Vehicle Communication Network Data Framing for CPU Load Reduction
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Solution Overview
Problem
Existing communication methods in vehicle networks, particularly when using SPI protocols, face challenges such as high CPU load and potential delays due to the need for a significant number of monitoring ports and complex CPU operations for heartbeat monitoring.
Innovation Solution
A communication method that frames data sent between master and slave data processing units using a start bit and a stop bit, allowing for interconnectivity between devices using asynchronous communication protocols like UART, thereby reducing the number of wires and pins required and alleviating CPU load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SPI protocol is used for heartbeat monitoring between master and slave data processing units, then reliable data transmission is achieved, but the number of monitoring ports required increases significantly and CPU load increases
Solution Approach 1:
The patent combines the data transmission function and heartbeat monitoring function into a single communication channel. The slave data processing unit transmits both data packets and heartbeat signals through the same SPI interface, eliminating the need for separate monitoring ports. The master data processing unit identifies heartbeat packets by their specific format (containing device ID and status information), thereby reducing port requirements while maintaining monitoring reliability.
Solution Approach 2:
The communication interface is designed to serve multiple functions simultaneously. The same SPI port used for data transmission also handles heartbeat monitoring, and the same port can be used for both sending and receiving monitoring signals. This multi-functional design reduces the total number of ports required at both master and slave units.
2Reliability
If multiple monitoring ports are used for heartbeat monitoring via SPI protocol, then monitoring reliability is improved, but CPU load increases and processing delays occur
Solution Approach 1:
The patent extracts the heartbeat monitoring function from the general data processing workflow. Heartbeat packets are identified by their distinctive format (containing specific device ID and status fields), allowing the system to separate monitoring tasks from data processing tasks. This extraction enables optimized handling where heartbeat packets can be quickly recognized and processed independently.
Solution Approach 2:
The slave data processing unit automatically generates and transmits heartbeat packets without requiring active intervention from the master unit. The slave unit self-monitors its own status and proactively reports to the master, reducing the CPU load on the master unit that would otherwise be required to actively query each slave's status.
3Reliability
If SPI protocol with multiple ports is used for communication, then communication reliability is improved, but the number of physical pins required increases
Solution Approach 1:
The patent merges multiple communication functions into a single SPI interface. Both data transmission and heartbeat monitoring share the same MOSI, MISO, SCK, and SS pins. The slave select line is reused for both data communication and monitoring purposes, significantly reducing the total number of physical pins required compared to having separate dedicated ports for each function.
4Measurement precision
If dedicated monitoring ports are allocated for each slave unit, then monitoring precision is improved, but device complexity and pin count increase
Solution Approach 1:
The patent introduces a standardized heartbeat packet format as an intermediary mechanism. Instead of requiring dedicated ports for each slave, the system uses a universally recognized packet structure that contains device ID and status information. The master unit identifies and processes heartbeat packets from different slaves through this standardized format, maintaining monitoring precision while simplifying the communication interface.
Data Source
AI summary
A communication method for a communication network of a vehicle includes a master data processing unit and a slave data processing unit connected to the master data processing unit via a synchronous serial communication interface. The slave data processing unit is connected to the master data processing unit via a slave select line for indicating that data is being sent from the master data processing unit to the slave data processing unit. The data sent from the master data processing unit to the slave data processing unit and/or from the slave data processing unit to the master data processing unit is framed by a start bit as a first bit and a stop bit as a last bit of the sent data.