August 2017
Intermediate to advanced
272 pages
5h 32m
Chinese
Content preview from Node.js物聯網裝置開發
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第二章 Arduino 閃爍燈光
然後在 Node.js 環境裡，執行上述腳本程式，便可閃爍 LED：
$ node blink_led
若一切正常，便可看到板子上的 LED 開始亮滅循環。現在是個好時機，你可以比較看
看，以 Arduino（C/C++）撰寫的草稿碼、和以 JavaScript 撰寫的程式，有何差異。
在上面的 JavaScript 程式中，取得了
board
物件，經由這個物件可聆聽從硬體傳來的
「事件（event）」。該範例想要閃爍 LED，首先等待、等到板子發出「ready（準備就
緒）」的事件（代表連線正常），該事件發生後，使用
digitalWrite
與
pinMode.
來改變
板子的功能；從網頁伺服器或網站介面，也能輕鬆地與 JavaScript 物件
board
進行互動
操作（第 9 章和第 10 章將深入介紹）。
微控制器的功能區塊
本章至此，已經看過幾個讓 LED 閃爍的範例，請停下腳步想一想：LED 連接到微控制
器的
腳位
（
pin
），腳位的作用如同是程式碼和某種電子訊號的介面。腳位可根據功能劃
分成群組，以通訊用的輸入腳位和輸出腳位為例，在微控制器晶片裡，腳位可連接到
計
時器
（
timer
），以即時形式操弄訊號。搞清楚腳位的功能並非易事，為了幫助你了解，
最好能準備一張腳位功能圖，隨時查閱（此節最後將會再介紹）。
腳位
微控制器的腳位可分成兩類：
輸入
與
輸出
，腳位可以「驅使」訊號，送往周邊設備與零
件，或是可以「偵測」來自外界的狀態變化。
從技術上來說，輸入與輸出的差異極大，輸入的功用是捕捉訊號的狀態，輸出則是驅使 ...
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