Master-Slave Touch Sensing for Large Panel Clock Synchronization
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Solution Overview
Problem
Existing touch sensing systems face challenges in efficiently processing large or high-resolution touch sensor panels due to limitations in the number of drive and sense lines that can be handled by a single controller ASIC, leading to inadequate support and increased costs for designing new controllers to handle larger surfaces.
Innovation Solution
A master/slave touch controller configuration is implemented, where the master and slave controllers transmit drive signals and receive sense signals, with synchronized clock signals to ensure in-phase processing, allowing for coordinated operation and reduced costs by using existing controllers, and enabling more efficient handling of larger touch sensing surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single controller ASIC is used to handle touch sensing, then the device complexity is low, but the capability to support large or high-resolution touch sensor panels is insufficient
Solution Approach 1:
The touch controller is divided into a master controller and one or more slave controllers. Each controller handles a portion of the drive lines and sense lines, enabling support for large or high-resolution touch sensor panels while keeping individual controller complexity manageable. The master controller coordinates the slave controllers through synchronized clock signals and communication sequences.
2Adaptability or versatility
If multiple controllers are used to handle larger touch sensor panels, then the adaptability increases, but the number of connections and costs increase
Solution Approach 1:
Multiple controllers (master and slave) are merged into a coordinated system that shares clock signals and communication protocols. The slave controllers use the master's clock signals and communicate through standardized sequences, reducing the need for separate connection architectures and lowering overall system costs while maintaining adaptability for large panels.
3Ease of operation
If slave controllers generate independent clock signals, then each controller operates autonomously, but the sense signal processing becomes out-of-phase reducing accuracy
Solution Approach 1:
The master controller's clock signals serve as an intermediary that synchronizes the slave controllers. Instead of each controller generating independent clock signals, the slave controllers use the master's clock signals (at the same frequency and phase) to coordinate their drive signal generation and sense signal processing, ensuring in-phase operation and measurement accuracy while maintaining operational coordination.
Data Source
AI summary
Touch sensing can be accomplished using master/slave touch controllers that transmit drive signals to a touch surface and process sense signals including superpositions resulting from master/slave drive signals. The master/slave can drive and sense different sets of lines, respectively, of the touch surface. A communication link between master/slave can be established by transmitting a clock signal between master/slave, transmitting a command including sequence information to the slave, and initiating a communication sequence from the clock signal and sequence information. The slave can receive/transmit communications from/to the master during first/second portions of the communication sequence, respectively. Touch sensing operations can be synchronized between master/slave by transmitting a command including phase alignment information from master to slave, and generating slave clock signals based on the clock signal and the phase alignment information, such that sense signal processing by master clock signals are in-phase with sense signal processing by slave clock signals.