Multiplexed I2C Bus Interface Pin Reduction

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Solution Overview

Problem

Electronic devices, such as e-readers and smartphones, face frequent battery depletion due to limited battery life, necessitating frequent charging and the use of external batteries, which require multiple interconnect pins for connection, increasing complexity and pin count.

Innovation Solution

A system and method utilizing a multiplexed I2C interface with a single interconnect pin for both data operations and interrupt/signaling, reducing the number of pins needed by using the SDA line for both purposes, and incorporating an external battery monitor to detect docking and undocking, as well as perform data operations, thereby simplifying the connector design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple interconnect pins are used for connection between electronic device and external battery, then data operations and interrupt signaling can be performed separately, but the connector complexity and pin count increase

Engineering Contradiction:

Improvedata operations and interrupt signalingVSAvoidconnector complexity and pin count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the interrupt signal line and I2C data line into a single shared physical connection. The same interconnect pin serves dual purposes: detecting external battery docking/undocking events and performing bidirectional data communication via I2C protocol, thereby reducing pin count while maintaining full functionality

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shared interconnect pin is designed to perform multiple functions: it detects docking events through voltage level changes, enables bidirectional data communication using I2C master/slave protocols, and supports both read and write operations. This multi-functional design eliminates the need for separate dedicated pins for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If separate interconnect pins are used for docking detection and data operations, then functional separation is achieved, but the connection process becomes more complex

Engineering Contradiction:

Improvefunctional separationVSAvoidconnection process

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system dynamically switches the role of the shared SDA pin between interrupt detection mode and I2C data communication mode based on operational context. The microcontroller changes the pin's electrical characteristics and protocol behavior dynamically, allowing it to function as an interrupt input during docking events and as an I2C bidirectional data line during communication, thereby simplifying the physical connection while maintaining functional separation through software control

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10298028B1Systems and methods for dynamic configuration and control of bus interface

Publication Date: 2019.05.21 AMAZON TECH INC

AI summary

Method and systems for configuration and control of an inter-integrated circuit (I2C) bus interface are described. An electronic device that may be connected to an external battery device via a modified connector is also described. The connector has multiple interconnect pins, and one of the interconnect pins of the connector is multiplexed to receive data operation and interrupt or signaling operation on a single line. The single line is configured to not only detect a connection with the external battery device, but also to perform data operations including read/write operations between the electronic device and the external battery device.