Two-Wire Interface for Smart Card Handshaking and Data Transfer
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Solution Overview
Problem
The complexity and cost of smart cards are increased by the high number of wires in existing interfaces between the embedded integrated circuit chip and additional components, such as biometric modules, making secure and reliable connections difficult.
Innovation Solution
A two-wire interface operable in handshaking mode and data transfer mode, where one wire is driven by the first device to provide a clock signal, and the other wire is driven by the second device depending on which device is transmitting data, reducing the number of conductors needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high number of wires is used in the interface between the embedded integrated circuit chip and additional components, then reliable data transfer and communication protocols can be maintained, but the complexity and manufacturing cost of smart cards increase
Solution Approach 1:
The patent combines multiple interface functions (data transmission, clock signaling, handshaking) into a reduced two-wire interface. The first wire carries both data and clock signals in different modes, while the second wire handles both data and handshaking signals, thereby reducing the total number of wires needed while maintaining communication reliability.
Solution Approach 2:
Each wire in the interface is designed to perform multiple functions depending on the operational mode. The first wire serves as both a data line and a clock line, while the second wire functions as both a data line and a handshaking line, allowing the interface to adapt between different communication modes without requiring separate dedicated wires for each function.
2Adaptability or versatility
If a high number of wires is used in the interface, then communication protocols can be fully implemented, but manufacturing cost increases
Solution Approach 1:
The interface merges multiple communication functions into a two-wire configuration, reducing the bill of materials and assembly complexity. By combining data, clock, and handshaking functions into just two wires, the patent lowers manufacturing costs while preserving full communication protocol capability through mode switching.
Solution Approach 2:
The interface dynamically switches between different operational modes (first mode with first wire as clock, second mode with first wire as data) based on communication needs. This dynamic reconfiguration allows the same physical interface to support multiple communication protocols and functions without requiring additional hardware, thereby reducing manufacturing costs.
3Device complexity
If the number of wires in the interface is reduced, then manufacturing cost and complexity decrease, but maintaining reliable connections becomes more difficult
Solution Approach 1:
The interface incorporates handshaking signals transmitted through the second wire to provide feedback between the embedded chip and additional components. This feedback mechanism ensures proper synchronization and error detection, maintaining connection reliability even with the reduced two-wire configuration by allowing devices to coordinate their communication activities.
Solution Approach 2:
The handshaking protocol performs preliminary actions to establish communication readiness before actual data transfer. By using the second wire for handshaking signals, the interface ensures that both devices are properly synchronized and ready for data transmission, thereby maintaining reliability despite the reduced number of wires.
4Ease of manufacture
If a reduced number of wires is used, then manufacturing cost decreases, but the ability to perform handshaking and data transfer simultaneously is compromised
Solution Approach 1:
The interface dynamically switches between operational modes to optimize performance. In the first mode, the first wire functions as a clock line for synchronous data transfer, maximizing data transmission speed. In the second mode, it functions as a data line for asynchronous communication. This dynamic switching allows the interface to maintain high productivity despite the reduced wire count.
Solution Approach 2:
The interface uses periodic mode switching between different operational states. During data transfer phases, the interface operates in modes optimized for high-speed data transmission, while during idle or coordination phases, it uses handshaking modes. This periodic alternation between modes maintains overall data transfer efficiency while accommodating the constraints of a two-wire interface.
Data Source
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AI summary
A two-wire interface (300) for connecting a first device (106) and a second device (108). The two-wire interface (300) is operable in a handshaking mode and a data transfer mode. In the handshaking mode the first wire (302) of the interface (300) is driven by the first device (106) and the second wire (304) of the interface (300) is driven by the second device (108) so that the first (106) and second (108) devices can perform a handshaking sequence. In the data transfer mode one of the first wire (302) and the second wire (304) is driven by one of the first (106) and second (108) devices to provide a clock signal, and the other wire is driven by either the first device (106) or the second device (108) depending which device is transmitting data. Accordingly, the two-wire interfaces (300) are operable in two modes (e.g. handshaking mode and data transfer mode) and one of the wires (302, 304) of the interface (300) may be driven by a different device in the two modes.