qmaw的部落格

(這個標題好難想啊，一直想不到適當的標題)

這次要介紹的是CPU在digitalWrite(HIGH)<->digitalWrite(LOW)雙向切換所需要的時間，參賽選手有Due、Intel Galileo Gen2、Mega ADK、Micro，Nano。

作法是把某個Pin的電位由高拉到低，再由低拉到高，反覆進行，藉此來量測CPU的排程情況以及OUTPUT電位的切換時間，提供給寫程式的人參考。

程式碼(下載)

void setup() {                
  pinMode(12,OUTPUT);
  pinMode(11,OUTPUT);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);
  digitalWrite(12,LOW);  
  digitalWrite(12,HIGH); //1
  digitalWrite(12,LOW); 
  digitalWrite(12,HIGH); //2
  digitalWrite(12,LOW);   
  digitalWrite(12,HIGH); //3
  digitalWrite(12,LOW); 
  digitalWrite(12,HIGH); //4
  digitalWrite(12,LOW); 
  digitalWrite(12,HIGH); //5
  digitalWrite(12,LOW); 
  digitalWrite(12,HIGH); //2_1
  digitalWrite(11,HIGH); //2_1
  digitalWrite(12,LOW); 
  digitalWrite(11,LOW); 
  digitalWrite(12,HIGH); //2_2
  digitalWrite(11,HIGH); //2_2
  digitalWrite(12,LOW); 
  digitalWrite(11,LOW);
  digitalWrite(12,HIGH); //2_3
  digitalWrite(11,HIGH); //2_3
  digitalWrite(12,LOW); 
  digitalWrite(11,LOW);  
  digitalWrite(12,HIGH); //2_4
  digitalWrite(11,HIGH); //2_4
  digitalWrite(12,LOW); 
  digitalWrite(11,LOW);
  digitalWrite(12,HIGH); //2_5
  digitalWrite(11,HIGH); //2_5
  digitalWrite(12,LOW); 
  digitalWrite(11,LOW);
}

// the loop routine runs over and over again forever:
void loop() {
}

其實一開始的pin 12也不用 digitalWrite(12,LOW);這麼多次啦，寫的時候不曉得在想什麼。

接著用邏輯分析儀來量看看結果，這次分別對DUE，Intel Galileo Gen2，MEGA ADK，Nano & Mirco作量測

結果請看下一篇文章。