Daisy Chain Priority Scheduling for Deterministic Data Transmission
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Solution Overview
Problem
Existing daisy chain communication systems face challenges in ensuring real-time data transmission and determinism while minimizing cabling and maintaining data bandwidth, particularly in applications like self-driving automobiles, where high priority data needs to be transmitted within a pre-configured delay.
Innovation Solution
Implementing a data channel topology with package scheduling that allows devices in a daisy chain configuration to only output packages with higher priority, ensuring that high-priority data is transmitted first, and using a single physical channel to maintain real-time behavior and determinism without increasing the number of wires or decreasing bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If priority-based package scheduling is implemented in daisy chain communication, then real-time data transmission and determinism are improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by introducing priority values as a new parameter to existing daisy chain communication packages. Each device compares priority values of outgoing packages against incoming packages and adjusts transmission decisions accordingly. This parameter addition enables real-time scheduling without requiring fundamental changes to the physical communication layer, thus improving reliability while limiting complexity increase to primarily logical/control aspects.
2Reliability
If priority-based package scheduling is implemented in daisy chain communication, then determinism is improved, but data bandwidth is reduced
Solution Approach 1:
The patent applies partial action by selectively blocking only those specific packages that violate priority ordering rules, rather than blocking all packages or implementing complete retransmission mechanisms. This partial blocking approach maintains determinism for high-priority data while allowing lower-priority data to pass through when appropriate, thereby preserving as much data bandwidth as possible while achieving the desired real-time behavior.
3Productivity
If multiple independent connections are used for daisy chain communication, then data bandwidth is improved, but cabling complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the data transmission function into discrete priority levels within a single communication channel. Instead of using multiple physical connections to achieve bandwidth, the system segments the data flow into priority-based streams that share the same physical medium. This allows high-priority data to be transmitted efficiently without requiring separate cabling for each data stream, thus maintaining bandwidth performance while reducing cabling complexity.
Data Source
AI summary
A device configured to receive a set of bits for a first package from a previous device of a plurality of devices connected in a daisy chain configuration, the set of bits for the first package including a first priority value and if the device does not have a second package for output to a destination device of the plurality of devices, output the set of bits for the first package to a subsequent device of the plurality of devices. When the device has the second package for output to the destination device of the plurality of devices, the device is configured to determine whether the second priority value is higher than the first priority value and if the second priority value is higher than the first priority value output a set of bits for the second package to the subsequent device of the plurality of devices.