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基于充放电原理的电容式触摸按键设计

消耗积分:10 | 格式:rar | 大小:1015 | 2010-11-24

百灵千岛酱

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 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。
Abstract:
 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.
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yuarvin 2013-02-03
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