Data Converter Diagnostic Bit for Stale Output Detection
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Solution Overview
Problem
Data converters using serial interfaces often fail to provide adequate information about their operational status, leading to potential safety issues in sensitive applications as they can continue to output old data even after malfunctioning, with external software solutions adding cost and complexity.
Innovation Solution
Incorporating a data conversion diagnostic bit that toggles upon completion of each data conversion cycle and reading of the data, allowing a host processor to monitor the bit's state for functionality, which can be embedded in the digital output data field or output on a separate pin, indicating whether new data is being generated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a serial data interface is used to read data from data registers, then the data converter can communicate with external devices, but the data converter cannot provide information about its operational status and may continue outputting old data after malfunctioning
Solution Approach 1:
The data output is segmented into two parts: the actual conversion data and a separate diagnostic bit. This segmentation allows the diagnostic bit to independently indicate operational status without affecting the main data function, resolving the contradiction by providing status information while maintaining data communication through the same serial interface.
Solution Approach 2:
A diagnostic bit acts as an intermediary element within the serial data interface. This intermediary provides operational status information without requiring a separate communication channel, thus resolving the information loss problem while maintaining the simplicity of the existing interface.
2Reliability
If external software and components are used to detect data converter malfunction, then the reliability can be improved, but the cost and complexity of the system increase
Solution Approach 1:
The data converter performs self-diagnosis by internally generating a diagnostic bit that indicates its operational status. This self-service approach eliminates the need for external software or components to detect malfunctions, resolving the contradiction by improving reliability through built-in functionality without increasing system complexity.
Solution Approach 2:
The serial data interface is given multi-functionality by incorporating both data output and diagnostic status indication through the diagnostic bit. This universal approach allows a single interface to serve multiple purposes, resolving the contradiction by providing fault detection capability without adding separate components or increasing complexity.
3Device complexity
If the diagnostic bit is embedded in the digital output data field, then no additional pins are required, but the data field must be modified
Solution Approach 1:
The digital output data field is segmented to include a diagnostic bit alongside the conversion data. This segmentation allows the diagnostic information to be embedded within the existing data structure without requiring additional physical pins, resolving the contradiction by maintaining simple pin configuration while accepting minor data field modifications.
Data Source
AI summary
A data converter (10) for digitizing an analog input signal and providing digital output data at one or more conversion cycles includes a logic circuit (28) for generating a data conversion diagnostic bit (38) having first and second logical states. The data conversion diagnostic bit toggles from one logical state to the other logical state when a conversion cycle is completed and when the digital output data from the previous conversion cycle has been read. The data conversion diagnostic bit remains at the same logical state when no conversion cycle has been completed or when no reading of the digital output data has been carried out.