一种基于PSoC的电容感应式触摸按键系统的设计与实现
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摘要
触摸按键只需要一个薄薄的铜箔层来做按键,所以它使按键厚度几乎为零。由于没有了按键的厚度和重量,易于实现超轻超薄的设计,成为当前消费类产品发展的一个方向。
目前已经有的触摸按键的检测技术,包括:电阻性薄膜测量?场效应检测?和电容感应式检测。但是,电阻性薄膜测量和场效应检测这两种触摸检测技术都有一定的缺陷,譬如高成本,高损耗率等,不便于在消费类产品上大规模应用。
电容感应式(CapSense)触摸按键检测技术,是最近才出现的一个新的研究方向,迄今为止还没有成熟的公开的设计方案。国外目前有采用ASIC芯片来实现电容感应检测,但是,采用ASIC芯片的实现方式,设计不够灵活且按键数目受限不易扩展。
本论文基于PSoC(Programmable System on chip,可编程片上系统)这种通用芯片,采用软件和硬件相结合的设计方式,设计和实现了一个低成本,设计灵活而且易实现易扩展的电容感应式触摸按键系统,易于在消费类产品方向大批量应用和推广。
本文首先了解和分析了电容感应的原理,也介绍了PSoC芯片的结构和特点。根据电容感应的原理,设计了系统的整体方案,并利用PSoC内部的硬件资源具体设计了硬件对感应电容的检测电路,研究并给出了该硬件系统的信号处理流程和算法。同时设计完成软件部分,包括设计软件系统的处理流程和按键判定算法。其中,通过采用输入模拟复用的设计,实现了按键的可扩展性;对软硬件采取模块化的设计,且预留出参数调整的接口,所以可以很方便的进行调试,升级,或者将该系统移植到其他类似应用上,充分保证了方案的易实现性。通过实验了解到,按键和周边PCB布局设计对感应电容和检测电路的输出结果都有直接的影响,所以通过大量实验,给出了他们相互关系的统计模型。并且通过测试,发现了在实际应用中可能出现的噪声干扰等问题,实验给出通过软件和硬件手段解决问题的方法。
最后,通过实际应用对系统作了验证测试,并分析了本文研究的系统在滚动条和触摸板方面的衍伸应用的思路,对此项电容感应式触摸按键技术的发展方向提出了展望。
Touch button only need a pad on the PCB to be button, so it makes the button height nearly be zero. Without a traditional button’s height and weight, touch button will help consumer product be slim and light, which is a trend of consumer products now.
In available touch button detection technology, there is : Resistor Board sense (detecting the touch action by voltage change on resistor board), Electric field sense (detecting the touch action by electric field change) , and Cap Sense (detecting the touch action by cap change on button pad). In which the former two ways have weakness of high BOM cost and low design flexibility.
It’s a new technology of using CapSense theory to implement Touch Button detection, and there isn’t any available or open solution now. It’s said CapSense system once did by ASIC chips, but ASIC chips will have poor design flexibility.
In my CapSense touch button system, by CapSense theory, I’ll use a PSoC (Programmable System on Chip) chip to implement the system. The system will be low cost and has design flexibility, specially be easy to expand new buttons in the system, which should be proper for quick development in consumer products.
In this thesis, first I’ll analysis the CapSense theory, and introduce PSoC’s structure. By CapSense theory, I analysis and design the system solution; use hardware resource in PSoC to design the hardware detection circuit , study and design the signal processing in the circuit. Meanwhile I design the software portion using PSoC’s MCU core, including the system processing and how to make decision on touch action by detected data. By test result, I design the button size and PCB layout to get the best performance of CapSense, and show their relationship model with system output according to a lot of test data. Also I give my way of solving issues found in test, including noise issue, etc..
Finally by real test and usage I verify the system, and have a simple study of the system’s expanded usage on Slide or TouchPad.
目前已经有的触摸按键的检测技术,包括:电阻性薄膜测量?场效应检测?和电容感应式检测。但是,电阻性薄膜测量和场效应检测这两种触摸检测技术都有一定的缺陷,譬如高成本,高损耗率等,不便于在消费类产品上大规模应用。
电容感应式(CapSense)触摸按键检测技术,是最近才出现的一个新的研究方向,迄今为止还没有成熟的公开的设计方案。国外目前有采用ASIC芯片来实现电容感应检测,但是,采用ASIC芯片的实现方式,设计不够灵活且按键数目受限不易扩展。
本论文基于PSoC(Programmable System on chip,可编程片上系统)这种通用芯片,采用软件和硬件相结合的设计方式,设计和实现了一个低成本,设计灵活而且易实现易扩展的电容感应式触摸按键系统,易于在消费类产品方向大批量应用和推广。
本文首先了解和分析了电容感应的原理,也介绍了PSoC芯片的结构和特点。根据电容感应的原理,设计了系统的整体方案,并利用PSoC内部的硬件资源具体设计了硬件对感应电容的检测电路,研究并给出了该硬件系统的信号处理流程和算法。同时设计完成软件部分,包括设计软件系统的处理流程和按键判定算法。其中,通过采用输入模拟复用的设计,实现了按键的可扩展性;对软硬件采取模块化的设计,且预留出参数调整的接口,所以可以很方便的进行调试,升级,或者将该系统移植到其他类似应用上,充分保证了方案的易实现性。通过实验了解到,按键和周边PCB布局设计对感应电容和检测电路的输出结果都有直接的影响,所以通过大量实验,给出了他们相互关系的统计模型。并且通过测试,发现了在实际应用中可能出现的噪声干扰等问题,实验给出通过软件和硬件手段解决问题的方法。
最后,通过实际应用对系统作了验证测试,并分析了本文研究的系统在滚动条和触摸板方面的衍伸应用的思路,对此项电容感应式触摸按键技术的发展方向提出了展望。
Touch button only need a pad on the PCB to be button, so it makes the button height nearly be zero. Without a traditional button’s height and weight, touch button will help consumer product be slim and light, which is a trend of consumer products now.
In available touch button detection technology, there is : Resistor Board sense (detecting the touch action by voltage change on resistor board), Electric field sense (detecting the touch action by electric field change) , and Cap Sense (detecting the touch action by cap change on button pad). In which the former two ways have weakness of high BOM cost and low design flexibility.
It’s a new technology of using CapSense theory to implement Touch Button detection, and there isn’t any available or open solution now. It’s said CapSense system once did by ASIC chips, but ASIC chips will have poor design flexibility.
In my CapSense touch button system, by CapSense theory, I’ll use a PSoC (Programmable System on Chip) chip to implement the system. The system will be low cost and has design flexibility, specially be easy to expand new buttons in the system, which should be proper for quick development in consumer products.
In this thesis, first I’ll analysis the CapSense theory, and introduce PSoC’s structure. By CapSense theory, I analysis and design the system solution; use hardware resource in PSoC to design the hardware detection circuit , study and design the signal processing in the circuit. Meanwhile I design the software portion using PSoC’s MCU core, including the system processing and how to make decision on touch action by detected data. By test result, I design the button size and PCB layout to get the best performance of CapSense, and show their relationship model with system output according to a lot of test data. Also I give my way of solving issues found in test, including noise issue, etc..
Finally by real test and usage I verify the system, and have a simple study of the system’s expanded usage on Slide or TouchPad.
引文
[1] PSoC 片上系统的原理与应用, 何永义,郭帅,王文斌,田应仲等编著, 上海大学出版社
[2] 触摸式可编程终端, 田明等编著, 机械工业出版社
[3] 数字电子技术基础, 阎石编, 高等教育出版社
[4] 片上系统可重用设计方法学(第三版), 沈戈,罗旻,张欣等译, 电子工业出版社
[5] 汇编语言程序设计,罗云彬,电子工业出版社
[6] PSoC Mixed Signal Array Data Sheet, Cypress MicroSystems
[7] PSoC Designer Assembly language User Guide(Rev.B) [M]2005, Cypress MicroSystems
[8] PSoC Designer C language User Guide(Rev.D) [M] 2005, Cypress MicroSystems
[9] PSoC Mixed Signal Array Technical Reference Manual (Trm 1.21) [M]2005, Cypress MicroSystems
[10] PSoC Programmer User Guide(Rev.E) [M]2005, Cypress MicroSystems
[11] PSoC Integrated Development Environment User Guide(Rev.E) [M]2005, Cypress MicroSystems
[12] PSoC ICE Connection and Troubleshooting Guide(Rev.C) [M]2005, Cypress MicroSystems
[13] Low-Cost Touch Controls with Charge-Transfer Sensing, Hal Philipp, NE Asia Issue, 2005
[14] Digital Sensors Enhance Brand Image, David Simpson, Appliance Magazine, 2005
[15] Touch Screen Selection Guide, Nortech Engineering
[16] Charge-transfer Sensing-based Touch Controls Facilitate Creative Interfaces, Hal Philipp, ECN,2005
[17] Through-Glass Touch Technology, Hal Philipp,
[18] Capacitive Sensors, Baxter Larry K, IEEE Press,1997
[2] 触摸式可编程终端, 田明等编著, 机械工业出版社
[3] 数字电子技术基础, 阎石编, 高等教育出版社
[4] 片上系统可重用设计方法学(第三版), 沈戈,罗旻,张欣等译, 电子工业出版社
[5] 汇编语言程序设计,罗云彬,电子工业出版社
[6] PSoC Mixed Signal Array Data Sheet, Cypress MicroSystems
[7] PSoC Designer Assembly language User Guide(Rev.B) [M]2005, Cypress MicroSystems
[8] PSoC Designer C language User Guide(Rev.D) [M] 2005, Cypress MicroSystems
[9] PSoC Mixed Signal Array Technical Reference Manual (Trm 1.21) [M]2005, Cypress MicroSystems
[10] PSoC Programmer User Guide(Rev.E) [M]2005, Cypress MicroSystems
[11] PSoC Integrated Development Environment User Guide(Rev.E) [M]2005, Cypress MicroSystems
[12] PSoC ICE Connection and Troubleshooting Guide(Rev.C) [M]2005, Cypress MicroSystems
[13] Low-Cost Touch Controls with Charge-Transfer Sensing, Hal Philipp, NE Asia Issue, 2005
[14] Digital Sensors Enhance Brand Image, David Simpson, Appliance Magazine, 2005
[15] Touch Screen Selection Guide, Nortech Engineering
[16] Charge-transfer Sensing-based Touch Controls Facilitate Creative Interfaces, Hal Philipp, ECN,2005
[17] Through-Glass Touch Technology, Hal Philipp,
[18] Capacitive Sensors, Baxter Larry K, IEEE Press,1997