单片机解码PPM信号
遥控器发射机、接收机原理
每个通道信号脉宽0~2ms，变化范围为1~2ms之间。1帧PPM信号长度为20ms，理论上最多可以有10个通道，但是同步脉冲也需要时间，模型遥控器最多9个通道。
本文引用地址：//m.amcfsurvey.com/article/201611/322110.htm
PPM格式
只连接了通道3（油门）
arduino要测量脉宽时间很简单。有专门的库函数pulseIn( )。问题在于这个库函数使用查询方式，程序在测量期间一直陷在这里，CPU利用率太低。因此下面代码采用中断方式，效率很高。
代码参考：http://arduino.cc/forum/index.php/topic,42286.0.html
ARDUINO 代码复制打印
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//read PPM signals from 2 channels of an RC reciever
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//http://arduino.cc/forum/index.php/topic,42286.0.html
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//接收机两个通道分别接arduino的数字口2、3脚
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//Most Arduino boards have two external interrupts: numbers 0 (on digital pin 2) and 1 (on digital pin 3).
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//The Arduino Mega has an additional four: numbers 2 (pin 21), 3 (pin 20), 4 (pin 19), and 5 (pin 18).
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intppm1 =2;
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intppm2 =3;
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unsignedlongrc1_PulseStartTicks,rc2_PulseStartTicks;
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volatileintrc1_val, rc2_val;
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voidsetup(){
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Serial.begin(9600); -
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//PPM inputs from RC receiver -
pinMode(ppm1,INPUT); -
pinMode(ppm2,INPUT); -
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// 电平变化即触发中断 -
attachInterrupt(0, rc1, CHANGE); -
attachInterrupt(1, rc2, CHANGE); -
}
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voidrc1()
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{
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// did the pin change to high or low? -
if(digitalRead(ppm1)==HIGH) -
rc1_PulseStartTicks =micros(); // store the current micros() value -
else -
rc1_val =micros()- rc1_PulseStartTicks; -
}
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voidrc2()
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{
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// did the pin change to high or low? -
if(digitalRead(ppm2)==HIGH) -
rc2_PulseStartTicks =micros(); -
else -
rc2_val =micros()- rc2_PulseStartTicks; -
}
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voidloop(){
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//print values -
Serial.print("channel 1: "); -
Serial.print(rc1_val); -
Serial.print(" "); -
Serial.print("channel 2: "); -
Serial.println(rc2_val); -
}
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