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AHB Multilayer

Jesuraj vinoth Joseph
Offline over 6 years ago
Note: This was originally posted on 30th April 2008 at http://forums.arm.com

In the multilayer environment,  i found a interconnect matrix with interface signals on the Master side having a hsel signal. Can anyone specify the significance of it. A basic doubt is that apart from the interconnect matrix do we hav any slave mux and decoder.
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  • 0 Offline over 6 years ago
    Note: This was originally posted on 12th May 2008 at http://forums.arm.com

    Hi Saurabh,

    The AHB protocol described in the "AMBA 2" spec is a multi-master bus, so there are HBUSREQ and HGRANT signals for the masters to request and be granted control of the bus. The spec also allowed slaves to give SPLIT or RETRY responses to avoid one transfer stalling the bus if there would be lots of wait states.

    The AHB-lite protocol described in the "AMBA 3" group of specs is a single master bus, so much simpler than the full AHB spec described in "AMBA 2". AHB-lite does not have the HBUSREQ and HGRANT signals, and as SPLIT and RETRY were only applicable to multi-master buses, these too have been removed.

    I think the "AMBA 3" AHB-lite spec is really intended for either very simple designs, or much more complex multi-layer AHB designs where there is only a single master on each layer of the design (so not needing the complexity of "AMBA 2" AHB), but with lots of layers then having access to shared slaves.

    All of the AMBA specs should be available from ARM's website, so after a quick look there I can see the AMBA 3 specs are at [url="http://www.arm.com/products/solutions/axi_spec.html"]http://www.arm.com/products/solutions/axi_spec.html[/url]

    Not sure about release notes though, what sort of info are you looking for that would be in a release note ?

    JD
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  • 0 Offline over 6 years ago
    Note: This was originally posted on 12th May 2008 at http://forums.arm.com

    Hi Saurabh,

    The AHB protocol described in the "AMBA 2" spec is a multi-master bus, so there are HBUSREQ and HGRANT signals for the masters to request and be granted control of the bus. The spec also allowed slaves to give SPLIT or RETRY responses to avoid one transfer stalling the bus if there would be lots of wait states.

    The AHB-lite protocol described in the "AMBA 3" group of specs is a single master bus, so much simpler than the full AHB spec described in "AMBA 2". AHB-lite does not have the HBUSREQ and HGRANT signals, and as SPLIT and RETRY were only applicable to multi-master buses, these too have been removed.

    I think the "AMBA 3" AHB-lite spec is really intended for either very simple designs, or much more complex multi-layer AHB designs where there is only a single master on each layer of the design (so not needing the complexity of "AMBA 2" AHB), but with lots of layers then having access to shared slaves.

    All of the AMBA specs should be available from ARM's website, so after a quick look there I can see the AMBA 3 specs are at [url="http://www.arm.com/products/solutions/axi_spec.html"]http://www.arm.com/products/solutions/axi_spec.html[/url]

    Not sure about release notes though, what sort of info are you looking for that would be in a release note ?

    JD
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