SPI Multiplex Slave Device for Scalable Bus Interconnects

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Solution Overview

Problem

Existing SPI bus systems require a separate slave select line for each slave device, limiting scalability and necessitating redesigns when adding multiple slave devices, as they cannot efficiently manage communication between a single master device and multiple slave devices without additional interconnects.

Innovation Solution

The implementation of an addressable multiplex slave device that uses a single slave select output pin from the master device to control multiple non-multiplex slave devices through independent slave select output pins, allowing for the selection of specific slave devices via unique identification codes stored in read-only memory, thereby eliminating the need for individual slave select lines for each slave device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If each slave device has an independent slave select line from the master device, then each slave device can be independently selected for communication, but the device complexity and number of interconnects increases significantly when adding multiple slave devices

Engineering Contradiction:

Improveability to communicate with multiple slave devicesVSAvoidnumber of slave select lines and interconnects

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

An intermediary multiplex slave device is introduced between the master device and multiple non-multiplex slave devices. This multiplex slave device receives a single slave select signal from the master device and uses it to control multiple slave devices through internal multiplexing logic, eliminating the need for separate slave select lines for each slave device while maintaining independent communication capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The multiplex slave device performs multiple functions by using a single slave select output pin to control multiple non-multiplex slave devices. Instead of requiring dedicated slave select lines for each slave device, the multiplex slave device universally manages communication with multiple slave devices through shared select signal, reducing the overall complexity of the SPI bus system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If the master device has separate slave select lines for each slave device, then communication with each slave is straightforward, but redesign is required when adding more slave devices

Engineering Contradiction:

Improvesimplicity of SPI bus configurationVSAvoidscalability when adding slave devices

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The multiplex slave device introduces dynamic multiplexing capability to the static SPI bus configuration. It dynamically routes the single slave select signal to different non-multiplex slave devices based on internal control logic, allowing the system to adapt to different numbers and configurations of slave devices without requiring physical redesign of the bus architecture.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The multiplex slave device acts as an intermediary layer that absorbs the complexity of managing multiple slave select lines. It receives the simple single-line select signal from the master device and internally multiplexes it to control multiple slave devices, thereby maintaining ease of manufacture while enabling scalability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple slave devices are connected in a daisy chain configuration, then communication can be established with multiple slaves, but data transmission efficiency and control precision are reduced

Engineering Contradiction:

Improvecapability to connect multiple slave devicesVSAvoiddata transmission efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The system segments slave devices into two categories: multiplex slave devices and non-multiplex slave devices. Multiplex slave devices handle the complex routing and selection logic, while non-multiplex slave devices perform simple data transmission. This segmentation allows efficient communication by separating the multiplexing function from the data transmission function, improving overall productivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multiplex slave device serves as an intermediary that manages the selection and routing of data transmission to different slave devices. By centralizing the multiplexing logic in this intermediary device, the system maintains efficient data transmission paths while supporting multiple slave devices, avoiding the inefficiencies of daisy chain configurations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8433838B2Remote multiplexing devices on a serial peripheral interface bus

Publication Date: 2013.04.30 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A serial peripheral interface (SPI) bus and method of communicating over an SPI bus to multiple slave devices without requiring the master device to have an independent slave select pin for each slave device. The SPI bus comprises an SPI master device coupled to an SPI multiplex slave device and a plurality of SPI non-multiplex slave devices. The SPI multiplex slave device includes an independent slave select (SS) output pin coupled to each one of the SPI non-multiplex slave devices for sending an activation signal to a selected SPI slave device in response to receiving a command from the master device containing identification of the selected SPI slave device.