DP83266VF National Semiconductor, DP83266VF Datasheet - Page 26

• Manufacturer Part Number: DP83266VF
• Description: IC MEDIA ACSS CTRL INTF 160PQFP
• Manufacturer: National Semiconductor

Specifications of DP83266VF

• Applications: *
• Voltage - Supply: 4.75 V ~ 5.25 V
• Package / Case: 160-BFQFP
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -
• Other names: *DP83266VF

5 0 Functional Description (Ring Engine)
5 7 3 Handling Reserved MAC Frames
A Reserved MAC frame is any MAC frame aside from Bea-
con and Claim frames Tokens are not considered MAC
frames even though their Format bit (FC FF) is the same as
for MAC frames
When a Reserved MAC frame (Other MAC) is received it
is treated as a Higher Claim If the Transmitter is in the
Claim state when a Reserved MAC frame is received the
Transmitter returns to the Idle state and then repeats the
next Reserved MAC frame received If the Transmitter is in
the Beacon state and a Reserved MAC frame is received
the Transmitter continues to transmit Beacon frames If the
Transmitter is in the Idle state the Reserved MAC frame is
repeated
5 8 RECEIVE BATCHING SUPPORT
The Ring Engine stores each received SA and compares
the incoming SA with the previous SA This may be used to
batch status on frames received from the same station
The SameSA signal is asserted when
1 The current and previous non-Void frames were not MAC
2 The size of the address of the current frame is the same
3 The SA of the current frame is the same as the SA of the
On MAC frames the Information fields are compared This
information may be useful to inhibit copying MAC frames
with identical information This is particularly useful for copy-
ing Claim and Beacon frames when new information is pres-
ent
The Same INFO signal is asserted when
1 The current and previous non-Void frames were both
2 The first four bytes of the INFO field of the current frame
The size of the address of MAC frames is not checked
5 9 IMMEDIATE FRAME TRANSMISSION
Immediate requests are used when it is desirable to send
frames without first capturing a token Immediate requests
are typically used as part of management processes for Er-
ror Isolation and Recovery Immediate requests are also
useful in full duplex applications Immediate requests are
serviced only when the station’s Ring Operational flag is
Zero (CTSR ROP
To transmit an Immediate request the request must first be
queued at the MA Request Interface If the Ring is not
operational (Ring Operational flag is not set) the request
will be serviced immediately If the Ring is operational
(Ring Operational flag is set) the request will be serviced
when the Ring becomes non-operational The Ring be-
comes non-operational as a result of a MAC Reset (Func-
tion MCRST is set to One) or any of the conditions causing
the Reset or Recovery Actions to be performed
frames
as the size of the address of the previous non-Void
frame
previous non-Void frame
MAC frames (not necessarily the same FC value)
is the same as the first four bytes of the INFO field of the
previous non-Void frame
e
0)
26
In addition to servicing an Immediate request from the Tx
Data State it is also possible to service Immediate requests
from the Tx Claim or Tx Beacon State When transmit-
ting from the Claim or Beacon state in addition to request-
ing an Immediate Transmission Service Class the RQCLM
or RQBCN signals must be asserted to indicate an Immedi-
ate Claim or Immediate Beacon request These requests will
only be serviced when in the Claim or Beacon state Entry to
the Tx Beacon State can be forced by setting bit BCN of
the Function Register to One Entry to the Tx Claim State
can be forced by setting bit CLM of the Function Register to
One
While in the Tx Claim or Tx Beacon state the Ring En-
gine will transmit internally generated Claim or Beacon
frames except when an Immediate Claim or Beacon request
is present at the MA Request Interface signal RQCLM or
RQBCN is asserted and a frame is ready to be transmitted
At least one internally generated Claim or Beacon frame
must be transmitted before an Immediate Claim or Beacon
request is serviced It is possible for the internally generated
frame to return before the end of the requested frame has
been transmitted To allow time for the requested frame(s)
to be transmitted before leaving the Claim or Beacon state
bit ITR (for Claim) or bit IRR (for Beacon) of the Option
Register should be set to One
While an Immediate request is being serviced (from any
state) if bit IRPT of the Option Register is set to One (Inhibit
Repeat option) all received frames (except Lower Claim
and My Beacon frames) are ignored and the Immediate
request continues Lower Claim and My Beacon frames
can also be ignored by setting bit IRR of the Option Regis-
ter
5 10 FULL DUPLEX OPERATION
The Ring Engine supports full duplex operation by
1 Suspending the Token Management and Token Recov-
2 Inhibiting the repetition of all frames and tokens (set Op-
3 Using the Immediate Service Class
Frames of any size may be transmitted or received subject
to the minimum length specified in Section 5 4
5 11 PARITY PROCESSING
Through Parity is supported on the internal data paths be-
tween any Request interface and any Indicate interface
Odd Parity is provided every clock on all data outputs and is
checked every clock on all data inputs Parity errors are not
propagated through the Ring Engine (from the MAC Re-
quest and PHY Indication interface to the PHY Request in-
terface or from the PHY Indication interface to the MAC
Indication interface) Parity errors are isolated and resolved
When parity is not used on an Interface the parity provided
by the Ring Engine for its outputs may be ignored For the
Ring Engine’s inputs the result of the parity check is used
only if parity on that Interface is enabled
Interface parity is enabled by setting the appropriate bit in
the Mode register Mode CBP for Control Bus Parity
Mode PIP for PHY Indication parity and Mode MRP for MAC
Request Parity A Master Reset (Function MARST) disables
parity on all interfaces
(Continued)
ery protocols (set Option IRR)
tion IRPT)