21154 PCI-to-PCI Bridge
Specification Update
July 2004
Notice: The 21154 may contain design defects or errors known as errata which may cause the
behavior of the 21154 to deviate from published specifications. Current characterized errata are
documented in this specification update. Order Number: 278295-017
21154 PCI-to-PCI Bridge Specification Update
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21154 PCI-to-PCI Brid ge Specification Update iii
Contents
Revision History......................................................................................... 5
Preface....................................................................................................... 8
Summary Table of Changes..................................................................... 10
Identification Information.......................................................................... 14
Errata ....................................................................................................... 15
Specification Changes ............................................................................. 22
Specification Clarifications....................................................................... 23
Documentation Changes ......................................................................... 24
21154 PCI-to-PCI Bridge Specification Update Intel Confidential5
Revision History
Date Version Description
July 2004 017 Updated Errata 9. description.
2/25/05 016
The following changes have been made in this version:
• Updated status for Errata 7. and Errata 9. on page 11.
• Revised Pin 1 Designator Change description in “Specification Changes” on
page 11.
• Added Errata 10. “Secondary Address pins are driven incorrectly during
reset.” on page 21.
• Added documentation change “Updated Version of PCI Local Bus
Specification” on page 36.
3/1/02 015
The following changes have been made in this Specification Update:
•Updated Errata table st atus column on page 11. Updated status for Erratas 1
through 6.
•Added Recommendation #1 fix for Errata 6 “Secondary Clocks Outputs
s_clk_o<9:0> May Not Start-up Properly Under Some Conditions”. Moved
previously existing fix recommendation for Errata 6 to become the second
recommendation.
•Added Errata 9, “21154AE/BE May Experience Performance Problems or
Hangs when P_VIO = 3.3V” on page 20.
•Updated Specification Clarification 1 title des cript ion on page 23.
•Updated links in this document.
6/25/01 014 Updated Errata #1 description in Table , “Errata” on page 11 and added new
worst-case conditions tables for Tval description,Section 1 on page 15
6/8/01 013 Updated Errata #1 titl e descr iption in Table , “Errata” on page 11 and added
worst-case conditions for Tval description,Section 1 on page 15
6Intel Confidential 21154 PCI-to-PCI Bridge Specifica t ion Update
Revision History
5/8/01 012
Added information for AE and BE versions of the 21154 product
Updated Errata #5 AC Marking state in Table , “Errata” on page 11
Updated status state for Errata #4, #5, #6, and #8 in Table , “Errata” on page 11
and in descriptions in “Errata” on page 15
Updated descriptions for Errata #1 and #3 in Table , “Errata” on page 11
Added last two rows to Table 1, “21154 Markings” on page 14
Updated description for “Tval Timing Issues When Running at 66 MHz for All PCI
Signals. Tval timing improved on the 21154BE.” on page 15
Updated description for “Hold Time Issues for All PCI Signals (Both Bused and
Control) on the 21154.” on page 16
Added changes #2, #3, and #4 in “Specification Changes” on page 22
Added toTable , “Documentation Changes” on page 13 that include:
•“Updated Version of PCI Local Bus Speci fication” on page 35
•“Section 4.1, Updated s_clk and p_clk description” on pa ge 35
•“Section 4.2, Updated Clock Outputs” on page 35
•“Section 4.4.1, Added Note at End of Section.” on page 35
•“Section 4.5, Table 5 Product Part Numbers have been updated.” on
page 36.
Note: These documentation changes have been implemented in
Version 003 of the 21154 PCI-to-PCI Bridge Hardware
Implementation Application Note.
4/30/01 011
The Steppings columns in the “Errata” table, “S pecification Changes” table, and
“Specification Clarifications” on page 11 were changed to Markings to more
accurately reflect the revisions of the component.
Errata #3 (Setup Issues With PCI Control Signals When Running at 66 MHz on
the 21154B C) of this Specification Update was found to be invalid and is now
listed as Fixed.
The term “REV_ID6” was removed from the problem section of Errata 3, Setup
Issues With PCI Control Signals When Running at 66 MHz on the 21154BC. on
page 16.
Errata 7, GPIO 66 MHz T iming May Cause Secondary Clocks to be Disabled was
added.
Errata 8, Bus Conflict Occur s During Configuration on AGP Port of Some Chip
Sets. was added.
Documentation Changes 12, Section 10.2, Secondary Clock Control, Figure 19,
15, and 18, Section 4.4.1, Serial Clock Mask Shift, Figure 3 were modified, and
documentation change 15, Section 10.2.1, Mask and Load Shift T iming Events for
66 MHz Operation was added.
12/15/00 010
Documentation changes 17, 18, and 19, referenced the wrong document number.
The correct document number has been updated in the Summary Table of
Changes. All references to the 21554 have been changed to 21154. Figures in
documentation changes 13 and 20 have been updated. Errata 3 now has
stepping C included as an errata in the Summary Table of Changes.
11 /13/ 00 009 Corrected speed settings for 211 54AB /AC /BC Markings.
10/02/00 008 Added errata 6.
Date Version Description
21154 PCI-to-PCI Bridge Specification Update Intel Confidential7
Revision History
9/18/00 007
Modified description of trst_l, tms and tdi signal, added a new section on JTAG
testing. Modified the description of the trst_l specification clarification. Modified
order of serial stream in Figure 20, Clock Mask and Load Timing. Added note for
pull-up resistor for output clocks. Added specification change to PBGA package
dimensions for coplanarity maximum value. Added documentation changes 21
and 22: descriptions of two signals when secondary bus speed set for 66 MHz.
2/7/00 006
Modified order of serial stream in table 34, gpio Serial Data format. Modified the
description for Dword bit 0. Modified Figure 19, Example of gpio Clock Mask
Implementation on the System Board. Modified Figure 20, Clock Mask and Load
Shift Tim ing. Clarified definition of trst_l signal.
12/14/99 005 Modified description of the clamp circuit errata. Added 64-bit data bus width
errata.
9/1/99 004 Added documentation change item 6 for 66 MHz operation. Updated Hold time
errata. Added clamp circuit errata.
8/11/99 003 Tsetup test conditions found to be invalid. Device meets 3 ns Tsetup limit on all
pins.
7/29/99 002 Added updated boundary scan order pin list.
7/19/99 001 This is the new Specifica tion Update document. It contains all identified errata
published prior to this date.
Date Version Description
8Intel Confidential 21154 PCI-to-PCI Bridge Specifica t ion Update
Preface
Preface
This document is an update to the specifications contained in the Affect ed Documents/Related
Documents table below. This document is a compilation of device and documentation errata,
specification clarifications and changes. It is intended for hardware system manufacturers and
software developers of applications, operating systems, or tools.
Information types defined in Nomenclature are consolidated into the specification update and are
no longer publ i shed i n ot her d ocum ent s. Thi s docu ment may also co nt ain i nf ormati on t hat wa s n ot
previously published.
Affected Documents/Related Documents
Title Order
21154 PCI-to-PCI Bridge Datasheet 278108
21154 PCI-to-PCI Bridge Configuration Application Note 278080
21154 PCI -to-PCI Bridge Hardware Implementation Application Note 278081
21154 PCI-to-PCI Bridge Evaluation Board User’s Guide 278133
21154 PCI-to-PCI Bridge Specification Update Intel Confidential9
Preface
Nomenclature
Errata are design defects or errors. These may cause t he 21154 PCI -to-PCI Bri dge’s beha vior to
deviate from published specifications. Hardware and software designed to be used with any given
stepping must ass ume that all errata documented for that stepping are present on all devices.
Specification Changes are modifications to the current published specifications. These changes
will be incorporated in any new release of the specification.
Specification Clarifications describe a specification in greater detail or further highlight a
specification’s impact to a complex design situation. These clarifications will be incorporated in
any new release of the specification.
Documentation Chang es include typos, errors, or omissions from the current published
specifications. These will be incorporated in any new release of the specification.
Note: Errata remain in the specification update throughout the product’s life cycle, or until a particular
stepping is no longer commercially availab le. Under these circumstances, er rata remov ed fr om the
specification update are archived and available upon request. Specification changes, specification
clarifications and documentation changes are remov ed from the specification update when the
appropriate changes are made to the appropriate product specification or user documentation (data
sheets, manuals, etc.).
10Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Summary Table of Changes
Summary Table of Changes
The following table indicates the errata, specification chang es, specification clarifications, or
documentation changes which apply to the 21154 PCI-to-PCI Bridge product. Intel may fix some
of the errata in a future stepping of the component, and account for the other outstanding issues
through documentation or specification changes as noted. This table uses the following notations:
Codes Used in Summary Table
Stepping
X: Errata exists in the stepping indicated. Specification Change or
Clarification that applies to this stepping.
(No mark)
or (Blank box): This erratum i s fixed in lis ted s t eppin g or specification change does n ot
apply to listed st epp i ng.
N.A. Not applicable.
Page
(Page): Page location of item in this document.
Status
Doc: Document change or update will be implemented.
Fix: This erratum is intended to be fixed in a future step of the component.
Fixed: This erratum has been previously fi xed.
No Fix: There are no plans to fix this erratum.
Row
Change bar to left of table row indicates this erratum is either new or
modified from the previous version of the document.
21154 PCI-to-PCI Bridge Specification Update Intel Confidential11
Summary Table of Changes
Errata
No. Markings Page Status ERRATA
AB AC BC AE BE
1N/A N/A X N/A X 15 No Fix Tval Timing Issues Wh en Running at 66
MHz for All PCI Signals. Tval timing
improved on the 21154BE.
2XXXXX16 No Fix Hold Time Issues for All PCI Signals (Both
Bused and Control) on the 21154.
316Fixed Setup Issues With PCI Control Signals
When Running at 66 MHz on the 21154BC.
4XX 16 Fixed Clamp Circuit May Not Function Properly
Under All Conditions
5XXX 17 Fixed 64-Bit Data Bus Wid th not Maintained when
Tr ansitioning from PCI Bus Power
Management States D3 to D0
6XX 17 Fixed Secondary Clocks Outputs s_clk_o<9:0>
May Not Start-up Properly Under Some
Conditions
7N/A N/A X N/A X 19 No Fix GPIO 66 MHz Timing May Cause
Secondary Clocks to be Disabled
8N/A N/A X 20 Fixed Bus Conflict Occurs During Configuration
on AGP Port of Som e Ch ip Sets.
9XX20 No Fix 21154AE/BE May Experience Performance
Problems or Hangs when P_VIO = 3.3V
10 XX21 No Fix Secondary Address pins are driven
incorrectly during reset.
Specification Changes
No. Markings Page Sta tus SPECIFICATION C HANGES
AB AC BC AE BE
1XXXX22 Doc
PBGA Package Dimensions for
Coplanarity Changed from Maximum
Value 0.15 mm to Maximu m Value of 0.2
mm
2XX22 Doc PCI Configuration Space Registers have
changed.
3XX22 Doc Pin 1 Designator Change
4XX22 Doc Power Management Capability Change
12Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Summary Table of Changes
Specification Clarifications
No. Markings Pa ge Status SPECIF I C ATION C LA RIFIC ATIONS
AB AC BC AE BE
1XXXXX23 Doc Signal trst_l must be driven low to disable
JTAG for normal operation
21154 PCI-to-PCI Bridge Specification Update Intel Confidential13
Summary Table of Changes
Documentation Changes
No. Document Revision Page Status DOCUMENTATION CHANGES
1278108 24 Doc Section 17.2, Table 40, Absolute Maximum Ratings
2278108 24 Doc Section 18.0, Paragraph 1
3278108 24 Doc Section 18.0, Figure 25, 304-Point 2-Layer PBGA
Package
4278108 24 Doc Section 18.0, Table 51, 304-Point 2-Layer PBGA
Package Dimensions
5278108 25 Doc Section 16.2, Table 39, Boundary Scan Order
6278133 28 Doc Section 4.3, Paragraph 1
7278108 28 Doc Section 16.7, Initialization, Paragraph 1
8278081 28 Doc Section 5.1, Initialization, Description
9278081 29 Doc Section 6.3.1, Signal trst_l Pull-Down Resistor, New
Section
10 278108 29 Doc Section 2.10, JTAG Signals, Table 13
11 278080 30 Doc Section 5.0, System Initialization, Last Paragraph
12 278108 30 Doc Section 10.2, Secondary Clock Control, Figure 19
13 278108 30 Doc Section 10.2, Secondary Clock Control, Figure 20
14 278108 31 Doc Section 10.2, Secondary Clock Control, Table 34
15 278108 31 Doc Section 10.2.1, Mask and Load Shift Timing Events for
66 MHz Operation
16 278080 32 Doc Section 15.1.3, Primary Command Register, Table
Description
17 278081 33 Doc Section 4.4.1, Serial Clock Mask Shift, Table 4
18 278081 33 Doc Section 4.4.1, Serial Clock Mask Shift, Figure 3
19 278081 34 Doc Section 4.4.1, Serial Clock Mask Shift, Figure 4
20 278081 34 Doc Section 4.2, 21154 Output Clocks
21 278108 35 Doc Section 18.0, Table 51, 304-Point 2-Layer PBGA
Package Dimensions
22 278108 35 Doc Section 2.5, Secondary Bus Arbitration Signals, Table 8
23 278108 35 Doc Section 2.9, Miscellaneous Signals, Table 12
24 278081 35 Doc Updated Version of PCI Local Bus Specification
25 278081 35 Doc Section 4.1, Updated s_clk and p_clk description
26 278081 35 Doc Section 4.2, Updated Clock Outputs
27 278081 35 Doc Section 4.4.1, Added Note at End of Section.
28 278081 36 Doc Section 4.5, Table 5 Product Part Numbers have been
updated.
29
278108
278080
278081
278133
36 Doc Updated Version of PCI Local Bus Specification
14Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Identifica ti on Infor mat ion
Identification Information
Markings
The 21154 is a legacy component that was initially introduced by Digital Sem iconductor, a
bus i ness division of Dig ital E quipmen t Corporation. The characteristics are described in Table 1.
Table 1. 21154 Markings
Package Markings REV_ID
Register
Valuea
a. Identified in a PCI system by reading the value in the REV_ID register.
Package Type Speed (MHz) Stepping
Digital Semiconductor
21154AA DC1062B 01h 304PBGA 33 B
Digital Semiconductor
21154AB DC1062C 02h 304PBGA 33 C
Intel 21154AC DC1113A 05h 304PBGA 33 A
Intel 21154BC DC1113A 05h 304PBGA 66 A
Intel 21154AC DC1113B 05h 304PBGA 33 B
Intel 21154BC DC1113B 05h 304PBGA 66 B
Intel FW21154AE 00h 304PBGA 33 E
Intel FW21154BE 00h 304PBGA 66 E
21154 PCI-to-PCI Bridge Specification Update Intel Confidential15
Errata
Errata
1. Tval T iming Issues Wh en Running at 66 MHz for Al l PCI Signal s. T val ti ming
improved on the 21154BE.
Problem: This problem exists for parts with REV_ID 5 and REV_ID 0.
Two worst-case s lo w con di ti ons exi st. The 21 154 BC an d 2 1154B E were tested under tw o di fferent
sets of worst-case sl ow conditions.
Table 2. Definition of Worst Case Slow Conditions
Table 3. Comparison of the 21154BC and the 21154BE Performance
Implication: This miss for Tval on PCI control signals may reduce total flight time (Tprop) when running at
66 MHz. The 21154BE meets or exceeds the 21154BC performance under the worst-case slow
conditions.
Note: The FW21154BE wors t case slow condition 2 includes the very slow processing corner, 108 o C
junction temperature, no airflow, 4 layer coupon, 3.0 V Vdd, and bus switched data (all 1s and all
0s flowing upstream from a fully loaded secondary) with no interrupts. Any improvement in the
thermal factors (Oja), board design, Vdd, data transition density, and interrupt densit y and Tval
will be < 6.0 ns at 85 o C junction temperature.
Workaround: There are no workarounds fo r this erratum.
Note: Refer to the 21154 PCI-to-PCI Bridge Specification Update Errata table for current errata. All
errata listed are fixed in the 21154AE/BE version except for Errata #1, #2, and #7 .
Status: No Fix: See “Summary Table of Changes” on page 10.
Worst-Case Slow Ttest [Tj] (oC) Process V ariati on
(Intel Defined) Vdd (V)
Condition 1 85 S - slow 3.0
Condition 2a
a. The FW21154BE worst case slow condition 2 includes the very slow processing corner, 108 o C junction
temperature, no airflow, 4 layer coupon, 3.0 V Vdd, and bus switched data (all 1s and all 0s flowing upstream
from a fully loaded secondary) with no interrupts. Any improvement in the thermal factors (Oja), board des ign,
Vdd, data transition density, and interrupt density and Tval will be < 6.0 ns at 85 o C junction temperature.
108 SS - very slow 3.0
Product Worst-case Slow
Condition Tval V_V (ns) Tval Z_V (ns)
21154BC 1 6.5 8.0
21154BC 2 No data No data
21154BE 1 <6.4 <6.25
21154BE 2 7.35 7.35
16Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Errata
2. Hold Time Issues fo r All PCI Si gnals (Both Bu sed and Control) on the 21154.
Problem: Th is problem exists for parts with REV_ID 2, REV_ID 5 and REV_ID 0.
The PCI Local Bus Specification, Revision 2.2, specifies a Hold time of 0 ns i n Section 7.6.4 .2. The
21154AB requires a minimum hold time of 1.4 ns. Both the 21154AC/BC and 21154AE/BE
require a minimum hold time of 1.375 ns.
Implication: Most PCI devices will functio n properly with this difference to the Hold time specification.
Workaround: There are no workarounds for this erratum.
Status: No Fix: See “Sum mar y Table of Changes ” on page 10.
3. Setup Issues Wi th PCI Control Signals When Running at 66 M Hz on the
21154BC.
Problem: Th is problem was originally believed to exist for parts with REV_ID 5.
Setup time issues on the following 66 MHz PCI control signals: p_frame_l, p_irdy_l, p_trdy_l,
s_frame_l, s_irdy_l, s_trdy_l. The PCI Local Bus Specification, Revision 2.2, specifies a Setup
time of 3 ns for all devices when running at 66 MHz in Section 7.6.4.2. The 21154BC requires a
minimum worst-case setup time of 4.5 ns.
Implication: The Tsetup specification miss on PCI control signals must be considered in the overall timing
budget for designs that use this product, and may reduce total flight time (Tprop) when running at
66 MHz.
Workaround: This errata was caused by a test-fixture problem and is invalid .
Status: Fixed
4. Clamp Circuit May Not Function Properly Under All Conditions
Problem: This problem has been found on parts with REV_ID 5. When either the pri mary or secondary vio
pins are connected to 3.3 volts, the 21154’s clamping circuit may not function properly.
Implication: Dependent on the application environment, oscillations or “ringing” have been observed on some
PCI control signals (for example, STOP#). The circuitry to generate the input clamp voltages of
both the 21154AC and 21154 BC is different than that of the 21154AB.
Workaround: When the application topology allows it (short bus lengths, di rect etch runs), connecting 3.3 volts
to these pins should produce desired results. The use of p_vio and s_vio for both the 21154AC and
21154BC will be determined by the customer application. Designs that adhere to the “Expansion
Board Specification” of the PCI Local Bus Specification, Revision 2.2 are not affected. Designs
whose topology might include long bus lengths might find that connecting s_vio or p_vio to 5 volts
leads to improved signal integrity for the corresponding bus. As such, Intel recommends t horough
signal integrity analyses prio r to a decision on which voltag e to connect to these pins.
If there is any 5-volt PCI device on a bus segment, the vio pin for that segment should be tied to the
5 volt supply.
Status: Fixed
21154 PCI-to-PCI Bridge Specification Update Intel Confidential17
Errata
5. 64-Bit Data Bus Width not Maintained when Transitioning from PCI Bus
Power Management States D3 to D0
Problem: When transi tioning from PC I Bus Power Management states D3 hot to D0 hot, the 21154 performs
an internal reset of the primary bus circuits and clears the REQ64 status of the primary bus. The
secondary bus continues to operate at 64-bit data bus width but the primary bus width reverts back
to a 32-bit data bu s width. The 21154 drives the AD<63:32> wi th whatever data i s next in its qu eue
and may drive incorrect parity for AD<63:32> as well.
Implication: The 21154 can cause bus contention on AD<63:32> resulting in data corruption and device
damage. This erratum may also cause so me systems to hang or report parity errors.
Workaround: This problem can b e avo i ded by tr eat ing t h e 21154 as a PCI Bu s Po w er Manag ement leg acy d e vice
by not using the PCI Bus Power Managemen t capabilities.
Status: Fixed
6. Secondary Clocks Outputs s_clk_o<9:0> May Not Start-up Properl y Unde r
Some Conditions
Note: This errata only applies to applications that use the 21154 for secondary clocks.
Problem: This probl em has been found on the 21154AC and 21154BC. Under repeat ed and frequent power
cycling, the secondary clock circuits may not power up in the proper state, resulting in the device
not coming out of reset after power up.
Implication: In a system with a 21154AC or 21154BC that has one of its s_clk_o<9:0> outputs fed back to
provide the s_clk, it is possible that the s_clk_o<9:0> output cl ocks will be dri ven a nd rem ain low,
keeping s_rst_l asserted, during system power up.
This happens occasionally when a latch whose output disables the serial shift registers on the
Secondary clock control powers up in a high state and the shift register bit corresponding to the
s_clk_o<9:0> output that is fed back also powers up in the high state.
Workaround: Two workarounds are provided for this errata:
•The first i s the recommended workaround which ensure proper operation of the secondary
clock outputs s_cl k _0<0 :9>.
•The second wor karound ensures the secondary clo ck ou t put s operate properly but co uld res ul t
in contention between the s_ckl_0 output and the buffer.
1. Figure 1 illu strates the first recommendation - a circuit where an on-board pulse source is
gated via the B0 input of the multip lexer to the S_Clock_in pin of the 21150.
At time 0, the S input of the multiplexer is low, allowing pulses from the on-bo ard puls e
source, conn ected to t he B0 inpu t, to be p rovided t o the 21150 S_C lk inpu t pin. When t he time
determined by the R/C network is satisfied, the S input pin will be in a logic High state. The
multiplexer will then shut off the input pulse from S0 and will direct the S_Clock_out pulses
via the B1 multiplexe r inp ut, into S_Clock_in
The values used for the R/C network should be selected to allow a minimum of 2 pulses to be
delivered to the 21 150 after Vdd has reached 3.0V at a frequency not to exceed the appropriate
PCI componen t. i.e. 30 n s for a 33Mhz bridge. Thes e values sho uld be chose n based on the rise
time of the power supply and the freque ncy of the o n b oard pu lse s ource. Th e v alu es given fo r
R1, R3, and C1 are for example purposes only.
18Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Errata
Note:The NC7SB3157 2:1 Multiplexer / Demultiplexer Bus Switch used in this example has a
maximum propagation del ay of 800ps that should be taken into consideration when
matching trace lengths of the clock lines to avoid introducing excessi ve skew in the
clocks. All S_Clock etch length s must be matched to within 2ns @ 33Mh x or 1n s
@66Mhz. The addition of this circuit requires that the etch length for the S_clock_in
signal be reduced to compensate for the 800ps delay.
2. In the second recommendation, to guarantee the proper initialization of the s_clk circuits, th e
addition of an external circuit that provides a m in im um of two transitio ns on the s_clk input
during the power-up ramp is necessary. This can be done using a solution that drives an
external clock onto the s_clk input while 3.3V Vcc is ramping during power up.
Figure 2 illustrates the use of a tristable buff er to provid e multip le pulses to the s_clk input.
The Vcc ramp rate and R1,C1 time constant determine the duration and amplitude of the
pulses generated during power up. The R2-R3 values are chosen based on applicable board
etch impedance-matching requirements.
Figure 1. S_Clock Multiplex er Workaround Circuit for Errata 6.
A9661-01
21154
NC7SB3157
C1
.02 uF
R1
47K
9
R3
68K
9
R2
33
9
S
S_Clk_in
S_Clk_out
A
B0
B1
21154 PCI-to-PCI Bridge Specification Update Intel Confidential19
Errata
The following should be considered in calculating the R1,C1 time constant:
— Make the time constant of the circuit as short as possible, while still ensuring that a
minimum of two pulses are generat ed during the Vcc ramp.
— Phase delay between s_clk_o and the external clock should be minimized.
— Matching the external clock and s_clk_o frequencies to reduce contention.
— Laborat ory experiments using p_clk as the external clock and a R1C1 time constant
between 40 and 60 percent of the Vcc ramp have been successful u sing this co nfiguration.
However the use of p_clk as the external clock violates the PCI bus specification for
loading of the primary clock.
Status: Fixed
7. GPIO 66 MHz Timing May Cause Secondary Clocks to be Disabled
Problem: In the Secondary Clock Control function, the msk_in pin may be used with an external shift
register to selectively disable secondary clock output pins. At 66 MHz the timing of the inte rface
between the gpio pins and the external shift register may cause some secondary clock outputs to be
incorrectly disabled.
The setup time o f the recommended 74F166 shift register is not compatible with the timing of the
gpio<2>, and gpio<0> outputs of the 21154 PCI-to-PCI bridge. Pin gpio<2> driving the shift
register load/shift enable (PE#), does not provide the necessary setup time for the gpio<0>. Signal
gpio<0> is used as a clock to in itiate the parallel l oad of the 74F166 shi ft register data inputs. The
timing is referred to as Tgsval.
Note: This errata does not apply when operating at 33 MHz or if the external shift regi ster is not used an d
msk_in is grounded enabling all secondary clocks.
Figure 2. Recommended Circ uit for a Tristable Buffer
A8363-
01
R1
R3
VCC
C1
S_CLK
External
Clock
S_CLK_O
R2
20Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Errata
Implication: At 66 MHz the setup time mismatch between the shift register parallel inputs and PE# pin and gp io
pins may cause the shift register to be incorrectly loaded. This could result in the secondary clocks
to be incorrectly disabled.
Workaround: In order to provide an appropriate setup time, a buffer must be added to delay gpio<2> with respect
to gpio<0>. This buffer (or buffers) pr ovides the delay for gpio<2> to correctly load the parallel
data inputs of 74F166 registers. A setup time of at least 3ns is required at the shift register for PE#
to load.
Note: For more information, see Section 10.2.1, Mask and Load Shift Timing Events for 66 MHz
Operation in this specification update.
Status: No Fix
8. Bus Conflict Occurs During Configuration on AGP Port of Some Chip Sets.
Problem: The 21154 Bridge accepts type zero configuration cycles on its primary bus. It also accepts Type 1
configuration cycl es on its primary bus and forwards them, if they are addressed to a bus number
between its secondary and subsequent bus numbers, which are assigned to the bridge by system
software. The secondary and subsequent bus number registers are set to zero by reset. Some
chipsets supporting AGP use Type 1 confi guration cycles to program themselves. The chipset has
set its own address to be bus 0, device 0. Unfortunately, this creates a conflict if the bridge's
downstream b us numb er regi s ters have no t yet been programmed to a non-zero value. This confl ic t
occurs when both the chipset and bridge respond to Type One Configuration cycles to bus 0
resulting in bus contention.
Implication: Both the AGP interface and the 21154 Bridge will respond to the same Type 1 bus transaction
causing bus signal contention.
Workaround: None
Status: Fixed
9. 21154AE/BE May Experience Performance Problems or Hangs when P_VIO
= 3.3V
Problem: Intel has received reports of performance problems due to excessive retries and hangs in a few
applications when P_VIO and/or S_VIO =3.3V. The retry issue has been observed in several types
Video, Fi bre Chan nel and G igabit E thernet m odul es with th e time to failu re ranging from 7 minutes
to 39 hours.
The symptom of this issue is that a delayed read is initiated on the primary bus. It is immediately
responded to with re try and sto red as a CAM entry. The request is played out o n the second ary b us
and the device receives the data. The CAM entry becomes corrupt due to noise on the core ground.
This causes the read request on the primary bus to match the CAM entry, but the bridge does not
respond with the data. As the CAM entry is matched, no additio nal read request is made on the
secondary bus, but the primary bus never receives the data, only retries. This causes the initiat ing
master to continue to retry the read, making no progress. Th e 21154 will eventually discard that
read data when the pri mary master timeout timer expires (210 or 215 clock cycles). The delayed
read transaction is then reinitiated on the primary bus and usually completes normally. This causes
a 30.7 µs or 983 µs d elay (at 33MHz) depending on the setting of the primary master timeo ut bit.
The same issue and scenar io has also been reported on delayed r eads from th e secondary bus to the
primary bus.
The root cause is due to changes in the internal grounding scheme implemented in the
21154AE/BE - an approximate 400mV reduction in the noise immunity occurred in the CAM
circuitry. The data sto r ed wit hin th e CAM (Content Address able Memory) ci rcuit ry becom es
21154 PCI-to-PCI Bridge Specification Update Intel Confidential21
Errata
corrupted resulting in a mismatch when the transaction is retried causing the transaction to be
retried continuously. The primary master timeout timer times out (210 or 215 clock cycles), discards
the data, and reinitiates the transaction on the next cycle. This transaction usually completes as a
normal delayed read transaction.
Since the 21154 is a highly symmetrical device and t he CAM circuitry is duplicated on both the
primary and secondary interfaces the issue may occur on either an ups tream or downstream
delayed read transactions.
Implication: Applications using P_VIO and/or S_VIO=3.3V may experience excessive retries due to a
reduction in noise immunity in the CAM section of the chip. When P_VIO and/or S_VIO is set
above ~3.8V the biasing of the input transistor effectively reduces the resulting core ground
undershoot that is coupled through the ESD protection clamp.
This issue has on ly been reported in a very small num ber o f h igh p erfo rman ce app lications su ch as
Video cards, Gigabit Ethernet and 100MByte/s Fibre Channel with P_VIO and/or S_VIO set to
3.3V. Other lower performance applications and implementations with P_VIO and S_VIO set to
5V have not reported the issue. This may also manifest as a layout sensitivity issu e.
Workaround: Setting P_VIO and S_VIO to 5V has proven to eliminate these issues on current designs. Many
21154 designs that implemented the errata 4 work around are already biasing the P_VIO and
S_VIO pins to 5V and should not experience the issues.
Note:P_VIO and S_VIO pins set the value of the voltage clamp only and
has no affect on the signaling levels of the bus.
Status: No Fix
10. Secondary Address pins are driven incor rectly during reset.
Problem: During reset S_AD <63:0>, C/BE# and PAR are driven high. The PCI Local Bus Specification
requires that these pins be driven low during reset.
Implication: In applications where multiple PCI components implemented on the secondary bus may drive the
bus during reset, there is a potential for device co ntention if the 21154AE/BE is driving high and
the other device/devices are driving low. This contention may cause excessive power dissipation in
the 21154 and could potentially damage the device.
Workaround: There is no known wo rk around.
Status: No Fix
22Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Specification Changes
Specification Changes
1. PBGA Package Dimensions for Coplana rity Changed from Maximum Value
0.15 mm to Maximum Value of 0.2 mm
Per PCN notification 961, the 304-point 2-layer PBGA package dimensions for symbol aaa,
coplanarity, are changed from maximum value 0.15 mm to maximum value 0.2 mm.
Note: The following changes (2-4) are specific to the 21154AE/BE version of the product only.
2. PCI Configuration Space Registers have changed.
Table 1. Register Changes
3. Pin 1 Designator Change
Viewing the text label printed on top of the 21154AE/BE package (marking side), the Pin 1
designator appears in the lower left hand corner of the package. The Pin 1 designator for previous
steppings was located in the upper left hand corner of the package.
Note: The pin designations have not changed. The only change was that the printed label was rotated 90o.
4. Power Management Capability Change
The pmeena_l pin was changed on the 21154AE/BE to indicate that devices on the secondary side
of the bridge do not support the PME# pin. It is up to the software then to scan the device to
actually determine PME# pin support. This is described in Table 2 that follows:
Table 2. Power Management Capability Changes
Register Offset Old Value New Value
Vendor ID 00:01 1011h 8086h
Device ID 02:03 0026h B154h
Revision ID 08 05h 00h
Description Value
Pin Number D11
Previous Name Vdd
Previous Function Power Input
New Name pmeena_l
Function Input
Operation This can be tied to either Vdd or Vss (ground). This effects the value of bits [31:27],
PME_SUP, of the Power Management Register (dword address DCh, offset DEh).
Vdd These 5 bits should read a 00000a, as in previous steppings.
a. 00000 indicates that the device behind the bridge does not support PME#.
Vss These 5 bits should read as 11111.
21154 PCI-to-PCI Bridge Specification Update Intel Confidential23
Specification Clarifications
Specification Clarifications
1. Signal trst_l must be driven low to disable JTAG for normal operation
The signal trst_l resets the JTAG circuitry while asserted low. This signal also enables normal
JTAG TAP cont rol ler op eration when hi gh. Fo r n ormal PC I-to- PCI b ridge opera tion, disab le JTAG
by pulling trst_l low using a 5K resistor.
24Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Documentation Changes
Documentation Changes
1. Section 17.2, Table 40, Absolute Maximum Ratings
Maximum power P wc is changed from 2.2W to 2.9W.
2. Section 18.0, Paragraph 1
Section 18.0. Paragraph 1 is changed to read as follows:
The 21154 variants are contained in the 304-point plastic ball grid array (PBGA) packages shown
in Figure 25. The 21154AC/BC and 21154AE/BE variants utilize a 4-layer 304-point PBGA. All
other variants utilize a 2-layer 304-point PBGA.
3. Section 18.0, Figure 25, 304-Point 2-Layer PBGA Package
Section 18.0, Figure 25 title is changed to read as follows:
304-Point PBGA Package (2-Layer and 4-Layer)
4. Section 18.0, Table 51, 304-Point 2-Layer PBGA Package Dimensions
Section 18.0, Table 51 title is changed to read as follows:
304-Point PBGA Package Dimensions (2-Layer and 4-Layer)
Table 40. Absolute Maximum Ratings
Parameter Minimum Maximum
Junction temperature, T j— 125oC
Maximum voltage applied
to signal pins —5.5 V
Supply voltage, V cc —3.9 V
Maximum Power, P wc —2.9 W
Storage temperature range, T sg -55oC 125oC
21154 PCI-to-PCI Bridge Specification Update Intel Confidential25
Documentation Changes
5. Section 16.2, Table 39, Boundary Scan Order
The boundary-scan order pin call outs change from pin R4 through pin R21. The correct pin call
out is:
Table 39. Boundary Scan Order (Sheet 1 of 3)
Pin Number Signal Name Boundary Scan Order By Group Disable Group Disable Cell
R4 bpcce NA/127 —
NOTE: A new signal, bpcce, was added on pin R4 for the 21154AB and later revisions. From pin R4 through
pin R21, two values are provided in the xxx/yyy format: the boundary-scan register number in the xxx
field is for the 21154AA version only, and the boundary-scan register number in the yyy field is for the
21154AB and later revisions.
T3 p_clk 127/128 —
T2 Vss 128/129 — Group Disable 3
U3 p_req_l 129/130 3
U2 p_ad<31> 130/131 2
U4 p_ad<30> 131/132 2
U1 p_ad<29> 132/133 2
V2 p_ad<28> 133/134 2
V1 p_ad<27> 134/135 2
V3 p_ad<26> 135/136 2
W2 p_ad<25> 136/137 2
W1 p_ad<24> 137/138 2
Y2 p_cbe_l<3> 138/139 2
Y1 p_idsel 139/140 —
W4 p_ad<23> 140/141 2
Y3 p_ad<22> 141/142 2
AA1 p_ad<21> 142/143 2
AA3 p_ad<20> 143/144 2
Y4 p_ad<19> 144/145 2
AB3 p_ad<18> 145/146 2
AA4 p_ad<17> 146/147 2
Y5 p_ad<16> 147/148 2
AC4 Vss 148/149 — Group Disable 2
AB4 p_cbe_l<2> 149/150 2
AA5 p_frame_l 150/151 1
AC5 p_irdy_l 151/152 1
AB5 p_trdy_l 152/153 1
AA6 p_devsel_l 153/154 1
AC6 p_stop_l 154/155 1
AB6 p_lock_l 155/156 1
—V
ss 156/157 — Group Disable 1
26Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Documentation Changes
AC7 p_perr_l 157/158 1
Y7 p_serr_l 158/159 1
AB7 p_par 159/160 0
AA7 p_cbe_l<1> 160/161 0
AB8 p_ad<15> 161/162 0
AA8 p_ad<14> 162/163 0
AC9 p_ad<13> 163/164 0
AB9 p_ad<12> 164/165 0
AA9 p_ad<11> 165/166 0
AC10 p_ad<10> 166/167 0
AB10 p_m66ena 167/168 0
AA10 p_ad<9> 168/169 0
Y11 p_ad<8> 169/170 0
AC11 p_cbe_l<0> 170/171 0
AB11 p_ad<7> 171/172 0
AA11 p_ad<6> 172/173 0
AA12 p_ad<5> 173/174 0
AB12 p_ad<4> 174/175 0
AB13 p_ad<3> 175/176 0
AA13 p_ad<2> 176/177 0
Y13 p_ad<1> 177/178 0
AA14 p_ad<0> 178/179 0
AB14 p_ack64_l 179/180 0
AC14 p_req64_l 180/181 0
AA15 p_cbe_l<7> 181/182 0
AB15 p_cbe_l<6> 182/183 0
Y15 p_cbe_l<5> 183/184 0
AC15 p_cbe_l<4> 184/185 0
AA16 p_ad<63> 185/186 0
AB16 p_ad<62> 186/187 0
AA17 p_ad<61> 187/188 0
AB17 p_ad<60> 188/189 0
Y17 p_ad<59> 189/190 0
AB18 p_ad<58> 190/191 0
AC18 p_ad<57> 191/192 0
AA18 p_ad<56> 192/193 0
AC19 p_ad<55> 193/194 0
AA19 p_ad<54> 194/195 0
Table 39. Boundary Scan Order (Sheet 2 of 3)
Pin Number Signal Name Boundary Scan Order By Group Disable Group Disable Cell
21154 PCI-to-PCI Bridge Specification Update Intel Confidential27
Documentation Changes
AB20 p_ad<53> 195/196 0
Y19 p_ad<52> 196/197 0
AA20 p_ad<51> 197/198 0
AB21 p_ad<50> 198/199 0
AC21 p_ad<49> 199/200 0
AA21 p_ad<48> 200/201 0
Y20 p_ad<47> 201/202 0
AA23 p_ad<46> 202/203 0
Y21 p_ad<45> 203/204 0
W20 p_ad<44> 204/205 0
Y23 p_ad<43> 205/206 0
W21 p_ad<42> 206/207 0
W23 p_ad<41> 207/208 0
W22 p_ad<40> 208/209 0
V21 p_ad<39> 209/210 0
V23 p_ad<38> 210/211 0
V22 p_ad<37> 211/212 0
U23 p_ad<36> 212/213 0
U20 p_ad<35> 213/214 0
U22 p_ad<34> 214/215 0
U21 Vss 215/216 — Group Disable 0
T23 p_ad<33> 216/217 0
T22 p_ad<32> 217/218 0
T21 p_par64 218/219 0
R22 config66 219/220 —
R21 msk_in 220/221 —
Table 39. Boundary Scan Order (Sheet 3 of 3)
Pin Number Signal Name Boundary Scan Order By Group Disable Group Disable Cell
28Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Documentation Changes
6. Section 4.3, Paragraph 1
Section 4.3, Paragraph 1 is changed to read as follows:
Some versi ons of t he 21154 su pport 66 MHz oper ation. Versions ma rked 21154Ax are not t ested t o
be 66 MHz capable. Versions of the 21154 marked 21154Bx are capable of 66 MHz operati on.
7. Section 16.7, Initialization, Paragraph 1
This section has been changed to:
The test access port controller and the instruction register output latches are initialized and JTAG is
disabled while the trst_l input is asserted low. While signal trst_l is low, the test access port controller
enters the test-logic reset st ate. This results in the ins truction regi ster bei ng res et whic h holds t he
bypass register i nstructio n. During te st-logic r eset st ate, all JTAG test logic is disabl ed and the device
performs normal f unctions. The test access port controll er leaves thi s state only after t rst_l ( low) goes
high and an appropriate JTAG test operat ion sequ en ce is se nt on t he tms and t ck pi ns.
For the 21154 to operate properly, the JTAG logic must be reset. There ar e two ways to reset this
logic:
•The controller will reset asynchronously with the assertion of TRST_L.
•The controller will reset synchronously after five TCK clock cycles, with TMS held high.
Note: During normal 21154 operation the JTAG logic must be disabled by pulling trst_l low using a 5K
resistor.
8. Section 5.1, Initialization, Description
This section has been changed to:
The test access port contro ller and th e instruction register ou tput latches are initialized and JTAG is
disabled while the trst_l input is ass e rted low (see Figure 5). While signal trst_l is low, th e test
access port controller enters the test-logic reset state. This results in the instruction register being
reset which holds the bypass register instruction. During test-logic reset state, all JTAG test logic is
disabled, and the device perfo rms normal function s. The test access p ort con troller leaves th is state
only afte r trs t_l (lo w) g oes hig h and an appr opr iate JTA G tes t operati on s equence is sent on the tms
and tck pins.
For the 21154 to operate properly, the JTAG logic must be reset. There ar e two ways to reset this
logic:
•The controller will reset asynchronously with the assertion of trst_l.
•The controller will reset synchronously after five TCK clock cycles, with TMS held high..
Note: During normal 21154 operation the JTAG logic must be disabled by pulling trst_l low using a 5K
ohm resistor.
Figure 5. Signal trst_l States
A7805-01
trst_l JTAG Reset JTAG Enabled
21154 PCI-to-PCI Bridge Specification Update Intel Confidential29
Documentation Changes
9. Section 6.3.1, Signal trst_l Pull-Down Resistor, New Section
The following new section has been added:
A 5 K Ω pull-down resis tor is requir ed on trs t_l for normal PCI-to-PC I bridg e opera tion. However,
some JTAG test results may be inconclusiv e if the 5 K Ω resistor remains in the circuit. To obtain
accurate JTAG results, Intel recommends one of the following solutions:
•Verify th at th e JTAG test equipment, after driving trst_l low to reset the TAP controller,
constantl y drives trst_l high during JTAG tests. If th i s sign al is not cons ta ntl y driven high, the
5 K Ω resistor will pull the signa l to a low state.
•Remove the 5 K Ω resistor during JTAG tests. This resistor must be installed during normal
PCI-to-P CI bridg e operati on.
•Design external circuits with a switch or jumper to isolate the 5 K Ω resi st or du ring JTA G tes ts
(see Figure 6). This switch must enable the resistor during normal PCI-to-PCI bridge
operation.
10. Section 2.10, JTAG Signals, Table 13
The descripti on for trst _ l has been change d as follows:
Figure 6. Removal of Pull-Down Resistor for JTAG Testing
A7821-01
21154
50K Ω
VDD
5K Ω
Switch
or Jumper
trst_l
Table 13. JTAG Signals
Signal Name Type Description
tdi I
JTAG serial data in. Signal tdi is the serial input through which JTAG instru ctions
and test data enter the JTAG interface. The new data on tdi is sampled on the
rising edge of tck. An unterminated tdi is pulled high by a weak pull-up resistor
internal to the device.
tms I JTAG test mode select. Signal tms causes state transitions in the test access port
(TAP) controller. An unterminated tms is pulled high by a weak pull-up resistor
internal to the device.
trst_l I
JTAG TAP reset and disable. When asserted low, JTAG is disabled and the TAP
controller is asynchronously forced to enter a reset state, which in turn
asynchronously initializes other test logic. An unterminated trst_l is pulled high by a
weak pull-up resistor internal to the device. The TAP controller must be reset
before the JTAG circuits can function. For normal JTAG TAP port operation, this
signal must be high.
For normal PCI-to-PCI bridge operation of the device, this signal must be pulled
low using a 5K resistor.
30Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Documentation Changes
11. Section 5.0, System Initialization, Last Paragraph
The last paragraph in this section has been changed to:
For information on initializing JTAG, see the 21154 PCI-to-PCI Bridge Hardware Implementation
Application Note.
12. Section 10.2, Secondary Clock Control, Figure 19
This figure now appears as follows:
13. Section 10.2, Secondary Clock Control, Figure 20
This figure now appears as follows:
Figure 19 Example of GPIO Clock Mask Implementation on the System Board
A7804-02
21154
74F166
CE#
CP
MR#
PE#
prsnto#<0>
prsnto#<1>
prsnto#<0>
prsnto#<1>
prsnto#<0>
prsnto#<1>
prsnto#<0>
prsnto#<1>
Ds
D7
msk_in
s_clk_<9>
gpio<0>
gpio<2>
vSS
vSS
D6
D5
D4
D3
D2
D1
D0
74F166
vCC
vCC
Q7
Q7
CE#
CP
MR#
PE#
D7
D6
D5
D4
D3
D2
D1
D0
Figure 20. Clock Mask and Load Shif t Timing
A7803-01
gpio[0]
gpio[2]
msk_in Bit 15 Bit 14
21154 PCI-to-PCI Bridge Specification Update Intel Confidential31
Documentation Changes
14. Section 10.2, Secondary Clock Control, Table 34
This table has been re-arranged to indicate the gpio serial data format. It now appears as follows:
15. Section 10.2.1, Mask and Load Shift Ti ming Events for 66 MHz Operation
The following new section has been added:
The following list provides the timing sequence for 66 MHz operation for an example circuit as
shown in Figure 19 and the timin g diagram in Figure 21.
1. The gpio<2> original coming from the 21154 does not provide 3ns setup time needed to
provide the parallel load enable PE# of the 74F166.
2. The shi f ted gpio<2> is delayed by ~9ns to provide ample setup time to enable the parallel of
the shift register connected to pin 15 of the 74F166.
3. Bit 15 input D6 of the shift register is pulled high, to Vcc.
4. Bit 14 input D7 is pulled high, to Vcc. These signa ls are not u sed internally in the 21154.
5. Bit 13 s_clk_o<9> is a feedback to t he 21 154 s_clk_o input. To enable s_clk_o<9> in all cases
the D5 input of the shift register is grounded, to Vss.
6. Bit 12 s_clk_o<8> is disabled.
7. Bit 11 s_clk_o<7> is disabled.
8. Bit 10 s_clk_o<6> is disabled.
9. Bit 9 s_clk_o<5> is di s abl ed .
Table 34. GPIO Serial Data Format
Bit Description s_clk_o Output
<15:14> Reserved Not applicable
<13> 21154 s_clk input 9
<12> Device 8 8
<11> Device 7 7
<10> Device 6 6
<9> Device 5 5
<8> Device 4 4
<7:6> Slot 3 PRSNT#<1:0> or device 3 3
<5:4> Slot 2 PRSNT#<1:0> or device 2 2
<3:2> Slot 1 PRSNT#<1:0> or device 1 1
<1:0> Slot 0 PRSNT#<1:0> or device 0 0
32Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Documentation Changes
16. Section 15.1.3, Primary Command Register, Table Description
Changed the description in Dword 0 for when it is a one. It now appears as follows:
Figure 21. Clock Mask and Load Shif t Timing
A8798-01
1 3 4 5 6 7 8 9
2
gpio<0>
gpio<2>
Shifted gpio<2>
msk_in
Primary Command Register
Dword Bit Name R/W Description
0 I/O space enable R/W
Controls the 21154’s response to I/O transactions on the primary
interface.
0 = The 21154 does not respond to I/O transactions initiated on
the primary bus.
1 = The 21154 response to I/O transactions initiated on the
primary bus is in the enabled state.
Reset value: 0.
21154 PCI-to-PCI Bridge Specification Update Intel Confidential33
Documentation Changes
17. Section 4.4.1, Serial Clock Mask Shift, Table 4
Table 4 has been changed as follows:
18. Section 4.4.1, Serial Clock Mask Shift, Figure 3
Figure 3 has been updated as follows:
Table 4. GPIO Serial Data Format
Bit Description s_clk_o Output
<15> Reserved Not applicable
<14> Reserved Not applicable
<13> 21154 s_clk input 9
<12> Device 8 8
<11> Device 7 7
<10> Device 6 6
<9> Device 5 5
<8> Device 4 4
<7:6> Slot 3 PRSNT#<1:0> or device 3 3
<5:4> Slot 2 PRSNT#<1:0> or device 2 2
<3:2> Slot 1 PRSNT#<1:0> or device 1 1
<1:0> S lot 0PRSNT#<1:0> or device 0 0
34Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Documentation Changes
19. Section 4.4.1, Serial Clo ck Mask Shift, Figure 4
Figure 4 now appears as follows:
20. Section 4.2, 21154 Output Clocks
This note has been added to the end of the section:
Note: Intel recommends that a 22K pull-up resistor be placed on s_clk to better insure proper
initialization on power-up.
Figure 3 Example of GPIO Clock Mask Implementation on the System Board
A7804-02
21154
74F166
CE#
CP
MR#
PE#
prsnto#<0>
prsnto#<1>
prsnto#<0>
prsnto#<1>
prsnto#<0>
prsnto#<1>
prsnto#<0>
prsnto#<1>
Ds
D7
msk_in
s_clk_<9>
gpio<0>
gpio<2>
v
SS
v
SS
D6
D5
D4
D3
D2
D1
D0
74F166
v
CC
v
CC
Q7
Q7
CE#
CP
MR#
PE#
D7
D6
D5
D4
D3
D2
D1
D0
Figure 4. Clock Mask Load and Shift Timing
A7803-01
gpio[0]
gpio[2]
msk_in Bit 15 Bit 14
21154 PCI-to-PCI Bridge Specification Update Intel Confidential35
Documentation Changes
21. Section 18.0, Table 51, 304-Point 2-Layer PBGA Package Dimensions
The maximum value for symbol aaa, dimension coplanarity has been changed from 0.15 mm to a
value of 0.2 mm.
22. Section 2.5, Secondary Bus Arbitration Signals, Table 8
This sentence is added to the end of the description for s_req_l <8:0>:
“When the secondary bus is set to operate at 66 MHz, s_req_l <8:4> is disabled.”
This sentence is added to the end of the description for s_gnt_l<8:0>:
“When the secondary bus is set to operate at 66 MHz, s_gnt_1 <8:4> i s disabled.”
23. Section 2.9, Miscel laneous Signals, Table 12
This sentence is added at the end of the description for S_m66ena:
“When the secondary bus is set to operate at 66 MHz, s_req_l <8:4> and s_gnt_1<8:4> are
disabled.”
24. Updated Version of PCI Local Bus Specification
All places in the 21154 Hardware Bridge Hard ware Implementat ion Applica tio n Note where the
PCI Local Bus Specification is mentioned was updated from version 2.1 to version 2.2.
25. Section 4.1, Updated s_clk and p_clk description
The first two paragraphs and the first bullet in Section 4.1 now appear as follows:
4.1 21154 Clocking Domains
The 21154 has two clocking domains: one for the primary PCI interface and one for the secondary
PCI interface. Each PCI interface has a separate clock input. The primary interf ace is controlled by
the primary clock input, p_clk, and the secondary interface and arbiter is controlled by the
secondary clock input, s_clk.
The edge relationship bet ween s_clk and p_clk is well defined . The relationship bet ween the p_clk
and s_clk inputs has the followin g restrictions:
•The 21154 operates at a maximum frequency of 66 MHz, and s_clk always operates at the
same frequency or half the frequency of p_cl k.
26. Section 4.2, Updated Clock Output s
The first bulleted item in Section 4.2 now appears as follows:
•All clock outputs operate at the same or half the frequency as p_clk.
27. Section 4.4.1, Added Note at End of Section.
The note added t o the end of Section 4.4.1 appears as follows:
Note: Refer to Errat a #7 previous ly in this docu ment for an expl anation of an add ed external bu ffe r on the
output of gpio <2> to use this feature at 66 MHz.
36Intel Co nfi den tia l 21154 PCI-to-PCI Bridge Specifica tion Up date
Documentation Changes
28. Section 4.5, Table 5 Product Part Numbers have been updated.
Table 5 now appears as follows:
Table 5. Low-S kew Clock Buffers
29. Updated Version of PCI Local Bus Specification
All references in the 21154 PCI-to-PCI Bridge documentation where the PCI Local Bus
Specification is mentioned were updated from version 2.2 to version 2.3.
Vendor Part Number (5V) Part Number (3.3V)
Texas Instruments CDC328A CDCV304
National Semiconductor CGS74B2525 CGS574CT2524
IDC 1DT74FCT805CT QS53805