IXP46X datasheet(25/148 Pages) INTEL

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Intel® IXP45X and Intel® IXP46X Product Line of Network Processors

August 2006

Datasheet

Document Number: 306261-004US

Datasheet—Intel® IXP45X and Intel® IXP46X Product Line of Network Processors

The programming priority of the MCU is for the Memory Port Interface to have the

highest priority and two AHB ports will have the next highest priority. For more

information on MCU arbitration support and configuration see the Intel® IXP45X and

Intel® IXP46X Product Line of Network Processors Developer’s Manual.

One item to be aware of is that when ECC is being used, the memory chip chosen to

support the ECC must match that of the technology chosen on the interface. Therefore,

if x8 in a given configuration technology is chosen then the ECC memory chip must be

the same. If a x16 configuration is chosen then a x16 chip must be used for the ECC

chip.

3.1.9

Expansion Interface

The expansion interface allows easy and — in most cases — glue-less connection to

peripheral devices. It also provides input information for device configuration after

reset.

Some of the peripheral device types are SRAM, flash, ATM control interfaces, and DSPs

used for voice applications. (Some voice configurations can be supported by the HSS

interfaces and the Intel XScale® processor, implementing voice-compression

algorithms.)

The expansion interface functions in two modes of operation:

• Legacy (16-bit, data mode)

• Enhanced (32-bit, data mode)

3.1.9.1

Expansion Bus Legacy Mode of Operation

In the legacy mode of operation, the expansion interface is a 16-bit interface that

allows an address range of 512 bytes to 16 Mbytes, using 24 address lines for each of

the eight independent chip selects.

Accesses to the expansion bus interface is completed in five phases. Each of the five

phases can be lengthened or shortened by setting various configuration registers on a

per-chip-select basis. This feature allows the IXP45X/IXP46X network processors to

connect to a wide variety of peripheral devices with varying speeds.

The expansion interface supports Intel or Motorola* microprocessor-style bus cycles.

The bus cycles can be configured to be multiplexed address/data cycles or separate

address/data cycles for each of the eight chip-selects.

Additionally, Chip Selects 4 through 7 can be configured to support Texas Instruments*

HPI-8 or HPI-16 style accesses for DSPs.

The expansion interface is an asynchronous interface to externally connected chips.

However, a clock must be supplied to expansion interface of the IXP45X/IXP46X

network processors for the interface to operate. This clock can be driven from GPIO 15

or an external source. The maximum clock rate that the expansion interface can accept

in legacy mode of operation is 66 MHz. If GPIO 15 is used as the clock source, the

Expansion Bus interface can only be clocked at a maximum of 33.33 MHz. GPIO 15’s

maximum clock rate is 33.33 MHz.

By providing this legacy mode of operation, code developed for previous generations of

this platform becomes easily portable.

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