在這篇教學中,我們將擴展 Arduino Web Server 範例 ,以便可以通過瀏覽器向 Arduino 發送指令。
我們將透過存取 /on
的 URL 點亮 Arduino 上的內建 LED,並透過開啟 /off
的 URL 來關閉它。其他任何指令都將無效。
以下是來自其他教學的程式碼:
#include <SPI.h>
#include <WiFiNINA.h>
WiFiServer server(80);
void setup() {
char ssid[] = SECRET_SSID;
char pass[] = SECRET_PASS;
Serial.begin(9600);
while (!Serial);
int status = WL_IDLE_STATUS;
while (status != WL_CONNECTED) {
Serial.print("Connecting to ");
Serial.println(ssid);
status = WiFi.begin(ssid, pass);
delay(5000);
}
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
server.begin();
}
void loop() {
WiFiClient client = server.available();
if (client) {
String line = "";
while (client.connected()) {
if (client.available()) {
char c = client.read();
Serial.write(c);
if (c != '\n' && c != '\r') {
line += c;
}
if (c == '\n') {
if (line.length() == 0) {
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close");
client.println();
client.println("<!DOCTYPE HTML>");
client.println("<html>");
client.println("test");
client.println("</html>");
break;
} else {
line = "";
}
}
}
}
client.stop();
}
}
在最後的 else
部分,我們可以檢查完整的一行內容,以便在清除內容之前做檢查。在這個案例中,我們可以檢查是否為 GET /on
或 GET /off
,以檢測所要執行的指令:
String command = "";
// ...
if (line.startsWith("GET /on ")) {
command = "on";
}
if (line.startsWith("GET /off ")) {
command = "off";
}
在準備好回覆時,我們可以檢查指令並將 LED 打開或關閉:
if (command == "on") {
digitalWrite(LED_BUILTIN, HIGH);
} else if (command == "off") {
digitalWrite(LED_BUILTIN, LOW);
}
我們還可以回覆一個確認訊息,例如:
client.println("Turned the LED " + command);
完成了!現在將程式碼燒錄到 Arduino 上,並呼叫 /on
或 /off
的 URL。
我在我的本地網路路由器中為 Arduino 預留了一個靜態 IP,並且在 /etc/hosts
檔案中將其命名為 arduino.local
,因此可以透過 http://arduino.local/on
打開 LED,或透過 http://arduino.local/off
關閉 LED。
以下是完整的程式碼:
#include <SPI.h>
#include <WiFiNINA.h>
WiFiServer server(80);
void setup() {
char ssid[] = SECRET_SSID;
char pass[] = SECRET_PASS;
Serial.begin(9600);
while (!Serial);
int status = WL_IDLE_STATUS;
while (status != WL_CONNECTED) {
Serial.print("Connecting to ");
Serial.println(ssid);
status = WiFi.begin(ssid, pass);
delay(5000);
}
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
server.begin();
}
void loop() {
WiFiClient client = server.available();
if (client) {
String line = "";
String command = "";
while (client.connected()) {
if (client.available()) {
char c = client.read();
Serial.write(c);
if (c != '\n' && c != '\r') {
line += c;
}
if (c == '\n') {
if (line.length() == 0) {
if (command == "on") {
digitalWrite(LED_BUILTIN, HIGH);
} else if (command == "off") {
digitalWrite(LED_BUILTIN, LOW);
}
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close");
client.println();
client.println("<!DOCTYPE HTML>");
client.println("<html>");
client.println("Turned the LED " + command);
client.println("</html>");
break;
} else {
if (line.startsWith("GET /on ")) {
command = "on";
}
if (line.startsWith("GET /off ")) {
command = "off";
}
line = "";
}
}
}
}
client.stop();
}
}