编码器续

/* Read Quadrature Encoder
  * Connect Encoder to Pins encoder0PinA, encoder0PinB, and +5V.
  *
  * Sketch by max wolf / www.meso.net
  * v. 0.1 - very basic functions - mw 20061220
  *
  */  


 int val;
 int encoder0PinA = 3;
 int encoder0PinB = 4;
 int encoder0Pos = 0;
 int encoder0PinALast = LOW;
 int n = LOW;

 void setup() {
   pinMode (encoder0PinA,INPUT);  //channel A 插在DIGITAL 3
   pinMode (encoder0PinB,INPUT);  //channel B 插在DIGITAL 4
   Serial.begin (9600);           //debuging输出
 }

 void loop() {
   n = digitalRead(encoder0PinA); //先读取A电位
   if ((encoder0PinALast == LOW) && (n == HIGH)) {  //如果A之前是低电位，现在是高电位
     if (digitalRead(encoder0PinB) == LOW) {        //那么如果B现在低点位
       encoder0Pos--;                               //计数减，反转
     } else {                                       //或者如果B现在是高电位
       encoder0Pos++;                               //计数加，正转
     }
     Serial.print (encoder0Pos);
     Serial.print ("/");
   }
   encoder0PinALast = n;                            //记录本周期A电位，用于下一周期比较
 }