Bus Tap Sampling for Protocol Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Protocol analyzers face difficulties in analyzing SD, SDIO, MMC, and CE-ATA protocols due to physical device sizes, cost, voltage level mismatches, and impedance issues, particularly when dealing with electrical buses and unknown voltage levels.
Innovation Solution
A system and method for sampling data on a bus between a host and a device, using a tap connected to a pod that interfaces with a protocol analyzer, allowing for sampling without knowing the bus speed or operating voltage, with the pod decoding and aligning raw data to facilitate analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a protocol analyzer is directly connected to analyze bus data, then data capture capability is improved, but cost and complexity increase due to voltage level mismatches and impedance issues
Solution Approach 1:
The patent introduces a tap device as an intermediary component between the bus and the protocol analyzer. The tap samples the bus signals and presents them to the analyzer through a controlled interface, isolating the analyzer from direct exposure to voltage level mismatches and impedance issues. This mediator approach allows accurate data capture without requiring the analyzer to directly tolerate the complex electrical characteristics of the bus.
Solution Approach 2:
The tap creates a copy of the bus signals by sampling them at a rate higher than the bus clock rate. This copied data is then presented to the protocol analyzer, which analyzes the sampled data without being directly exposed to the original bus electrical conditions. The copying process enables the analyzer to work with simplified signal representations that are easier to process.
2Measurement precision
If the bus is sampled at a higher clock rate, then data sampling accuracy is improved, but device complexity increases due to unknown bus speed and voltage levels
Solution Approach 1:
The tap is designed with a fixed, high sampling rate that is predetermined to be higher than the maximum expected bus clock rate. This preliminary configuration of the sampling rate eliminates the need for dynamic adjustment or complex detection of bus speed during operation. The tap always samples at the correct high rate regardless of the actual bus operating conditions.
Solution Approach 2:
The tap device automatically adapts to unknown bus voltage levels and speeds by using a fixed high sampling rate that works for all supported protocols. The system serves itself by using the tap's built-in sampling capability to handle various bus conditions without requiring external configuration or complex detection mechanisms.
3Adaptability or versatility
If protocol analyzers are repeatedly connected and disconnected, then adaptability to different devices is improved, but cost increases due to connector durability limits
Solution Approach 1:
The system is segmented into three independent parts: the tap device, the protocol analyzer, and the pod interface. The tap can be detached and reattached to different devices without affecting the analyzer or pod. This segmentation isolates the wear and tear to only the tap connector, which is designed to be replaceable, while protecting the more expensive and sensitive analyzer connectors.
Solution Approach 2:
The tap device is designed as a disposable or easily replaceable component with a limited-duty-cycle connector. Rather than protecting the expensive protocol analyzer connectors from wear, the design accepts that the tap connector will degrade and can be simply replaced. This approach is economically viable because the tap is a lower-cost component compared to the analyzer.
Data Source
AI summary
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.