MEC1322 datasheet(83/456 Pages) MICROCHIP

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DS00001719D-page 83

MEC1322

5.8.3

CONFIGURATION PORT

The LPC Host can access the Chip’s Configuration Registers through the Configuration Port when CONFIG MODE is

enabled. The device defaults to CONFIG MODE being disabled.

The Configuration Port is composed of an INDEX and DATA Register. The INDEX register is used as an address pointer

to an 8-bit configuration register and the DATA register is used to read or write the data value from the indexed config-

uration register. Once CONFIG MODE is enabled, reading the Configuration Port Data register will return the data value

that is in the indexed Configuration Register.

If no value was written to the INDEX register, reading the Data Register in the Configuration Port will return the value in

Configuration Address location 00h (default).

Note 5-7

The default Base I/O Address of the Configuration Port can be relocated by programming the BAR

the general case for determining the I/O address for each register.

5.8.3.1

Enable CONFIG MODE

The INDEX and DATA registers are effective only when the chip is in CONFIG MODE. CONFIG MODE is enabled when

the Config Entry Key is successfully written to the I/O address of the INDEX register of the CONFIG PORT while the

CONFIG MODE is disabled (see Section 5.8.3.2, "Disable CONFIG MODE").

Config Entry Key = < 55h>

5.8.3.2

Disable CONFIG MODE

CONFIG MODE defaults to disabled on a VCC1_RESET, nSIO_RESET, and when LRESET# is asserted. CONFIG

MODE is also disabled when the following Config Exit Key is successfully written to the I/O address of the INDEX PORT

of the CONFIG PORT while CONFIG MODE is enabled.

Config Exit Key = < AAh>

5.8.3.3

Configuration Sequence Example

To program the configuration registers, the following sequence must be followed:

Enable Configuration State

Program the Configuration Registers

Disable Configuration State.

The following is an example of a configuration program in Intel 8086 assembly language.

;----------------------------.

; ENABLE CONFIGURATION STATE

;----------------------------'

MOV

DX,CONFIG_PORT_BASE_ADDRESS

MOV

AX,055H; Config Entry Key

OUT

DX,AL

;----------------------------.

; CONFIGURE BASE ADDRESS,

; LOGICAL DEVICE 8

;----------------------------'

MOV

DX,CONFIG_PORT_BASE_ADDRESS

MOV

AL,07H

OUT

DX,AL; Point to LD# Config Reg

MOV

DX,CONFIG_PORT_BASE_ADDRESS+1

Note:

The data read from the Configuration Port Data register is undefined when CONFIG MODE is not enabled.

TABLE 5-10:

CONFIGURATION PORT

Default I/O

Address

(Note 5-7)

Type

Relative Address

Default

Value

Notes

002Eh

Read / Write

INDEX

Configuration Port’s Base Address + 0

00h

Note 5-7

002Fh

Read / Write

DATA

Configuration Port’s Base Address + 1

00h

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