DP83266 datasheet(129/152 Pages) NSC

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70 Control Information (Continued)

INTERMEDIATE

0000

NONE

Non status is written This may be used by software to identify a NULL or invalid CNF

0001

Preempted

RCHN1 was preempted by RCHN0 RCHN1 will be serviced following RCHN0

0010

Part None

The MACSI device is servicing a Request but it cannot hold onto a token and the last frame of a

Requestpart has been transmitted

BREAKPOINTS

0011

Service Loss

The THT expired during a Request with THT enabled Only Occurs for Intermediate Confirmation

0100

Reserved

COMPLETION

0101

Completed Beacon

When transmitting from the Beacon state this status is returned when the Ring Engine receives a

Beacon When transmitting from the Claim state this status is returned when the Ring Engine wins the Claim

process

0110

Completed OK

Normal completion with good status

EXCEPTION COMPLETION

In all of the exception and error cases it is likely that at least some of the frames from the associated request were not

transmitted properly Therefore retransmission may be required In the case of bad confirmation 0111 the frames

may have been transmitted properly but lost on the ring A consistency failure 1110 means that there is a problem in

the request queues It is recommended that they be reinitialized The Internal or Abus error code 1111 is very severe

and it recommended that the MACSI device be reinitialized

0111

Bad Confirmation

This status is reported when there was an error during confirmation For confirmation the MACSI

device compares the returning frame to the Expected Frame Status (EFS) If these values do not match the ‘‘Bad

Confirmation’’ value is returned in the RS field If the transmitted frame does not return (My

Void Other

Void or

Token received instead) or if the ring state changes (MAC Reset or the Ring

Operational flag changes) the Bad

Confirmation value is also returned

1000

Underrun

This exception is caused when the memory interface does not allow the MACSI device to fill the transmit

data FIFO as quickly as it is being emptied It implies that the frame was aborted during transmission

1001

Host Abort

This exception is caused when the host software clears the SARABT bit to force an abort or when there is

not enough space in the confirmation (CNF) queue This implies that the Request did not complete normally

1010

Bad Ringop

This exception is reported when the Request Class for a Request object is incompatible with the current

ring state (ie Immediate class with an operational ring or Async Sync or restricted class when the ring state is non-

operational) The Request was aborted

1011

MAC Device Abort

This exception indicates that the MACSI device aborted the Request and asserted TXABORT

This could be from an interface parity error or because the transmitted frame failed the FC check or because the

MACSI device received a MAC frame while transmitting in the DATA state This status is also returned when the MACSI

device receives an Other

Beacon while transmitting in the Beacon state or when the Claim process is lost while

transmitting in the Claim state It implies that the Request did not complete normally

1100

Timeout

This exception code indicates that the TRT timer expired during the transmission of a Request with THT

disabled Normally the Ring Engine will finish the current frame and release the Token when the Token Holding Timer

(THT) expires However for certain requests the THT can be disabled In this case the Token Rotation Timer (TRT)

may expire because the station has made the Token Late The Ring Engine will abort the request and a Timeout will be

signaled to the System Interface

1101

MAC Reset

This code indicates that the MACSI underwent a MAC Reset during this request A MAC Reset can be

generated by software (ie requested via the control bus) or caused by hardware (the MACSI state machines entered

and illegal state) In either case the Request is aborted

1110

Consistency Failure

This code indicates that the MACSI device detected an inconsistency in the REQ or ODUD

descriptor queues For example if a frame started with on ODUDFirst it should be followed by an ODUDMiddle or

ODUDLast If the next ODUD was another ODUDFirst this would be a consistency error The Request is aborted when

a consistency error is detected

ERROR

1111

Internal or Fatal ABus Error

This exception is caused when the MACSI device detects an internal hardware error

(eg illegal state machine state) in the transmit logic while transmitting a frame It is also set when an ABus error

occurs during frame transmission It implies that the frame data may not have been transmitted properly

FIGURE 7-8 Request Status Field (RS) of CNF Descriptor

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DP83266 Datasheet(PDF) 129 Page - National Semiconductor (TI)

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