Intel IXP43X manual Electrical Interface, Topology, @33 MHz, TSU = 7 nSec

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Hardware Design Guidelines—Intel®IXP43X Product Line of Network Processors

6.0PCI Interface Design Considerations

The IXP43X network processors have a single, 32-bit PCI device module that runs at 33 MHz. This chapter describes some basic guidelines to help design hardware that interfaces with PCI devices.

The PCI module is compatible with the PCI Local Bus Specification, Rev. 2.2. For a complete functional description and physical requirements, see the PCI Local Bus Specification, Rev. 2.2.

6.1Electrical Interface

The electrical definition is restricted to 3.3 V signaling environment. The device is not 5 V tolerant. All devices interfacing with the PCI module must operate at 3.3 V.

6.2Topology

Interfacing devices must be connected in a daisy-chain topology. When more than one device is in the bus, connecting stubs must be kept as short as possible.

There is a limitation to the number of devices connected to the internal arbiter. If more than four devices are required to be connected, an external arbiter is required.

The system time budget must be satisfied for 33 MHz cycles. The following equation and timing parameters must be met while routing a board that interfaces with a single PCI device or up to four devices as shown in Figure 23.

TCYC ≥ TVAL +TPROP + TSKEW + TSU

where:

TVAL = Valid Output Delay

TPROP = Bus Propagation Delay (maximum time for complete flight) TSKEW = Total Clock Skew

TSU = Input Setup Time

@33 MHz

TCYC = 30 nSec

TVAL = 11 nSec

TPROP = 10 nSec	TSKEW = 2 nSec

T SU = 7 nSec

When defining the maximum length of segments A and B as shown in Figure 23, the calculation must:

•Include an additional trace length segment from the PCI connector to the input device within the expansion PCI card

•Assume the segment to be 1.5 inch

•Use trace propagation delay of 150 to 190 ps/in as specified by the PCI standard

	Intel® IXP43X Product Line of Network Processors
April 2007	HDG
Document Number: 316844; Revision: 001US	67

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Contents Hardware Design Guidelines Intel IXP43X Product Line of Network ProcessorsHDG Intel IXP43X Product Line of Network ProcessorsApril Contents Figures Tables Document Number 316844 Revision 001US Date Revision Description § §001 Initial release HDG Chapter Name Description Content OverviewTerm Explanation Related DocumentationAcronyms List of Acronyms and Abbreviations Sheet 1List of Acronyms and Abbreviations Sheet 2 OverviewHDG Intel IXP435 Network Processor Block Diagram Typical Applications System Memory Map System Architecture DescriptionIntel IXP43X Product Symbol Description Soft Fusible FeaturesSignal Type Definitions Soft Fusible Features Sheet 1Ethernet Soft Fusible Features Sheet 2USB Host Each USB can be Enable separately DDRII/I Sdram InterfaceName Device-Pin Connection Terminatio Description Field Signal InterfaceDDRII/I Sdram Interface Pin Description Sheet 1 TypeDDRII/I Sdram Interface Pin Description Sheet 2 DDRII/I Sdram InitializationExpansion Bus Expansion Bus Signal Recommendations Sheet 1Type Pull Name Recommendations Field Down Name Type Pull Recommendations Field Down Reset Configuration StrapsExpansion Bus Signal Recommendations Sheet 2 Boot/Reset Strapping Configuration Sheet 1Boot/Reset Strapping Configuration Sheet 2 MHz Setting Intel XScale Processor Operation Speed3 8-Bit Device Interface Intel XScale Processor Cfg0 Cfg1 Cfgenn Actual Core Speed4 16-Bit Device Interface 16-Bit Device Interface Flash InterfaceFlash Interface Example Uart InterfaceUart Signal Recommendations Uart Interface Example MII InterfaceMII NPE a Signal Recommendations Signal Interface MIIMII NPE C Signal Recommendations Sheet 1 MAC Management Signal Recommendations NPE a and NPE C MII NPE C Signal Recommendations Sheet 2Device Connection, MII MII Interface Example Gpio InterfaceUSB Interface Gpio Signal RecommendationsDesign Notes Name Type Pull Description Field Down USB Host Signal RecommendationsCommon Mode Choke Host Device Utopia Level 2/MIIA Utopia Level 2 InterfaceType Pull Name Description Field Down Utpopfci UTPOPDATA4UTPOPDATA75 UTPOPADDR40ETHARXDATA30 Etharxclk ClavUtpipfci UtpipsocUTPIPADDR40 UTPIPDATA5UTPIPDATA6 UTPIPDATA7Device Connection HSS InterfaceHSSRXDATA0 High-Speed, Serial InterfaceHSSTXDATA0 HSSTXCLK0HSS Interface Example SSP InterfaceSynchronous Serial Peripheral Port Interface Serial Flash and SSP Port SPI Interface Example PCI InterfacePCI Controller Sheet 1 Pciclkin PCI Interface Block DiagramPCI Controller Sheet 2 PciintanType Option Description Name Device-Pin Connection Field Connect signal to same pin between PCI Parity Two devicesPCI Option Interface PCI Host/Option Interface Pin Description Sheet 1Type Option Name Device-Pin Connection Description Field On the Option device, these signals are notSignal PCIREQN0 to one PCIREQN30 inputs to the Host PCI Host/Option Interface Pin Description Sheet 2PCI Host/Option Interface Pin Description Sheet 3 Jtag InterfaceClock Oscillator Clock SignalsClock Signals Input System ClockRecommendations for Crystal Selection Power Supply PowerNominal Name Voltage Description VCC Decoupling Power SequenceReset Timing Decoupling Capacitance Recommendations§ § Component Selection Component PlacementPCB Overview General RecommendationsStack-Up Selection Component Placement on a PCBControlled-impedance traces Low-impedance power distribution Layer Stackup General Layout Guidelines General Layout and Routing GuideGeneral Component Spacing Signal Changing Reference PlanesGood Design Practice for VIA Hole Placement Pad-to-Pad Clearance of Passive Components to a PGA or BGA Clock Signal ConsiderationsUSB V2.0 Considerations MII Signal ConsiderationsCrosstalk EMI Design Considerations Power and Ground PlaneTrace Impedance § § Tcyc = 30 nSec Tval = 11 nSec Tprop = 10 nSec Electrical InterfaceTopology @33 MHzPCI Address/Data Routing Guidelines Clock DistributionParameter Routing Guidelines PCI Clock Routing Guidelines Trace Length LimitsRouting Guidelines Signal LoadingIntroduction Ddrii / Ddri SdramDcasn / Ddrcasn DDRII/I Signal GroupsGroup Signal Name Description Drasn / DdrrasnDDR Sdram Sizea Supported Ddri 32-bit Sdram ConfigurationsSupported Ddrii 32-bit Sdram Configurations Supported Ddri 16-bit Sdram ConfigurationsTechnology Arrangement Banks Supported Ddrii 16-bit Sdram ConfigurationsDDRII/DDRI Rcomp and Slew Resistances Pin Requirements Address Size Leaf Select TotalDdrii OCD Pin Requirements DDR-II Symbol Parameter Units Min MaxDDR Clock Timings DDR Sdram Write Timings Symbol Parameter Minimum Nominal Maximum Units DDRII-400 MHz Interface -- Signal TimingsPrinted Circuit Board Layer Stackup DDR II/I Sdram Interface -- Signal TimingsSymbol Parameter Minimum Nom Maximum Units Timing RelationshipsGroup Signal Name Length mil Signal Package Lengths Sheet 1Timing Relationships Signal Package Lengths Sheet 2 Clock Group Signal Package Lengths Sheet 3Parameter Definition Data and Control GroupsDCB70/DDRCB70, DDQ310 / DDRDQ310 Ddrii Data and Control Signal Group Routing GuidelinesSignal Group Members Ddrii Command Signal Group Routing Guidelines§ §