HVAC Controller Multiplexed AC Input Signal Detection Using Single Pin
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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 signal conditioner to convert AC input signals into square wave signals, a multiplexer to select and analyze these signals, and a sample analyzer to derive binary states, allowing for multiplexed input signal detection and reducing the need for multiple pins and scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the controller scans AC input signals to determine binary states, then the input signals can be detected, but the bandwidth consumption increases and multiple physical pins are required
Solution Approach 1:
The patent combines multiple input signal detection functions into a single physical pin by implementing a multiplexer that time-division multiplexes multiple AC input signals through one shared pin, eliminating the need for separate pins for each input signal while maintaining detection capability
Solution Approach 2:
The controller pin is designed to serve multiple functions by detecting multiple different AC input signals sequentially through the multiplexer, allowing a single pin to replace what would traditionally require multiple dedicated pins
2Measurement precision
If the controller scans AC input signals to determine binary states, then the input signals can be detected, but the computational load and power consumption increase
Solution Approach 1:
The system uses periodic sampling of AC input signals through the multiplexer, where signals are sampled at specific intervals rather than continuously scanned, reducing the computational burden and power consumption while still accurately determining binary states
Solution Approach 2:
The multiplexer pre-processes and routes the appropriate AC input signal to the single pin before the controller reads it, eliminating the need for the controller to perform complex scanning operations and reducing its computational load and energy consumption
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.