Microcomputer A/D Port Signal Level Shifting for Pin Reduction
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Solution Overview
Problem
Existing techniques for signal determination and temperature measurement using microcomputers often require more pins than necessary, leading to increased costs and potential errors due to unused terminals, and fail to efficiently handle mixed analogue and digital signals at a single port.
Innovation Solution
A temperature determination apparatus with a signal detection section, a thermistor connected to an A/D input port, and a level shift section that adjusts signal levels to distinct ranges based on priority signals, allowing for simultaneous processing of analogue and digital signals at a single port, thereby reducing the number of pins required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a microcomputer with more pins is used to handle all signals, then signal processing capability is improved, but cost increases and unused pins cause noise and waste
Solution Approach 1:
The patent makes a single I/O port perform multiple functions by time-division multiplexing. The port alternates between encoder signal input and temperature signal input, allowing one pin to handle what previously required separate dedicated pins for each function, thus reducing the total pin count while maintaining full signal processing capability
Solution Approach 2:
The patent combines encoder signal lines and temperature signal lines into a single shared I/O port. By merging these previously separate signal paths and using temporal separation (time-division multiplexing), the system reduces the number of required pins while preserving all necessary signal processing functions
2Device complexity
If signal lines are shared to reduce pin count, then device complexity is reduced, but signal detection precision deteriorates due to mixed analogue and digital signals
Solution Approach 1:
The patent segments the signal detection process into distinct time slots. The I/O port is dedicated to encoder signals during one period and exclusively to temperature signals during another period. This temporal segmentation prevents analogue and digital signals from interfering with each other, maintaining detection precision while allowing physical sharing of the signal line
Solution Approach 2:
The patent implements periodic switching between different signal modes. The I/O port alternates between receiving encoder pulses and receiving temperature voltage signals in a regular periodic manner. This periodic action ensures that at any given moment, the port handles only one type of signal, preventing noise contamination while reducing pin requirements
3Device complexity
If a single port processes both analogue and digital signals, then device complexity is reduced, but reliability deteriorates due to signal interference
Solution Approach 1:
The patent dynamically changes the function of the I/O port over time. The port is configured to handle digital encoder signals during one time interval and analogue temperature signals during another time interval. This dynamic reconfiguration ensures that the port is optimized for the specific signal type being processed at each moment, preventing interference and maintaining reliability
Solution Approach 2:
The patent maintains continuous operation by seamlessly transitioning between different signal modes. The switching between encoder signal processing and temperature signal processing occurs without interruption to the overall system function. This continuous action ensures that the single port reliably handles all necessary signals without downtime or loss of functionality
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 configuration enables miniaturization of ICs like microcomputers by allowing analogue and digital signals to be processed at an identical A/D port, reducing pin count and minimizing noise-related errors, while effectively detecting abnormal temperature states and priority signals.
Implementation Method 1
a thermistor that is connected to the A/D input port and outputs an analogue signal to the A/D input port
Implementation Method 2
a switch section that shifts a level of the analogue signal to a low level
Data Source
AI summary
A temperature determination apparatus includes a signal detection section having an A/D input port, a thermistor that is connected to the A/D input port and outputs an analog signal to the A/D input port, and a switch section that shifts a level of the analog signal to a low level. The signal detection section determines that a control signal having a priority higher than that of an output detection process of the thermistor is generated when it is detected that the analog signal to be input to the A/D input port is in the low level.