這次主題是利用Arduino Ethernet shield去控制LED的Blink
1. 幾個比較需要注意的Function:
a. Server
|- begin()
|- available()
b. Client
|- available()
|- readBytesUntil
|- find
|- findUntil
2. Server:
a.begin():
依照官網的敘述:
Tells the server to begin listening for incoming connections.
可以知道begin()是用來告知Server listen是否有連線的request
b. available():
依照官網的敘述:
Gets a client that is connected to the server and has data available for reading. The connection persists when the returned client object goes out of scope; you can close it by calling client.stop().
表示available()會回傳一個client的object -> 此client object為連上Server的client，可以使用client.stop()來中斷連線
3. Client:
a.available():
依照官網的敘述:
Returns the number of bytes available for reading (that is, the amount of data that has been written to the client by the server it is connected to).
在Client和Server的available不同，從官網上得知，Server.available()會回傳一個和Server連線的Client object，而Client.available()會回傳多少Bytes從Server傳送給Client
b.readBytesUntil():
依照官網的敘述:
readBytesUntil() read characters from a stream into a buffer. The function terminates if the terminator character is detected, the determined length has been read, or it times out
此function繼承自Stream，把讀取到的data放到一個buffer直到設定的character被找到為止
c.find():
依照官網的敘述:
find() reads data from the stream until the target string of given length is found The function returns true if target string is found, false if timed out.
這個function是用來讀取data直到想要的string被讀取到了之後會回傳true，並且會把指標停在下一個要開始read data的位址
d.findUntil():
依照官網的敘述:
findUntil() reads data from the stream until the target string of given length or terminator string is found.
使用的方式和find()差不多，但多惹終止搜尋的關鍵string，當搜尋到terminator string會停止搜尋
4. Sample Code:
這次的Sample Code是把Arduino當作Server，類似於Apache Server，並且有CGI(利用分辨POST和GET來處理)在處理Client端的request
#include
#include
byte mac[] = {0xDE,0xAD,0xBE,0xEF,0xFE,0xED};
byte ip[] = {192,168,1,50};
const int MAX_PAGENAME_LEN = 8;
char buffer[MAX_PAGENAME_LEN+1];
EthernetServer server = 80;
void sendHeader(EthernetClient client,char *title){
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println();
client.print("<html><head>$lt;title>");
client.print(title);
client.println("</title><body>");
}
void setup(){
Serial.begin(9600);
Ethernet.begin(mac,ip);
server.begin();
delay(2000);
}
void loop(){
EthernetClient client = server.available();
if(client){
//當Client連上Server候需要保持連線 -> 使用While(client.connected())
while(client.connected()){
//判斷Client是否有資料的request
if(client.available()){
//清空Buffer
memset(buffer,0,sizeof(buffer));
//HTTP request的樣子 -> GET /URL HTTP/1.1
//所以先用找/判斷是什麼HTTP request method
if(client.readBytesUntil('/',buffer,sizeof(buffer))){
buffer[strlen(buffer)-1]='\0';
//如果是POST的方法 -> 執行digitalWrite
if(strcmp(buffer,"POST")==0){
client.find("\n\r");
//找出POST的content
while(client.findUntil("pinD","\n\r")){
int pin = client.parseInt();
int val = client.parseInt();
Serial.print("pin = ");
Serial.print(pin);
Serial.print(" , value = ");
Serial.println(val);
pinMode(pin,OUTPUT);
digitalWrite(pin,val);
}
}
//送出HTML的網頁
sendHeader(client,"Post example");
client.println("<h2>Click buttons to turn pin 8 on or off</h2>");
client.print(
"<form action='/' method='POST'><p><input type='hidden' name='pinD8'");
client.println(" value='0'><input type='submit' value='off'/></form>");
client.print(
"<form action='/' method='POST'><p><input type='hidden' name='pinD8'");
client.print(" value='1'><input type='submit' value='On'/></form>");
client.println("</body></html>");
client.stop();
}
break;
}
}
delay(1);
client.stop();
}
}
run的結果:
上面的程式碼是用HTTP的方式來連接，所以打開瀏覽器可以看到結果
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