RTC Drift Correction Using System Clock Indexing
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Solution Overview
Problem
Conventional real-time clock (RTC) devices face inaccuracies due to frequency drift caused by temperature and manufacturing errors, leading to increased device costs and reduced usable space with existing correction methods.
Innovation Solution
A method and apparatus for a portable device that uses a reference clock and processing module to record and calculate indexes from a reference clock, allowing for accurate time value correction by utilizing a system clock to adjust the RTC, thereby reducing drift errors and maintaining accurate timekeeping without additional storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a correction register is added to store correction values for RTC, then timekeeping accuracy is improved, but device cost increases and usable space decreases
Solution Approach 1:
The system uses the existing system clock to automatically calculate and apply correction values to the RTC without requiring external correction registers or additional storage elements. The RTC system serves itself by utilizing the system clock as both a reference and a correction source, eliminating the need for separate correction storage components.
Solution Approach 2:
The system clock serves multiple functions: it acts as both the primary time reference for system operations and the correction reference for the RTC. By making the system clock multi-functional, the patent eliminates the need for separate correction registers, thereby reducing device complexity and preserving usable space while maintaining timekeeping accuracy.
2Device complexity
If the crystal frequency is used directly for RTC, then device simplicity is maintained, but timekeeping accuracy deteriorates due to frequency drift
Solution Approach 1:
The system continuously monitors the system clock and uses it to calculate correction values that are applied to the RTC. This feedback mechanism compensates for crystal frequency drift by dynamically adjusting the RTC based on the more stable system clock, thereby maintaining timekeeping accuracy without adding complex correction hardware.
Solution Approach 2:
The patent changes the operational parameters of the RTC by introducing dynamic correction values derived from the system clock. Instead of relying on the fixed crystal frequency, the RTC parameters are continuously adjusted based on the system clock's performance, compensating for frequency drift while maintaining device simplicity.
Data Source
AI summary
A method for a portable device is disclosed. A reference clock is provided. A first time value and a first index are recording at a first time point. A second index is recorded at a second time point. The first time point and the second time point are counted according to the reference clock. The first index and the second index are calculated. A second time value is set according to the calculating result.