In-Vehicle ECU Analog Signal Transmission Control
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Solution Overview
Problem
Existing in-vehicle electronic control units face challenges in efficiently transmitting digital conversion values from multiple analog signals and managing high communication control loads, leading to potential delays and wasted transmission in abnormality determination.
Innovation Solution
An in-vehicle electronic control unit design featuring a first control circuit with periodic transmission and AD conversion permission means, and a second control circuit with periodic reporting and AD conversion timing specifying means, allowing for synchronized AD conversion and prioritized reporting to alleviate control load and ensure up-to-date data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AD conversion is carried out at high frequency to obtain up-to-date digital information, then measurement precision is improved, but control load increases
Solution Approach 1:
The patent divides the control functions into two separate control circuit portions: the first control circuit portion handles communication control and generates AD conversion start instructions, while the second control circuit portion executes AD conversion and data transmission. This segmentation distributes the control load, allowing high-frequency AD conversion without overburdening a single controller.
Solution Approach 2:
The first control circuit portion acts as an intermediary that generates AD conversion start instructions based on communication timing, which are then sent to the second control circuit portion. This intermediary role coordinates the timing between communication cycles and AD conversion operations, enabling synchronized high-frequency conversion without direct burden on the second controller.
2Productivity
If multiple channels are converted simultaneously to transmit many digital values, then productivity is improved, but control load increases
Solution Approach 1:
The system uses periodic communication cycles where the first control circuit portion generates AD conversion start instructions at regular intervals synchronized with communication timing. This periodic action enables multiple channels to be converted in sequence across different cycles, achieving high productivity without requiring simultaneous conversion that would overwhelm the control circuit.
Solution Approach 2:
The first control circuit portion preliminarily determines the timing and generates AD conversion start instructions before the actual conversion occurs. By pre-coordinating the conversion timing with communication cycles, the system prepares the data transmission schedule in advance, allowing efficient multi-channel conversion without last-minute control complexity.
3Reliability
If abnormality determination is performed after AD conversion completion, then reliability is improved, but loss of time occurs
Solution Approach 1:
The first control circuit portion performs preliminary timing coordination by generating AD conversion start instructions synchronized with communication cycles. This preliminary timing setup allows the second control circuit portion to complete conversion and perform abnormality determination immediately when data becomes available, reducing detection delay while maintaining reliability through the synchronized timing framework.
Data Source
AI summary
A first control circuit portion carries out input/output control in cooperation with a microprocessor, a program memory, and a RAM memory. A second control circuit portion is in cooperation with the communication control circuit portion and the data memory to carry out serial communication with the first control circuit portion. A switch signal input to the second control circuit portion is stored in a first report packet, a digital conversion value for an analog signal input is stored in a second report packet, and the first and second packets are alternately periodically transmitted to the first control circuit portion. A multi-channel AD converter included in an analog signal input circuit starts to carry out AD conversion a prescribed time period after a first report packet is transmitted and finishes conversion before a second report packet is transmitted, so that up-to-date AD conversion data is transmitted.