Single JTAG Controller for Mixed Full and Reduced Pin Devices

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Solution Overview

Problem

Existing technologies require substrates to have both full and reduced pin JTAG interfaces, which complicates test and debug operations.

Innovation Solution

A single JTAG controller is used to access both full and reduced pin JTAG devices on a substrate through a single interface, eliminating the need for separate full and reduced pin JTAG interfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If both full pin JTAG interface and reduced pin JTAG interface are provided on substrate, then both full pin JTAG devices and reduced pin JTAG devices can be accessed, but device complexity and resource requirements increase

Engineering Contradiction:

Improvecompatibility with both full pin and reduced pin JTAG devicesVSAvoidcomplexity of test and debug operations

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The single JTAG controller is designed to perform multiple functions by supporting both full pin JTAG interface operations and reduced pin JTAG interface operations. The controller can dynamically adapt its operation mode based on the connected device type, eliminating the need for separate dedicated controllers for each interface type while maintaining compatibility with both device categories.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the functionality of separate full pin JTAG controller and reduced pin JTAG controller into a single unified JTAG controller. This merging consolidates the control logic and interface management into one component, reducing the overall system complexity while preserving the ability to interface with both full pin and reduced pin JTAG devices through appropriate protocol selection.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If separate full pin JTAG interface and reduced pin JTAG interface are used, then both device types can be accessed, but the quantity of interface components increases

Engineering Contradiction:

Improveability to access different JTAG device typesVSAvoidnumber of interface components

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The single JTAG controller serves as a universal interface component that can communicate with both full pin JTAG devices and reduced pin JTAG devices. By implementing multiple communication protocols within one controller, the system reduces the total number of interface components from two separate controllers to one, while maintaining the ability to access diverse device types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The JTAG controller dynamically changes its operational parameters and communication protocol based on the detected device type. When a full pin JTAG device is detected, the controller activates the full pin protocol; when a reduced pin JTAG device is detected, it switches to the reduced pin protocol. This parameter adaptation allows one controller to replace what would traditionally require two separate controllers.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If a single interface is used for both full pin and reduced pin JTAG devices, then complexity is reduced, but compatibility requirements increase

Engineering Contradiction:

Improvesimplicity of test and debug operationsVSAvoidcompatibility with different JTAG interface types

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The JTAG controller implements dynamic protocol selection capability, automatically adapting its communication mode based on the connected device type. The controller can switch between full pin JTAG protocol and reduced pin JTAG protocol in real-time, making the interface behavior dynamic rather than static. This dynamic adaptation simplifies the overall system architecture while maintaining broad compatibility.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller changes its operational parameters including signal timing, pin configuration, and communication protocol based on the detected device type. By implementing parameter adaptation logic, the single interface can accommodate the different requirements of full pin and reduced pin JTAG devices without requiring separate dedicated interfaces, thus maintaining simplicity while ensuring compatibility.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250052811A1Interface to full and reduced pin JTAG devices

Publication Date: 2025.02.13 TEXAS INSTRUMENTS INC

AI summary

The disclosure describes a process and apparatus for accessing devices on a substrate. The substrate may include only full pin JTAG devices (504), only reduced pin JTAG devices (506), or a mixture of both full pin and reduced pin JTAG devices. The access is accomplished using a single interface (502) between the substrate (408) and a JTAG controller (404). The access interface may be a wired interface or a wireless interface and may be used for JTAG based device testing, debugging, programming, or other type of JTAG based operation.