DP83266 datasheet(123/152 Pages) NSC

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70 Control Information (Continued)

Bit

Symbol

Description

Word 0

(Continued)

D15 – D12

CNFCLS

Confirmation Class

(Continued)

D15

Repeat

Enables repeated transmission of the first frame of the request until the request is aborted

This may be used when sending Beacon or Claim frames

Fetch all frames of REQ

Repeat transmission of first frame of REQ

A Request may use Repeat on RCHN1 and have a Request loaded on RCHN0 but not vice-versa

Specifically when a Request with the Repeat option is loaded on RCHN0 RCHN1 must not have any

REQs active or visible to the MACSI device Thus REQs on RCHN1 may be queued externally but the

queue’s Limit Register must not be set at or after that point Requests with the Repeat option should

only be used on one Request Channel at a time and preferably on RCHN0

Note that the Repeat Option requires a REQFirst Descriptor The Repeat Option will not work on a

REQOnly Descriptor

D23 – D16

SIZE

Size

Count of number of frames represented by the ODUD stream pointed to by REQLOC field

Descriptors with a null frame count are permitted and are typically used to end a Request without

having to send data For example to end a restricted dialogue a REQLast with SIZE e 0 will cause

the Request Machine to command the Ring Engine to capture and release the specified classes of

token The response of the MACSI device to REQs with SIZE e 0 is as follows

1 REQFirst MACSI device latches the REQ Descriptor fields then fetches the next REQ

RQRCLS is asserted but RQRDY remains deasserted

2 REQMiddle MACSI device fetches the next REQ

3 REQOnly MACSI device requests the capture of the appropriate token When it is captured the

MACSI device asserts RQFINAL and ends the request

4 REQLast MACSI device captures the token asserts RQFINAL then marks the request

complete

D29 – D24

UID

User Identification

Contains the UID field from the current REQFirst or REQOnly

D31 – D30

RES

Reserved

Word 1

D27 – D0

LOC

Location

Bits 272 are the memory word address of the ODUD stream Bits 10 are expected to

be 00 and are not checked

D29 – D28

RES

Reserved

D31 – D30

F-L

FirstLast Tag

Identifies the REQ stream part ie Only First Middle or Last FL e 10 e First FL

00 e Middle FL e 01 e Last FL e 11-Only

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