DP83905AVQB datasheet(14/80 Pages) NSC

14 / 80 page

40 Functional Description (Continued)

reads the next word in the EEPROM and appends this If in

8-bit mode it skips a word then reads and appends the next

word

Storing and Loading Configuration from EEPROM

If the EECONFIG pin is high during boot up the ATLANTIC

Controller’s configuration is read from the EEPROM before

the PROM data is read The configuration data is stored

within the upper two words of the EEPROM’s address

space Configuration Registers A and B are located in the

lower of these words Register C in the lower byte of the

upper word as shown in

Figure 10

To write this configuration into the EEPROM the user must

follow the routine specified in the pseudo code below This

operation will work regardless of the level on EECONFIG

The EELOAD bit of Configuration Register B being set starts

the EEPROM write process Care should be taken not to

accidently set the GDLINK bit and therefore disable link in-

tegrity checking The next 3 writes to this register load the

values that will be stored in the configuration register (note

that the last 2 of these writes do not have to follow the

normal practice of preceding a write to this register with a

read to this address) The ATLANTIC Controller will then

commence the EEPROM write The write has been com-

pleted when the EELOAD bit goes to zero This loading pro-

cedure should be followed exactly and interrupts should be

disabled until it has completed to prevent any accidental

accesses to the ATLANTIC Controller

EEPROM

LOAD()

DISABLE

INTERRUPTS()

value e READ(CONFIG

value e value AND 1 GDLINK

value e value OR EELOAD

WRITE(CONFIG

B value)

READ(CONFIG

WRITE(CONFlG

B config

for

WRITE(CONFIG

B config

for

WRITE(CONFIG

B config

for

while (value AND EELOAD)

value e READ(CONFIG

WAIT()

ENABLE

INTERRUPTS()

44 JUMPERED AND JUMPERLESS OPERATION

SUPPORT

The ATLANTIC Controller supports several options that

enable the implementation of either a ‘‘jumpered’’ or ‘‘jump-

erless’’ power on configuration when installed into a stan-

dard PC compatible’s ISA bus A wide range of options are

provided to ensure that the ATLANTIC Controller can be

configured by an end user to function in all possible PC-AT

system configurations Several types of configuration op-

tions can be implemented examples including

1 Full jumper options All programmable options are select-

ed by utilizing jumpers on the board Option selection

requires no special software An example of this is

shown in the

Figure 11

2 IO address jumpers only All other options configurable

via software This option simplifies installation while max-

imizing compatibility

3 Jumperless Special scheme provides contention-free

IO address selection

The ATLANTIC Controller’s Configuration Registers are

the key to providing the ability to implement various configu-

ration options These registers are configured by the same

method in shared memory and IO port modes 8- or 16-bit

modes The bit definitions of these registers are provided in

Section 5 All three registers are configured by hardware

selection during the Power-On-Reset of the system Two of

these registers can be configured via software (the Mode

Configuration Registers A and B) The third register (Hard-

ware Configuration Register C) is only configured during re-

set

The following table indicates

most of the ATLANTIC Con-

troller options that a designer may like to have user configu-

rable (This list does not represent the complete list For the

full list see the Configuration register descriptions in

Section 5)

TABLE I Some Configuration Options

for ATLANTIC Controller

Option

Selections

IO Base Address

0300H

02C0H

Software

0320H

0240H

0340H

0280H

0360H

Interrupt No

4 Interrupts

8 Interrupts

Boot PROM

Disabled

0CC00H

Address

0C000H

0D000H

0C400H

0D400H

0C800H

0D800H

0DC00H

Boot PROM Size

None

32k

16k

64k

Media Selection

Twisted Pair

Thin Ethernet

AUI Port

Architecture

IO Mode

Shared RAM

Mode

Bus Timing

IOCHRDY

MEM16 Mode

Options

Mode

The three basic options are described below Because of

the variety of programmable options there are a number of

variations possible only a few typical examples will be dis-

cussed

FULLY JUMPERED OPERATION

This option is shown in

Figure 11 In this configuration most

options are selected by jumpers on the ATLANTIC Control-

ler’s memory bus For this option all configuration options

are set upon power-on by the ATLANTIC Controller as de-

scribed in Section 42 Accessing the configuration registers

is unnecessary and the EEPROM need only contain the

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