Microcontroller Real-Time Clock Using Digital Comparator and ADC
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Solution Overview
Problem
Real-time clocks (RTCs) implemented with analog comparators in pierce oscillator configurations are costly and not suitable for driving microelectromechanical systems (MEMS) due to differing electrical characteristics, and external RTC modules for microcontrollers are also cost burdensome.
Innovation Solution
A microcontroller-based real-time clock system that generates a real-time clock signal by providing an excitation signal to a crystal in a pierce oscillator configuration, converting the signal to digital output, comparing it to thresholds, and driving the crystal to maintain oscillation, thereby eliminating the need for external components like inverters and shapers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog comparators are used in pierce oscillator configuration for RTC implementation, then the clock signal generation is achieved, but the cost increases and compatibility with MEMS is reduced
Solution Approach 1:
The patent extracts the analog comparator function from the traditional pierce oscillator configuration and replaces it with a digital comparator implemented within the microcontroller. This removes the need for external analog components while maintaining the clock generation function, thereby reducing cost and improving manufacturability.
Solution Approach 2:
The patent substitutes the mechanical/electrical analog comparator system with a digital processing system. The microcontroller's digital logic and ADC circuitry replace the analog comparator, enabling the system to function with digital signal processing instead of analog circuitry, which reduces component count and cost.
2Adaptability or versatility
If external RTC modules are provided for microcontrollers, then real-time clock functionality is achieved, but the cost increases
Solution Approach 1:
The patent merges the real-time clock functionality directly into the microcontroller unit. The crystal oscillator, ADC circuit, and digital comparator are integrated within the microcontroller, eliminating the need for separate external RTC modules. This consolidation reduces component count, board space, and overall system cost while maintaining full real-time clock functionality.
Solution Approach 2:
The microcontroller is designed to perform multiple functions including real-time clock operation, ADC conversion, and digital signal processing. By making the microcontroller universal and multi-functional, the system eliminates dedicated external RTC modules, thereby reducing cost while maintaining adaptability and versatility.
3Ease of operation
If inverter and shaper components are used in pierce oscillator configuration, then the oscillation signal is conditioned, but the device complexity increases
Solution Approach 1:
The patent extracts the signal conditioning function from external inverter and shaper components and integrates it into the microcontroller's digital logic. The ADC circuit and digital comparator perform the necessary signal conditioning internally, eliminating external components and reducing device complexity.
Solution Approach 2:
The patent merges the functions of the inverter, shaper, and comparator into a single integrated digital processing unit within the microcontroller. This consolidation of multiple discrete components into one integrated system reduces device complexity while maintaining the necessary signal conditioning capabilities.
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 solution reduces costs by integrating RTC functions within a microcontroller, enabling efficient generation of accurate real-time clock signals suitable for MEMS applications with improved energy efficiency and reduced power consumption.
Implementation Method 1
providing an excitation signal to a crystal in a pierce oscillator configuration
Implementation Method 2
a crystal in a pierce oscillation configuration
Data Source
AI summary
A device including at least one processor, and an analog-to-digital (ADC) circuit, wherein the at least one processor is configured to generate an excitation signal and provide the excitation signal to a crystal in a pierce oscillation configuration, wherein after providing the excitation signal, the ADC circuit is configured to obtain as input a signal output from the crystal and convert the signal to a digital output; the at least one processor is configured to compare the digital output of the ADC circuit to a plurality of thresholds and based on the comparisons is further configured to drive the crystal to cause the crystal to operate as a pierce oscillator and to generate a clock signal from at least of one of the comparisons.