Sharing SPI and I2C Lines via Multiplexer Isolation
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Solution Overview
Problem
The challenge lies in sharing communication lines between SPI and I2C buses, as incompatible signaling types can cause subordinate devices to malfunction, and existing solutions struggle with routing multiple buses through signal restrictions due to limited connector terminals.
Innovation Solution
A serial bus communication subsystem that shares communication lines between SPI and I2C buses using a sharing control mechanism, such as a shared mutex object or time-division multiplexer, isolates I2C devices during SPI bus transfers and vice versa, ensuring exclusive use of shared lines for each bus to prevent interference and reduce the total number of allocated lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If communication lines are shared between SPI and I2C buses, then the number of communication lines is reduced, but signaling incompatibility causes device malfunctions
Solution Approach 1:
The patent implements dynamic configuration of communication lines by using a multiplexer to switch between SPI and I2C bus modes. The system can dynamically change the signaling type on shared communication lines based on which bus needs to communicate, allowing the same physical lines to adapt to different protocol requirements without causing device malfunctions
Solution Approach 2:
The patent introduces a multiplexer as an intermediary device between the communication lines and the buses. This mediator controls which bus (SPI or I2C) can use the shared communication lines at any given time, preventing signaling conflicts while enabling line sharing. The multiplexer acts as a gatekeeper that ensures only one bus type drives the shared lines at a time
2Adaptability or versatility
If multiple buses are routed through signal restrictions, then connectivity is improved, but limited connector terminals cause routing difficulties
Solution Approach 1:
The patent merges the communication lines of SPI and I2C buses by using a multiplexer to share the same physical communication lines between the two bus types. Instead of requiring separate dedicated lines for each bus, the system combines them into a shared resource, reducing the total number of connector terminals needed while maintaining full routing capability for both buses
Solution Approach 2:
The patent makes the communication lines universal by enabling them to serve multiple functions - they can operate as SPI bus lines or I2C bus lines depending on the multiplexer configuration. This multi-functionality allows the same physical infrastructure to support different communication protocols, improving adaptability without increasing connector complexity
Data Source
AI summary
A process includes coupling a push-pull driver of a first bus device to a plurality of communication lines that are associated with a first bus to allow the first bus device to access the first bus using push-pull signaling. The process includes sharing a set of communication lines with the second bus. The sharing includes coupling an open drain driver of a second bus device to the set of communication lines to allow the second bus device to access the second bus using open drain signaling. The sharing includes using the set of communication lines in first time periods in which the first bus device accesses the first bus and using the set of communication lines in second time periods other than the first time periods in which the second bus device accesses the second bus. The sharing includes isolating a push-pull driver of the first bus device from the set of communication lines responsive to the second time periods.