基于充放电原理的电容式触摸按键设计  

Capacitive touch sensor design based on charging/discharging principle

作　　者：田野[1] 廖明燕[1] 

机构地区：[1]中国石油大学(华东)信息与控制工程学院,山东东营257061

出　　处：《电子设计工程》2010年第10期142-144,共3页Electronic Design Engineering

基　　金：中国石油科技创新基金研究项目(2009D-5006-06-02)

摘　　要：为降低触摸按键的硬件成本,设计了一种简易的触摸按键电路,其基本原理是通过检测RC回路的充放电时间来判断有无按键被按下,当未触碰按键时,充放电时间维持不变;当触碰按键时,充放电时间改变。由MSP430单片机的每两个I/O引脚构成一个充放电回路对,并为按键充放电,充电时引脚检测上升沿中断,放电时引脚检测下降沿中断,求出平均值,记录充放电时间。该方案仅需要1片单片机而无需其他专用检测电路,简单、可靠,且最有效地降低了硬件成本。To decrease the hardware cost of touch senor, a simple and easy touch sensor is designed. The basic principle is that the touch sensor is pressed or not can be judged by detecting the variation of charging/discharging period. The charging/discharging period is constant when no sensor-pad is pressed, as the finger touches the sensor-pad the charging/ discharging period will be changed. Each two I/O pins of MSP430 composed a charging/discharging loop, and charge/ discharge the sensor-pad. The rising edge interrupt is detected when charging the sensor-pad, and the falling edge interrupt is detected when discharging the sensor-pad. The mean time is calculated, and the charging/discharging period is recorded. This method only requires one MCU without any other special detection chips. This design is simple, reliable and reduces hardware costs effectively.

关 键 词：触摸按键 电容检测 MSP430 PCB布局 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]