SENT Sensor Selection via Pulse Counting
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Solution Overview
Problem
The existing methods for deterministic sensor selection using the SENT protocol are prone to misinterpretation due to poorly defined edge rates caused by external resistance and capacitance, leading to incorrect sensor selection.
Innovation Solution
A method utilizing a three-wire bus connection with a control unit that sends a selection signal with a predetermined number of pulses in succession, allowing for unambiguous sensor selection, where each sensor is associated with a unique number of pulses, and the pulse duration is irrelevant for selection, enabling reliable and rapid data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pulse duration is varied for sensor selection using SENT protocol, then sensor selection capability is achieved, but misinterpretation occurs due to poorly defined edge rates
Solution Approach 1:
The patent changes the selection criterion from pulse duration (which has poorly defined edge rates) to the number of pulses in a sequence. Each sensor is assigned a unique number of pulses (e.g., sensor 1 gets 1 pulse, sensor 2 gets 2 pulses), making the selection parameter discrete and unambiguous, thereby resolving the edge rate definition problem while maintaining reliable sensor selection.
2Device complexity
If multiple sensors are connected in parallel on a three-wire bus, then system complexity is reduced, but deterministic selection becomes unreliable
Solution Approach 1:
The patent segments the selection process into multiple discrete pulse events rather than relying on a single continuous pulse duration measurement. By using a sequence of pulses where each sensor responds to a specific number of pulses, the system maintains simple parallel connectivity while achieving reliable deterministic selection through temporal segmentation of the selection signal.
3Ease of operation
If pulse duration is used for sensor selection, then selection mechanism is simple, but selection reliability deteriorates due to external resistance and capacitance
Solution Approach 1:
The patent substitutes the continuous analog measurement of pulse duration (which is affected by external RC time constants) with a discrete digital counting mechanism. The control unit simply counts the number of pulses in the sequence rather than measuring the total duration, replacing a sensitive analog measurement system with a robust digital counting system that is immune to external electrical interference.
Data Source
AI summary
Method for a deterministic selection of a sensor from a plurality of sensors, having a control unit and multiple sensors connected to the control unit by means of a three-wire bus, wherein the sensors are connected parallel to one another at a three-wire bus by at least two lines and a protocol frame according to SENT specification is used between the control unit and the sensors for a data exchange, and within the protocol frame a specified sensor is selected from a plurality of sensors by means of a selection signal sent by the control unit, wherein each sensor is associated with an unambiguous number of pulses for the selection of the sensor, and the selection of the sensor is performed by means of the selection signal having a predetermined number of pulses occurring immediately in succession.