利用ESP-WROOM-02和天气API制作发光的圣诞节雪人-电子发烧友网

这篇文章来源于DevicePlus.com英语网站的翻译稿。

许多应用都用过ESP-WROOM-02，并且通过Arduino程序利用了该开发板的wifi通信功能。今天，我们要实现一个更具创意性的项目，根据天气API的天气信息制作另一款炫丽的圣诞装饰品。

今天的电子设计技巧

估计完成时间：90分钟

所需部件

ESP-WROOM-02 开发板

面包板

LED – 绿色

电阻220Ω/180Ω/91Ω

高功率RGB LED

为了启用ESP-WROOM-02开发板的Arduino程序无线通信功能，我想首先尝试一个示例程序。选择File → Sketch Example → ESP 8266 WiFi → WiFi Web Server。该示例程序负责处理与Arduino的Wifi通信。

图1 加载程序示例

这个示例程序能让ESP-WROOM-02成为服务器。程序启动后，它会一直等待来自其他终端的请求，当收到带有参数的请求后，程序就会处理该参数。在我们的例子中，我们将使用这个程序来点亮LED。

我想使用上次的电路进行测试。将示例程序中的引脚“2”更改为引脚“13”。

图2 LED控制电路

/*
 * This sketch demonstrates how to set up a simple HTTP-like server.
 * The server will set a GPIO pin depending on the request
 * https://server_ip/gpio/0 will set the GPIO2 low,
 * https://server_ip/gpio/1 will set the GPIO2 high
 * server_ip is the IP address of the ESP8266 module, will be
 * printed to Serial when the module is connected.
 */
 
#include 
#include 
 
const char *ssid = "Provide SSID of wireless router here";
const char *password = "Provide the wireless router password here";
 
// Create an instance of the server
// specify the port to listen on as an argument
WiFiServer server(80);
 
void setup() {
 Serial.begin(115200);
 delay(10);
 
 // prepare GPIO2
 pinMode(2, OUTPUT);
 digitalWrite(2, 0);
  
 // Connect to WiFi network
 Serial.println();
 Serial.println();
 Serial.print("Connecting to ");
 Serial.println(ssid);
  
 WiFi.begin(ssid, password);
  
 while (WiFi.status() != WL_CONNECTED) {
 delay(500);
 Serial.print(".");
 }
 Serial.println("");
 Serial.println("WiFi connected");
  
 // Start the server
 server.begin();
 Serial.println("Server started");
 
 // Print the IP address
 Serial.println(WiFi.localIP());
}
 
void loop() {
 // Check if a client has connected
 WiFiClient client = server.available();
 if (!client) {
 return;
 }
  
 // Wait until the client sends some data
 Serial.println("new client");
 while(!client.available()){
 delay(1);
 }
  
 // Read the first line of the request
 String req = client.readStringUntil('r');
 Serial.println(req);
 client.flush();
  
 // Match the request
 int val;
 if (req.indexOf("/gpio/0") != -1)
 val = 0;
 else if (req.indexOf("/gpio/1") != -1)
 val = 1;
 else {
 Serial.println("invalid request");
 client.stop();
 return;
 }
 
  
 // Set GPIO2 according to the request
 digitalWrite(2, val);
  
 client.flush();
 
 // Prepare the response
 String s = "HTTP/1.1 200 OKrnContent-Type: text/htmlrnrnrnrnGPIO is now ";
 s += (val)high":"low";
 s += "n";
 
 // Send the response to the client
 client.print(s);
 delay(1);
 Serial.println("Client disonnected");
 
 // The client will actually be disconnected
 // when the function returns and 'client' object is detroyed
}

启动程序后，请尝试连至路由器。如果已经连接，那么系统会在串行监视器上显示IP地址等。所以，请尝试从浏览器访问该IP地址。连至/gpio/1时，LED亮起；连至/gpio/0时，LED熄灭。

图3 Wifi访问成功

图4 智能手机连接

通过程序控制伺服电机

接下来我们通过一个实际例子试着用Wifi控制伺服电机。伺服电机的控制基本上应与LED控制相同。我将在LED程序中添加一些修改，并通过从浏览器访问时添加一些HTML。

#include 
#include 
 
const char *ssid = "Provide SSID of wireless router here";
const char *password = "Provide the wireless router password here";
 
Servo myservo;
WiFiServer server(80);
 
void setup() {
 Serial.begin(115200);
 delay(10);
  
 Serial.println();
 Serial.println();
 Serial.print("Connecting to ");
 Serial.println(ssid);
 
 WiFi.begin(ssid, password);
  
 while (WiFi.status() != WL_CONNECTED) {
 delay(1500);
 Serial.print(".");
 }
 Serial.println("");
 Serial.println("WiFi connected");
  
 server.begin();
 Serial.println("Server started");
 
 Serial.println(WiFi.localIP());
 
 myservo.attach(2);
}
 
void loop() {
 WiFiClient client = server.available();
 if (!client) {
 return;
 }
  
 Serial.println("new client");
 while(!client.available()){
 delay(1);
 }
  
 String req = client.readStringUntil('r');
 Serial.println(req);
 client.flush();
  
 // Match the request
 int val;
 if (req.indexOf("/gpio/0") != -1){ val = 0; }
 else if (req.indexOf("/gpio/30") != -1){ val = 30; }
 else if (req.indexOf("/gpio/60") != -1){ val = 60; }
 else if (req.indexOf("/gpio/90") != -1){ val = 90; }
 else if (req.indexOf("/gpio/120") != -1){ val = 120; }
 else if (req.indexOf("/gpio/150") != -1){ val = 150; }
 else {
 Serial.print("REQ:");
 Serial.println(req);
 Serial.println("invalid request");
 client.stop();
 return;
 }
 
 myservo.write(val);
  
 client.flush();
 
 String s = "HTTP/1.1 200 OKrnContent-Type: text/htmlrnrnrnrnGPIO is now ";
 s += (val)high":"low";
 s += "

"; s += "

n"; s += "

120

n"; s += "

150

n"; s += "

n"; s += "n"; client.print(s); delay(1); Serial.println("Client disonnected"); }

在这个程序中，浏览器显示的角度为0到150。当点击每个数值时，伺服电机会移动到一个指定角度。