CCI Communication Protocol for CRC-Safe Register Writes
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Solution Overview
Problem
The Camera Control Interface (CCI) used in automated driving systems lacks a transmission error detection function, leading to potential misinterpretation of cyclic redundancy check (CRC) codes as register write data, causing malfunctions or errors in image sensors.
Innovation Solution
A communication device and system that includes a protocol with a first operation and a second operation, where the second operation contains identification information, a write-instructing information, and a CRC code to detect errors, along with a counter and CRC code generation unit to ensure accurate data transmission and error detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CRC code is attached to the operation transmitted via CCI to enable error detection, then error detection capability is improved, but the operation is misrecognized as register write data causing malfunction
Solution Approach 1:
The protocol is segmented into two distinct operation types: first operations for normal register writes and second operations for CRC verification. This segmentation allows the receiving device to differentiate between data writing operations and error detection operations, preventing misrecognition while maintaining error detection capability.
Solution Approach 2:
A counter is introduced as an intermediary mechanism to track the number of first operations. The counter value is transmitted in the second operation along with the CRC code, enabling the receiving device to verify both data integrity and operation count without misinterpreting the CRC data as register write content.
2Reliability
If the CCI protocol is modified to include error detection functions, then transmission reliability is improved, but compatibility with existing CCI operations deteriorates
Solution Approach 1:
The protocol design provides universality by supporting multiple operation types within the same CCI framework. First operations maintain backward compatibility for normal register writes, while second operations enable CRC verification. The receiving device can handle both operation types using the same interface, ensuring compatibility while adding error detection functionality.
Solution Approach 2:
The protocol introduces parameter changes by adding a second operation type with specific characteristics (including CRC code and counter value) while preserving the original first operation format. This allows the system to transition from basic CCI to enhanced CCI with error detection without fundamentally changing the existing operation structure.
Data Source
AI summary
Communication devices and systems are disclosed. In one example, a communication device is configured to communicate with a communication partner device in accordance with a protocol including a first operation and a second operation. The first operation includes identification information of the communication partner device, write-instructing information, identification information of a first storage unit of the communication partner device, and data to be written in the first storage unit. The second operation follows the first operation and includes identification information of the communication partner device, write-instructing information, identification information of a second storage unit of the communication partner device, information indicating a number of the protocols, and a cyclic redundancy check (CRC) code used to detect an error in the protocol. The second storage unit is configured to store the CRC code and the information indicating the number of the protocols.