DM9008 datasheet(33/68 Pages) ETC

33 / 68 page

DM9008

ISA/Plug & Play Super Ethernet Contoller

Final

Version :DM9008-DS-F02

June 14, 2000

Software Protocol

The Plug and Play software sends the initiation Key to all Plug

and Play cards to place them into configuration mode. The

software is then ready to perform the isolation protocol.

The Plug and Play software generates 72 pairs of I/O read

cycles from the READ_DATA port. The software checks the

data returned from each pair of I/O reads for the 55H or AAH

driven by the hardware. If either 55H or AAH are read back,

then the software assumes that the hardware has a 1 bit in that

position. All other bits are assumed to be 0.

During the first 64 bits, software generates a checksum using

the received data. The checksum is compared with the

checksum read back in the last 8 bits of the sequence.

There are two other special considerations for software

protocol. During an iteration, it is possible that the 55H and

AAH combination is never detected. It is also possible that the

checksum does not match. If either of these cases occurs on

the first iteration, it must be assumed that the READ_DATA

port is in conflict. If a conflict is detected, then the

READ_DATA port is

relocated. The above process is

repeated until a non-conflicting location for the READ_DATA

port is found. The entire range between 200H and 3FFH is

available; however, in practice it is expected that only a few

locations will be tried before software determines that no Plug

and Play cards are present.

During subsequent iterations, the occurrence of either of these

two special cases should be interpreted as the absence of any

further Plug and Play cards (i.e. the last card was found in the

previous iteration). This terminates the isolation protocol.

NOTE: The software must delay 1 msec prior to starting

the first pair of isolation reads, and must wait

250

µsec between each subsequent pair of

isolation reads. This delay gives the ISA card

time

access

information

from

very

slow

storage devices.

On power up, all PnP cards detect RSTDRV, set their CSNs to

0, and enter the Wait fo Key state. There is a required 2 msec

delay from either a RSTDRV or PnP Reset command to any

Plug and Play port access. This allows a card to load initial

configuration information from a non-volatile device, which is

"9346" for DM9008.

Cards in the Wait for Key state do notacknowlege any access

to their auto-configuration ports until the Initiation Key is

detected, ignoring all ISA access to their Plug and Play

interface. When the cards have received the initiation key, they

enter the Sleep state. In this state, the cards listen for a

Wake[CSN] command with the write data set to 00H. This

wake[CSN] command will send all cards to the Isolation state

and reset the serial identifier/resource data pointer to the

beginning.

The first time the cards enter the Isolation state, it is necessary

to set the READ_DATA port address using the Set RD_DATA

port command. The software should then use isolation

protocol to check whether the selected READ_DATA port

address is in conflict with any other device.

Next, 72 pairs of reads are performed to the Serial Isolation

checksum read from the card is valid, then one card has been

isolated. The isolated card remains in the Isolation state, while

all other cards failing the isolation protocol are returned to

Sleep state. The CSN on the isolated card is set to a unique

number, causing this card to change to the Config state.

Sending a Wake[0] command causes this card to change back

to Sleep state, and all cards with a CSN value of zero to

change to the Isolation state. This entire process is repeated

until no Plug and Play cards are detected.

DM9008 Datasheet(PDF) 33 Page - List of Unclassifed Manufacturers

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