DSI Sensor Addressing Voltage Control
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Solution Overview
Problem
The existing DSI protocol's Discovery Mode does not operate reliably in a daisy-chain configuration for sensor units in the Power Function Class mode due to high voltage drops and power losses, leading to incorrect address assignment in longer chains.
Innovation Solution
A method that alternates between communication, energy supply, and address assignment phases, using a higher address assignment voltage to detect current through test resistors, and incrementing addresses sequentially until all sensor units are addressed, with the option to vary the address assignment voltage and disconnect/reconnect test loads in stages to avoid overloading the central unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the DSI protocol's Discovery Mode is used for address assignment in a daisy-chain configuration, then the address assignment process can be automated, but high voltage drops and power losses occur in longer chains leading to incorrect address assignment
Solution Approach 1:
The patent applies parameter changes by switching between different voltage levels (3.3V for communication, 5V for address assignment) depending on the operational phase. During address assignment in longer chains, the voltage is increased to 5V to compensate for voltage drops and ensure reliable detection, while during normal communication the lower 3.3V is used to minimize power consumption.
Solution Approach 2:
The system dynamically adjusts the bus voltage based on the operational phase and chain length. The control unit detects whether the chain is short or long and switches between voltage levels accordingly, making the system adaptive to different configurations rather than using a fixed voltage level.
2Reliability
If a higher voltage is used during address assignment to compensate for voltage drops, then address detection reliability improves, but power consumption and risk of overloading the central unit increases
Solution Approach 1:
The patent implements periodic action by alternating between communication phases (using 3.3V) and address assignment phases (using 5V). The higher voltage is applied only periodically during address assignment when needed, rather than continuously, thus maintaining reliability while limiting overall power consumption.
Solution Approach 2:
The operational sequence is segmented into distinct phases: communication phases using lower voltage and address assignment phases using higher voltage. This segmentation allows the system to optimize power consumption by using high voltage only when necessary for address assignment, rather than continuously.
3Measurement precision
If test loads are connected in all sensor units during address assignment, then current detection through test resistors becomes possible, but the central unit may be overloaded in longer chains
Solution Approach 1:
The patent applies partial action by connecting test loads in only those sensor units that are actually needed for address assignment, rather than in all units. The control unit selectively activates test loads based on the detected chain configuration, using just enough action to achieve reliable address detection without excessive power consumption or overloading the central unit.
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
Ensures a robust and reliable address assignment for sensor units in a Power Function Class mode, preventing high power losses and ensuring accurate address detection even in longer chains, thereby improving the reliability of the address assignment process.
Implementation Method 1
the sensor units each have a test resistor connected in series with the two-wire bus cable... detecting the current flowing through each of the test resistors
Data Source
AI summary
The invention relates to a method for operating a sensor arrangement (2) in a motor vehicle (1) on the basis of a DSI protocol in a Power Function Class mode, wherein the sensor arrangement (2) has a central unit (3) and a multiplicity of sensor units (S1, S2, . . . , SN), the central unit and the sensor units are connected to one another in series by means of a bus cable (4), the sensor units each have a test resistor (RS1, RS2, . . . , RN) connected in series with the bus cable, an electrical test load (L1, L2, . . . , LN) that can be connected to the bus cable, and an address counter (A1, A2, . . . , AN), having the following steps: transferring information between the central unit (Z) and the sensor units by means of a predetermined lower voltage (VLOW-PWR) and a predetermined upper voltage (VHIGH-PWR) as the respective bus voltage (UBus) in communication phases, supplying the sensor units with electrical energy by means of the central unit in energy supply phases in which an idle voltage (VIDLE) is applied as the bus voltage, which is at least 1 V greater than the upper voltage, assigning a respective address to the individual sensor units in a previous address assignment phase by means of an address assignment voltage as the bus voltage, which is at least 1 V greater than the upper voltage.