SENT Sensor IC with Embedded CRC for ASIL-D Diagnostics
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Solution Overview
Problem
Sensor integrated circuits (ICs) face challenges in achieving high diagnostic coverage and data integrity, particularly in safety-critical applications like automotive systems, where stringent safety integrity levels (ASIL) require robust redundancy and error detection mechanisms to ensure reliable operation.
Innovation Solution
The integration of a single monolithic integrated circuit on a semiconductor die with redundant Single Edge Nibble Transmission (SENT) outputs, including a cyclic redundancy check (CRC) and frame counting, to generate SENT frames that conform to ISO 26262 standards, ensuring high data integrity and diagnostic coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant sensing elements or technologies are used to achieve high diagnostic coverage and data integrity, then reliability improves, but device complexity increases
Solution Approach 1:
The patent combines multiple sensing elements (first and second sensing elements) and their processing circuits into a single integrated sensor IC package. This merging approach achieves the reliability benefits of redundant sensing while avoiding the complexity of managing separate discrete components, as the redundant elements are co-integrated and managed by a single processor within the same device.
Solution Approach 2:
The sensor IC is designed with a universal processor that can process signals from multiple different sensing elements using different sensing technologies (e.g., Hall elements or magnetoresistive elements). This multi-functional processor handles both redundant sensing channels and generates SENT output signals, reducing the need for separate dedicated processing circuits for each sensing element.
2Reliability
If homogeneous redundancy with two sensor ICs is used to achieve ASIL-D rating, then reliability improves, but loss of substance increases
Solution Approach 1:
The patent merges the functionality of two separate sensor ICs into a single integrated device. The sensor IC contains both sensing elements and their associated processing circuits in one package, eliminating the need for two separate ICs while maintaining the redundant sensing capability required for ASIL-D rating. This reduces material usage and device count.
3Measurement precision
If SENT protocol with additional diagnostic bits is used to achieve high diagnostic coverage, then measurement precision improves, but device complexity increases
Solution Approach 1:
The processor within the sensor IC preliminarily processes the sensing element signals by generating SENT protocol output signals with embedded diagnostic information before external transmission. The diagnostic bits are pre-formed and integrated into the SENT frame structure, allowing comprehensive diagnostic coverage to be achieved through software/firmware logic rather than additional hardware complexity.
Data Source
AI summary
A sensor includes a sensing element to produce a sensing element signal and a processor responsive to the sensing element signal to generate a sensor output signal comprising a Single Edge Nibble Transmission (SENT) frame. The SENT frame includes a Status and Communication (SCN) nibble comprising a bit 0 and a bit 1 that represent a status of at least one internal diagnostic indicator and a plurality of data nibbles. At least one of the plurality of data nibbles includes a cyclic redundancy check (CRC), the CRC being an encoding of the bit 0 and the bit 1 of the SCN nibble and the plurality of data nibbles and at least one of the plurality of data nibbles includes a count that indicates a new frame, the CRC being at least a five bit value.