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From: Benny Simonsen<bsi@e...>
Date: Wed Nov 14 10:59:05 CET 2007
Subject: [oc] WB standard, WB Builder: ACK connection in intercon
Hello,

I am wondering how to handle ACK in intercon.

Question:
Is it enough to "or" all ACK_O from all slaves and feed the result
to the active master?

Environment:
- Shared bus interconnect
- Registered feedback

Background:
Permission 4.15, Rule 4.15 in Wishbone standard B.3
Slave may set ACK_O w.o. checking STB_I, when registered feedback.
ACK_O is only valid when STB_I is set.

This gives that ACK_O from all slaves should be muxed, so that only
ACK_O from the selected slave is used, or am I wrong?

Examples:
Figure A22 just "or" the signals together
Wishbone Builder also just "or" the signals together
- but are those systems registered feedback systems?
- or don't it give any difference in intercon depending on classic
or registered feedback?

Note: The case is the same for RTY and ERR.

Best regards
Benny Simonsen
ETI A/S