Telematics Inter-Processor Communication via JTAG
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Solution Overview
Problem
In telematics systems, mismatched baud rates due to incompatible clock division, clock drift, or noise in UART communications can negatively impact high-speed serial inter-processor communications, disrupting normal operation during debugging or firmware upgrading.
Innovation Solution
A telematics system with a mobile processor and an applications processor communicating through multiple channels, utilizing an ARM core, EmbeddedICE macrocell, and TAP controller, which employs a debug communications data register and control register to manage data transfer via JTAG architecture, allowing for synchronous serial communication without disrupting normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If UART is used for high-speed serial inter-processor communications, then communication speed is improved, but communication reliability deteriorates due to mismatched baud rates from incompatible clock division, clock drift, or noise
Solution Approach 1:
The JTAG debugging bus is made multi-functional by enabling it to serve both debugging purposes during development and high-speed serial communication during normal operation. The same physical communication channels and protocol infrastructure are reused for both functions, eliminating the need for separate dedicated communication hardware while achieving reliable high-speed data transfer between processors.
2Reliability
If separate communication channels are added for debugging and firmware upgrading, then communication reliability is improved, but device complexity increases
Solution Approach 1:
The JTAG debugging bus serves multiple functions including debugging, high-speed serial communication, and firmware upgrading. By making the debugging infrastructure multi-functional, the patent avoids adding separate communication channels while maintaining reliable communication capabilities across all operational phases.
Solution Approach 2:
The patent merges the debugging communication function with the normal operational communication function by using the same JTAG bus infrastructure. This consolidation combines previously separate functions into a unified system, reducing overall device complexity while maintaining all necessary communication capabilities.
3Device complexity
If JTAG debugging bus is used for normal operation communication, then device complexity is reduced, but communication speed may deteriorate due to debugging protocol overhead
Solution Approach 1:
The communication protocol is segmented into distinct operational modes (debugging mode and normal operation mode) that can be independently optimized. During normal operation, the protocol operates in a streamlined mode that eliminates debugging-specific overhead while maintaining the underlying JTAG infrastructure, thus achieving high speed without the penalties of debugging protocol complexity.
Data Source
AI summary
A telematics system and method is provided, wherein the telematics system includes a processor having a core, a cell in communication with the core, and an applications processor in communication with the mobile processor. The system further includes at least one communication channel in communication between the mobile processor and the applications processor, wherein the mobile processor and the applications processor communicate data over the at least one communication channel during normal operation of a telematics system, and the mobile processor and applications processor communicate data over the at least one communication channel when the telematics system is at least one of being developed and manufactured.