Cortex™-A8 Technical Reference Manual A.1. AXI interface

A.1. AXI interface

For complete descriptions of AXI interface signals, see the AMBA AXI Protocol Specification.

Table A.1 shows the AXI interface signals that have been added or that have different definitions for the Cortex-A8 processor.

Table A.1. AXI interface

Signal	I/O	Reset	Description
A64n128	I	-	Statically selects 64-bit or 128-bit AXI bus width: 0 = 128-bit bus width 1 = 64-bit bus width. This pin is only sampled during reset of the processor.
ACLKEN	I	-	AXI clock gate enable: 0 = AXI clock disabled 1 = AXI clock enabled. Note The rising edge of the internal ACLK signal comes two CLK cycles after the CLK cycle in which ACLKEN is asserted. See Chapter 10 Clock, Reset, and Power Control.
ARCACHE[3:0] and AWCACHE[3:0]	O	Undefined	Read or write cache type: b0000 = strongly ordered b0001 = device b0010 = reserved b0011 = normal noncacheable b0100 and b0101 = reserved b0110 = cacheable write-through, allocate on reads only b0111 = cacheable write-back, allocate on reads only b1000 to b1110 = reserved b1111 = cacheable write-back, allocate on both reads and writes.

Signal

I/O

Reset

Description

A64n128

Statically selects 64-bit or 128-bit AXI bus width:

0 = 128-bit bus width

1 = 64-bit bus width.

This pin is only sampled during reset of the processor.

ACLKEN

AXI clock gate enable:

0 = AXI clock disabled

1 = AXI clock enabled.

Note

The rising edge of the internal ACLK signal comes two CLK cycles after the CLK cycle in which ACLKEN is asserted. See Chapter 10 Clock, Reset, and Power Control.

ARCACHE[3:0]

and

AWCACHE[3:0]

Undefined

Read or write cache type:

b0000 = strongly ordered

b0001 = device

b0010 = reserved

b0011 = normal noncacheable

b0100 and b0101 = reserved

b0110 = cacheable write-through, allocate on reads only

b0111 = cacheable write-back, allocate on reads only

b1000 to b1110 = reserved

b1111 = cacheable write-back, allocate on both reads and writes.

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