IP Library Granted Patent US 8,127,190
Granted Patent B2
US 8,127,190 · App. 11/552,128 · Granted Feb 28, 2012

Sampling a device bus

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Quick Facts
Patent No.
US 8,127,190
App. No.
11/552,128
Granted
Feb 28, 2012
Kind
B2
Abstract

A method for preparing tapped data for analysis. The data on a bus is sampled and latched at a certain rate to produce raw data. The raw data is then decoded by a pod that is configured for the protocol of the bus in a system under test. The decoded data can then be presented to a protocol analyzer for analysis. The decoded data and the corresponding raw data may also be aligned and then presented to an analyzer for protocol analysis.

Claims (40)

1. A method for analyzing tapped data on a bus having a plurality of lines between a host and a device, the method comprising:

providing a tap board that taps the bus between the host and the device;

sampling the bus using the tap board to produce raw data;

decoding the raw data to produce decoded data;

aligning a portion of the decoded data with corresponding samples of the raw data;

sending a first ID from the tap board to a pod connected to the tap board indicative of what type of tap is attached;

selecting a protocol of the bus from multiple protocols for analysis based on the first ID; and

programming the pod to handle the selected protocol,

wherein the pod provides the aligned portion of the decoded data and raw data samples to a protocol analyzer for analysis.

2. The method of claim 1 , wherein providing the tap board that taps the bus further comprises providing a tap board that taps each line of the bus.

3. The method of claim 1 , further comprising one or more of:

generating a timing waveform from the decoded data;

generating a tree view from the decoded data; or

triggering based on the decoded data.

4. The method of claim 1 , further comprising:

sending a second ID from the pod to the analyzer such that the analyzer knows which pod is attached; and

selecting a type of analysis based on the second ID.

5. The method of claim 1 , further comprising providing a pass through bus with the tap board without retiming signals present on the bus between the host and the device.

6. The method of claim 1 , further comprising analyzing each line of the bus using the alignment of each sample of raw data to a corresponding bit.

7. A method for analyzing data in a system under test, the system including a host and a device, the method comprising:

connecting a tap to the system under test, wherein the tap provides a pass through bus having a plurality of lines between the host and the device;

connecting the tap with a pod that is connected with a protocol analyzer;

receiving an ID from the tap at the pod, wherein the protocol analyzer uses the ID to configure the pod for a protocol operating in the system under test;

repeatedly sampling the pass through bus based on a clock provided by the pod to produce a segment of raw data;

repeatedly sampling the bus by latching data on the rising and/or falling edge of the clock until a segment of data is obtained and represented by raw data, wherein each bit in the segment of data is sampled and latched more than once;

at the pod, decoding the segment of raw data into decoded data; and

at the pod, aligning the segment of raw data with the decoded data.

8. The method of claim 7 , wherein repeatedly sampling the pass through bus further comprises tapping lines of the bus without retiming the signals on the lines of the bus.

9. The method of claim 7 , further comprising one or more of:

generating a state listing from the decoded data; or

generating command decoding from the decoded data.

10. The method of claim 7 , further comprising visually presenting the segment of raw data aligned with the decoded data, such that each bit of the decoded data is associated with a plurality of samples of the segment of raw data.

11. The method of claim 10 , further comprising identifying a problem with a particular line of the pass through bus based on the alignment of the segment of raw data with the decoded data.

12. The method of claim 7 , wherein the segment of raw data corresponds to a byte of data.

13. The method of claim 7 , wherein repeatedly sampling the pass through bus further comprises sampling one bit on each line of the bus.

14. The method of claim 7 , further comprising preparing the decoded data for the protocol analyzer.

15. The method of claim 7 , further comprising receiving the segment of raw data from the tap as low voltage differential signals.

16. The method of claim 15 , further comprising adjusting internal voltages of an FPGA in the pod to accommodate the low voltage differential signals.

17. The method of claim 16 , further comprising translating signals generated by the FPGA into a form that is required by the protocol analyzer.

18. The method of claim 16 , further comprising translating LVTTL signals to LVDS signals.

Assignments (8)
RELEASE OF SECURITY INTEREST AT REEL/FRAME 73189/0873 Recorded May 28, 2026
From: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
To: INERTIAL LABS, INC.; VIAVI SOLUTIONS INC.; VIAVI SOLUTIONS LICENSING LLC
Reel/Frame 075642/0381 →
SECURITY INTEREST Recorded Nov 14, 2025
From: VIAVI SOLUTIONS INC.; VIAVI SOLUTIONS LICENSING LLC; INERTIAL LABS, INC.
To: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS AGENT
Reel/Frame 073571/0137 →
SECURITY AGREEMENT Recorded Oct 21, 2025
From: INERTIAL LABS, INC.; VIAVI SOLUTIONS INC.; VIAVI SOLUTIONS LICENSING LLC
To: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
Reel/Frame 073189/0873 →
TERMINATIONS OF SECURITY INTEREST AT REEL 052729, FRAME 0321 Recorded Jan 5, 2022
From: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
To: VIAVI SOLUTIONS INC.; RPC PHOTONICS, INC.
Reel/Frame 058666/0639 →
SECURITY INTEREST Recorded May 21, 2020
From: VIAVI SOLUTIONS INC.; 3Z TELECOM, INC.; ACTERNA LLC; ACTERNA WG INTERNATIONAL HOLDINGS LLC; VIAVI SOLUTIONS LLC; JDSU ACTERNA HOLDINGS LLC; OPTICAL COATING LABORATORY, LLC; RPC PHOTONICS, INC.; TTC INTERNATIONAL HOLDINGS, LLC
To: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
Reel/Frame 052729/0321 →
CHANGE OF NAME Recorded Nov 6, 2015
From: JDS UNIPHASE CORPORATION
To: VIAVI SOLUTIONS INC.
Reel/Frame 037057/0627 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Feb 2, 2011
From: FINISAR CORPORATION
To: JDS UNIPHASE CORPORATION
Reel/Frame 025730/0518 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Feb 23, 2007
From: LANNING, ERIC
To: FINISAR CORPORATION
Reel/Frame 018927/0808 →