORT. The config key
consists of 0x55 written to the CONFIG PORT.
Once the configuration key is received
correctly the chip enters into the Configuration
State (The auto Config ports are enabled).
Programming Example
The following is an example of a configuration
program in Intel 8086 assembly language.
;----------------------------.
; ENTER CONFIGURATION MODE
;----------------------------'
MOVDX,3F0H
MOVAX,055H
OUTDX,AL
;----------------------------.
; CONFIGURE REGISTER CRE0,
; LOGICAL DEVICE 8
;----------------------------'
MOVDX,3F0H
MOVAL,07H
OUTDX,AL ; Point to nLD Config Reg
MOVDX,3F1H
MOVAL, 08H
OUTDX,AL; Point to Logical Device
|
Configuration Mode
The system sets the logical device information
and activates desired logical devices through
the INDEX and DATA ports. In configuration
mode, the INDEX PORT is located at the
CONFIG PORT address and the DATA PORT
is at INDEX PORT address + 1.
|
|
The desired configuration registers are
accessed in two steps:
a. Write the index of the Logical Device
Number Configuration Register (i.e., 0x07)
to the INDEX PORT and then write the
number of the desired logical device to the
DATA PORT
b. Write the address of the desired
configuration register within the logical
device to the INDEX PORT and then write
or read the configuration register through
the DATA PORT.
8
;
MOVDX,3F0H
MOVAL,E0H
OUTDX,AL ; Point to CRE0
MOVDX,3F1H
MOVAL,02H
OUTDX,AL ; Update CRE0
;----------------------------.
; EXIT CONFIGURATION MODE
;----------------------------'
MOVDX,3F0H
|
Note: if accessing the Global Configuration
Registers, step (a) is not required.
MOVAX,0AAH
OUTDX,AL
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