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Message
From: Billditt@a...
Date: Wed, 13 Feb 2002 01:14:14 EST
Subject: Re: [ethmac] AMBA AHP Interface
I believe ARM has the AMBA specification available via their
website.
Its a good specification, I have a couple of recommendations:
1. Dont sweat split transactions
2. Dont sweat wrapping bursts
3. Watch the size vs bytes selects.
Many busses do byte/word/Dword alignment using bytesels.
AMBA doesnt. AMBA uses size and address to align transfers.
For instance, for 32 bit AMBA bus, transferring 3 bytes of a 4 byte
Dword. AMBA breaks these up into 2 transfers, a word (with aligned
address) and a byte (with byte aligned address).
This becomes kind of a pain when you are going from a bytesel based system
to AMBA. And if you are doing bursts (most busses do) , its an even bigger
pain. But AMBA is the most used SOC bus today, so I guess we live with it.
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