HVAC Controller Multiplexed Input Signal Detection
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Solution Overview
Problem
HVAC controllers face challenges in efficiently detecting alternating current (AC) input signals, as scanning these signals consumes significant bandwidth and requires multiple physical pins, increasing cost and complexity.
Innovation Solution
The implementation of a multiplexed input signal detection system that converts AC signals into square wave signals, allowing a single interrupt pin to support multiple signals through a signal conditioner, multiplexer, and sample analyzer, reducing the need for extensive scanning and pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AC input signals are scanned multiple times to determine binary state, then measurement accuracy is improved, but bandwidth consumption and computational load increase
Solution Approach 1:
The patent applies preliminary action by converting AC input signals to square wave signals before scanning. The signal conditioner converts AC signals to square waves with clear high/low states, enabling single-scan binary state determination without requiring multiple scans. This preliminary conversion resolves the contradiction by preparing the signal in advance in a form that can be accurately measured with minimal bandwidth consumption.
2Measurement precision
If multiple physical pins are used to detect multiple input signals, then measurement precision is improved, but device complexity and hardware cost increase
Solution Approach 1:
The patent applies merging by combining multiple input signal detection functions into a single physical pin through multiplexing. The multiplexer sequentially connects different input signals to one pin, allowing multiple signals to share a single detection channel. This resolves the contradiction by reducing the number of physical pins while maintaining accurate detection of all input signals through time-division multiplexing.
Solution Approach 2:
The patent applies universality by making a single physical pin capable of detecting multiple different input signals through the multiplexer. The same pin serves multiple functions by sequentially receiving different signals, eliminating the need for dedicated pins for each input. This multi-functionality approach resolves the contradiction between detection accuracy and hardware complexity.
3Device complexity
If AC signals are directly scanned without conversion, then device complexity is reduced, but measurement precision and reliability decrease
Solution Approach 1:
The patent applies parameter changes by transforming the AC signal parameters (frequency, amplitude) into square wave parameters (digital high/low states). The signal conditioner changes the signal form from analog AC to digital square wave, making it suitable for direct binary state determination. This parameter transformation resolves the contradiction by improving measurement precision through appropriate signal conditioning while keeping the overall device complexity manageable.
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 approach reduces computational load, power consumption, and hardware costs by enabling efficient detection of multiple input signals using fewer pins and minimizing scanning, while maintaining accurate binary state determination.
Implementation Method 1
a signal conditioner configured to convert received alternating current (AC) input signals into corresponding square wave signals of a digital logic voltage
Data Source
AI summary
A heating, ventilation and air conditioning (HVAC) controller, a method of detecting multiplexed input signals and an HVAC system employing the controller or the method. In one embodiment, the HVAC controller includes: (1) a signal conditioner configured to convert received alternating current (AC) input signals into corresponding square wave signals of a digital logic voltage, (2) a multiplexer coupled to the signal conditioner and configured to select one of the square wave signals and (3) a sample analyzer coupled to the multiplexer and configured to evaluate multiple samples of the selected one of the square wave signals to derive a binary state.