Autonomous Sensor Scanning Module for Low Power Touch Interfaces

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Solution Overview

Problem

Existing sensor scanning technologies in highly integrated electronic devices require significant CPU interaction and bandwidth, leading to performance degradation and increased power consumption, especially in low-power applications where periodic wake-ups of the CPU limit power optimization and increase touch detection latency.

Innovation Solution

The implementation of an autonomous sensor scanning module that operates in CS-DMA, AS-MS, or LP-AOS modes, allowing for CPU-independent scanning by reusing general-purpose resources like DMA engines and finite state machines, which reduces CPU intervention and power consumption while maintaining flexible performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If CPU interaction is used to scan each sensor in the frame, then sensor scanning can be performed, but CPU bandwidth consumption increases and system performance degrades

Engineering Contradiction:

Improvesensor scanning throughputVSAvoidCPU bandwidth consumption

Core Design Contradiction:

ProductivityVSPower

Solution Approach 1:

The sensor scanning module is configured to autonomously perform scanning operations without requiring CPU intervention for each scan. The module can independently configure sensors, initiate scans, and process results, effectively serving itself and eliminating the need for continuous CPU involvement in the scanning process.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The scanning system is divided into independent sensor scanning modules that can operate autonomously. Each module is segmented to handle specific scanning tasks without requiring centralized CPU control, allowing parallel operation and reducing the CPU's workload to only essential coordination functions.

Inventive Principle:

Principle #1Segmentation

2Use of energy by stationary object

If the device is put in sleep mode to conserve power, then power consumption decreases, but touch detection latency increases due to periodic wake-ups

Engineering Contradiction:

Improvedevice power consumptionVSAvoidtouch detection latency

Core Design Contradiction:

Use of energy by stationary objectVSLoss of time

Solution Approach 1:

The sensor scanning module operates in a low-power always-on mode with periodic scanning intervals that can be configured to balance power consumption and response time. This allows the device to maintain sensor monitoring capability without requiring full CPU wake-ups, achieving continuous operation with optimized power usage and reduced latency compared to traditional sleep modes.

Inventive Principle:

Principle #19Periodic action

3Power

If dedicated hardware is used to reduce CPU interaction, then CPU bandwidth is reduced, but die area, power, and cost increase

Engineering Contradiction:

ImproveCPU bandwidth consumptionVSAvoiddie area

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The sensor scanning module is designed to perform multiple functions including sensor configuration, scan initiation, data processing, and result generation within a single integrated unit. This multi-functional approach eliminates the need for separate dedicated hardware components for each function, reducing overall die area while maintaining autonomous operation capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines previously separate functions (sensor configuration, scanning, and result processing) into a single integrated sensor scanning module. This merging of functions reduces the need for additional dedicated hardware and minimizes die area occupation while achieving the goal of reduced CPU interaction.

Inventive Principle:

Principle #5Merging (Combining)

4Productivity

If existing sensor scanning solutions are used, then scanning can be performed, but they are restricted in sensor types, scalability, and capacitance range

Engineering Contradiction:

Improvescanning capabilityVSAvoidsensor type flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The sensor scanning module is designed with dynamic configurability, allowing it to adapt to different sensor types, scanning modes, and capacitance ranges through software configuration rather than hardware constraints. This dynamic approach enables the same hardware to serve multiple sensor types and applications, significantly improving versatility and scalability.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11556205B2Always on low power capacitive matrix autonomous scan

Publication Date: 2023.01.17 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

Disclosed are sensing systems and methods that eliminate CPU intervention or interrupts when performing sensor scans of a touch interface, supports low power sensing operation without requiring periodic wake up of the CPU, and is scalable to multi-channel or multi-chip sensor configuration to support large touch screens or a high number of sensors. A sensor scanning module may operate in a chained-scan using direct memory access (CS-DMA) mode or an autonomous scan-multiple scan (AS-MS) mode to perform scanning of all sensors within a frame without requiring CPU intervention or generating CPU interrupts after every scan in the frame. The sensor scanning module may operate autonomously in a low-power always-on scan (LP-AOS) mode for multiple frames without CPU interaction until a touch event is detected. The CPU may operate in a low power sleep mode during the scan while providing consistent refresh rate and low touch-to-system wake up latency.