Microcontroller Pin Ownership Multiplexing for Fixed GPIO Configuration
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Solution Overview
Problem
Microcontrollers with low pin count face limitations in simultaneously controlling multiple GPIO pins due to multiplexing, leading to delays in system initialization and vulnerability to software errors, necessitating external components for fixed functions.
Innovation Solution
Implementing a second level multiplexer to grant exclusive configuration ownership of I/O pads to pin configuration functions, using flash configuration logic or secure control sources like Hardware Security Modules to ensure permanent and error-resistant pin configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple GPIO functions are multiplexed onto each pin in low pin count microcontrollers, then pin utilization efficiency is improved, but the ability to control multiple GPIO pins simultaneously is worsened
Solution Approach 1:
The patent segments the control of I/O pads by introducing a second level multiplexer that divides configuration ownership into dedicated groups. Each group can be independently controlled, allowing simultaneous control of multiple pins within each group while maintaining high pin utilization through the first level multiplexer. This segmentation resolves the contradiction by organizing pins into controllable units.
2Adaptability or versatility
If initialization software is run to configure I/O pins after power up, then pin configuration flexibility is improved, but system initialization time is worsened
Solution Approach 1:
The patent applies preliminary action by pre-configuring pin groups through the second level multiplexer before the microcontroller executes initialization software. The configuration ownership is established in advance, allowing critical pin functions to be ready immediately upon power up while the software initialization proceeds, thereby reducing system initialization time while maintaining flexibility.
3Adaptability or versatility
If I/O pin configuration is controlled by software, then configuration flexibility is improved, but vulnerability to software errors is worsened
Solution Approach 1:
The patent segments configuration control by separating pin configuration into two levels: the first level multiplexer maintains software-controlled flexibility for individual pin configuration, while the second level multiplexer provides group-level ownership control that protects against software errors. Critical pin groups can be locked under specific ownership, making them immune to erroneous software writes while preserving flexibility for non-critical pins.
4Reliability
If external components are added to provide fixed functions, then system reliability is improved, but device complexity is worsened
Solution Approach 1:
The patent merges the function of external fixed-function components into the microcontroller by implementing the second level multiplexer and configuration ownership logic internally. This integration provides the reliability benefits of fixed functions while eliminating the need for external components, thereby reducing device complexity while maintaining or improving system reliability.
Data Source
AI summary
A method to configure an input/output pad that controls a pin of a microcontroller via a first level multiplexer and a central processing unit, grant exclusive configuration ownership of the input/output pad, via a second level multiplexer, to a pin configuration function, and configure exclusively the input/output pad via the pin configuration function. A microcontroller with an input/output pad, a pin controlled by the input/output pad, a first level control circuit to configure the input/output pad, and a second level control circuit to exclusively configure the input/output pad.