Accessory Checksum Signaling for Serial Data Retransmission
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Solution Overview
Problem
In electronic devices with limited pins, the complexity of slave device configuration and data verification increases due to insufficient pins, making it difficult to handle checksum errors during serial communication, which complicates data retransmission and accuracy determination between master and slave devices.
Innovation Solution
An accessory with a processor and memory that calculates and manages checksums, allowing for error notification and retransmission requests through serial communication, simplifying the data verification process and ensuring data accuracy without relying on additional communication means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slave request is prepared for checksum error notification, then data verification accuracy is improved, but device complexity increases due to additional communication means
Solution Approach 1:
The patent combines the checksum error notification function with the existing serial communication protocol. Instead of adding a separate communication channel or slave request mechanism, the invention embeds error notification within the data transmission stream itself, using the same SDA and SCL pins for both data communication and error signaling, thereby avoiding additional hardware complexity while maintaining reliability
Solution Approach 2:
The serial communication interface is designed to serve multiple functions: data transmission, checksum verification, and error notification. The same communication pins and protocol infrastructure are used for both normal data exchange and error condition signaling, eliminating the need for dedicated error notification hardware and reducing overall device complexity
2Reliability
If additional communication means are added for error notification, then data retransmission capability is improved, but the number of pins required increases
Solution Approach 1:
The patent merges the error notification function into the existing two-wire serial communication interface. Error conditions are signaled by manipulating the data lines during the communication sequence, allowing retransmission requests to be conveyed using the same SDA and SCL pins already required for data transmission, thus avoiding any increase in pin count
Solution Approach 2:
The serial communication bus is designed to handle multiple tasks simultaneously: normal data transmission and error condition signaling. By encoding error notifications within the existing protocol framework, the system achieves full-duplex functionality (data and error signaling) on a single bidirectional bus, eliminating the need for additional dedicated error pins
3Measurement precision
If checksum verification is implemented, then data transmission accuracy is improved, but communication protocol complexity increases
Solution Approach 1:
The patent implements preliminary checksum calculation and verification within the serial communication flow. Checksum values are pre-calculated for transmitted data blocks and verified upon reception before proceeding to the next communication phase, allowing error detection to be integrated seamlessly into the existing communication control logic without requiring separate verification subsystems
Solution Approach 2:
The system employs feedback mechanisms where checksum verification results directly influence subsequent communication actions. When checksum errors are detected, the protocol automatically triggers retransmission sequences, creating a closed-loop error correction system that maintains data accuracy while keeping control logic manageable through standardized feedback responses
Data Source
AI summary
An accessory and an electronic device enabling retransmission of data from the electronic device to the accessory when a checksum error occurs in the accessory. An accessory controller of the accessory determines whether or not a checksum received from the camera and a first checksum calculated from data received from the camera match. In a case where the checksums match, the accessory controller calculates a second checksum, whereas in a case where the checksums do not match, the accessory controller calculates a third checksum. The accessory controller transmits the second checksum or the third checksum to the camera according to a result of the determination.