LIN Communication Address Assignment Current Management
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Solution Overview
Problem
In conventional LIN-based communication systems, the address assignment process for multiple slaves results in a high current draw on the master node, which is undesirable, especially with a large number of slaves, and reduces the detectability of identification currents.
Innovation Solution
The communication system rearranges the constant current supplies and sense resistors in the slaves, with the constant current supplies disposed between the bus and ground potential, and uses a comparator and amplifier to detect identification currents, allowing for reduced identification current outputs and efficient address assignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple slaves are connected to the master node in a LIN-based communication system, then the system can support more devices, but the current draw on the master node increases significantly
Solution Approach 1:
The patent segments the current measurement function by placing sense resistors in each slave node rather than requiring the master to handle all current measurements. This distributes the measurement burden and allows independent current control for each slave, reducing the master's current draw requirements.
Solution Approach 2:
The patent changes the parameter of identification current magnitude by making it variable and adaptive. The master node adjusts the identification current based on system conditions, and the system supports reduced identification current outputs that maintain detectability while reducing overall current consumption.
2Quantity of substance
If the number of slaves increases, then the system capacity improves, but the detectability of identification currents decreases
Solution Approach 1:
The patent introduces sense resistors as intermediary components in each slave node to facilitate precise current measurement. These sense resistors convert identification currents into measurable voltage drops, enabling reliable detection even when currents are reduced, thus maintaining measurement precision despite increased system complexity.
Solution Approach 2:
The patent replaces direct current measurement with voltage measurement across sense resistors. This substitution allows for more precise and reliable detection of identification currents, as voltage measurements are easier to amplify and process with high precision compared to direct current measurements.
3Adaptability or versatility
If conventional address assignment is used with multiple slaves, then all slaves can be addressed, but the current demand on the master node increases
Solution Approach 1:
The patent implements self-service by enabling each slave node to independently generate and control its own identification currents through local constant current supplies and switches. This eliminates the need for the master node to source high currents for all slaves simultaneously, reducing the master's current demand while maintaining full address assignment capability.
Solution Approach 2:
The patent employs periodic action by sequentially activating identification currents in different slave nodes during the address assignment process. Instead of all slaves drawing current simultaneously, the system cycles through slaves in sequence, reducing the peak current demand on the master node while still enabling complete address assignment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration suppresses the maximum current drawn from the master node regardless of the number of slaves and improves the detectability of identification currents, enabling effective address assignment without increasing current demand.
Implementation Method 1
a constant current supply (CI7 to CI1) disposed between the bus and an application end of a ground potential or between an application end of a power supply voltage and the bus
Implementation Method 2
uses a comparator and amplifier to detect identification currents
Implementation Method 3
an identification current detection unit (DI7 to DI1) disposed, in the bus, on a post-stage side of a node (Nc7 to Nc1) at which the constant current supply is connected to the bus
Data Source
AI summary
A communication system is configured to be capable of executing an address assignment process including: a first process for detecting presence/absence of an identification current input by means of an identification current detection unit when a constant current supply has generated an identification current output with a switch and a second transistor in an off state; and a second process for repeatedly executing the first process while, with respect to a slave among the slaves that has had the identification current input detected therein, stopping generation of the identification current output thereafter, and assigning an address to a single slave among the slaves that has not had the identification current input detected therein, and is also configured to be capable of executing the address assignment process while excluding a slave among the slaves that has had the address assigned thereto.