dp83261 National Semiconductor Corporation, dp83261 Datasheet - Page 80

• Manufacturer Part Number: dp83261
• Description: Bmac Device Fddi Media Access Controller
• Manufacturer: National Semiconductor Corporation

TKRCVD
EDRCVD
FRSTRP
FOERROR
MACRST
Symbol
VDL
VFCS
7 0 Signal Descriptions
7 3 2 4 Termination Event
The terminating event for all PDUs is provided in the PDU Status signals
When a token is terminated by a valid Ending Delimiter (TT symbol pair) the TKRCVD signal is asserted When a frame is
terminated by a valid Ending Delimiter the EDRCVD is asserted and remains asserted until all frame status has been passed to
the MA Indicate Interface Every PDU is terminated by one of the following
Symbol
7 3 2 5 Termination Status
When a valid Ending delimiter is received after a valid starting delimiter the termination status signals provided the results of the
Frame validity check and the Frame Check Sequence Check
The received values of the control indicators are presented in the data stream while EDRCVD is asserted
1 A valid Ending Delimiter (TKRCVD or EDRCVD)
2 An IDLE symbol indicating that the frame was stripped by another station (FRSTRP)
3 A symbol other than data Idle or an Ending Delimiter indicating that a Format Error occurred (FOERROR)
4 A MAC Reset (MACRST)
Pin
68
67
Pin
69
66
71
70
72
I O
O
O
I O
O
O
O
O
O
Valid Data Length Indicates that a frame meeting the minimum length requirements of the Standard
and of an even number of symbols was received This signal is valid with EDRCVD
Valid Frame Check Sequence Indicates that a frame with the standard CRC was received This signal
is valid with EDRCVD
Token Received Indicates that the Ending Delimiter for a valid token is being received
Ending Delimiter Received Indicates that the Ending Delimiter for a frame is being received The
values of the received Status Indicators are available through the MID byte stream on this and
subsequent cycles while this signal is asserted
Frame Stripped Indicates that an Idle symbol was received while expecting part of a PDU This
usually indicates that the PDU was stripped by an upstream station This signal may be asserted
anytime during reception of a frame after RCSTART is asserted
Format Error Indicates that a Format Error (non-DATA IDLE or Ending Delimiter Symbol) was
detected This signal may be asserted anytime during reception of a frame including with RCSTART
for the next frame
MAC Reset Indicates that a MAC Reset has been issued This signal is asserted as a result of a
software or hardware reset or internal errors This signal is asserted whenever bit MCRST of the
Function Register is set This signal may be asserted anytime
(Continued)
80
Description
Description