Copyright © ARM Limited. 2001, 2004. All rights reserved.
ARM DVI 0045B
Multi-layer AHB
Overview
This overview describes the functionality of the multi-layer AHB in the following
sections:
• Preliminary material on page 1-2
• Introduction on page 1-3
• Implementation on page 1-4
• Advanced options on page 1-5
• Example implementation on page 1-8.
Overview Multi-layer AHB
2 Copyright © ARM Limited. 2001, 2004. All rights reserved. ARM DVI 0045B
1 Preliminary material
Copyright © 2001, 2004 ARM Limited. All rights reserved.
1.1 Release information
Changes to this document are listed in
Table 1.
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1.5 Web address
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Table 1 Change history
Date Issue Change
16 March 2001 A First issue
10 May 2004 B Second issue
Overview Multi-layer AHB
ARM DVI 0045B Copyright © ARM Limited. 2001, 2004. All rights reserved. 3
2 Introduction
Multi-layer AHB is an interconnection scheme, based on the AHB protocol, that
enables parallel access paths between multiple masters and slaves in a system. This is
achieved by using a more complex interconnection matrix. Key advantages are:
• You can develop multi-master systems with an increased available bus bandwidth.
• You can construct complex multi-master systems that have a flexible architecture.
This removes the requirement to fix design decisions about the allocation of
system resources to particular masters at the hardware design stage.
• You can use standard AHB master and slave modules without requiring
modification.
• Each AHB layer can be very simple because it only has one master, so no
arbitration or master-to-slave muxing is required. These layers can use the
AHB-Lite protocol, meaning that they do not have to support request and grant,
or retry and split transactions.
• The arbitration effectively becomes point arbitration at each peripheral and is
only necessary when more than one master wants to access the same slave
simultaneously.
• The only hardware you have to add to the standard AHB transport infrastructure
is the multiplexor block to connect the multiple masters to the peripherals.
• Because the multi-layer architecture is based on the existing AHB protocol, you
can reuse previously-designed masters and slaves without modification.
Figure 1 shows a block diagram of the basic multi-layer concept.
Figure 1 Basic multi-layer concept
Interconnect
matrix
Slave
Slave
Slave
Slave
Master
Master
