Note: Only two states are defined (Run and
Configuration). In the Run State the chip will
always be ready to enter the Configuration
State.
CONFIGURATION SEQUENCE
To program the configuration registers, the
following sequence must be followed:
1. Enter Configuration Mode
2. Configure the Configuration Registers
3. Exit Configuration Mode.
Programming Example
The following is an example of a configuration
program in Intel 8086 assembly language.
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 two
successive writes of 0x55 data to the CONFIG
PORT. Once the initiation key is received
correctly the chip enters into the Configuration
State (The auto Config ports are enabled).
; ENTER CONFIGURATION MODE
|
;--------------------------------------------------'
MOV
MOV
CLI
OUT
OUT
STI
DX,3F0H
AX,055H
; disable interrupts
DX,AL
DX,AL
Configuration Mode
; enable interrupts
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.
;--------------------------------------------------.
; CONFIGURE REGISTER CRE0,
; LOGICAL DEVICE 8
|
|
;--------------------------------------------------'
MOV
MOV
OUT
MOV
MOV
OUT
;
DX,3F0H
AL,07H
DX,AL ; Point to LD# Config Reg
DX,3F1H
AL, 08H
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.
DX,AL ; Point to Logical Device 8
MOV
MOV
OUT
MOV
MOV
OUT
DX,3F0H
AL,E0H
DX,AL ; Point to CRE0
DX,3F1H
AL,02H
DX,AL ; Update CRE0
;-------------------------------------------------.
; EXIT CONFIGURATION MODE
;-------------------------------------------------'
|
Note: if accessing the Global Configuration
Registers, step (a) is not required.
MOV
MOV
OUT
DX,3F0H
AX,0AAH
DX,AL
Exit Configuration Mode
To exit the Configuration State the system
writes 0xAA to the CONFIG PORT. The chip
returns to the RUN State.
170
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