DM9008F View Datasheet(PDF) - Davicom Semiconductor, Inc.
Part Name
Description
MFG CO.
'DM9008F' PDF : 68 Pages View PDF
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.
DM9008
ISA/Plug & Play Super Ethernet Contoller
NOTE: The software must delay 1 msec prior to starting
the first pair of isolation reads, and must wait
250 sec between each subsequent pair of
isolation reads. This delay gives the ISA card
time to 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 not acknowlege 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
register to isolate a card, as previously described. If the
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.
Final
33
Version: DM9008-DS-F02
November 30, 2000
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