Arduino Nano 33 IoT

# Arduino Nano 33 IoT (SAMD21 + NINA-W102) 代码例程

## 例程 1：WiFi 连接 + HTTP 请求（GET）

```cpp
// Nano 33 IoT - WiFi 连接 + HTTP GET 请求
#include <WiFiNINA.h>
#include <ArduinoHttpClient.h>

const char* ssid = "YOUR_SSID";
const char* pass = "YOUR_PASSWORD";
const char* server = "api.github.com";

WiFiClient wifi;
HttpClient client(wifi, server, 443);  // HTTPS

void setup() {
    Serial.begin(115200);
    while (!Serial);
    
    pinMode(LED_BUILTIN, OUTPUT);
    
    // 连接 WiFi
    Serial.print("Connecting to WiFi");
    WiFi.begin(ssid, pass);
    
    int attempts = 0;
    while (WiFi.status() != WL_CONNECTED && attempts < 30) {
        digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
        Serial.print(".");
        delay(1000);
        attempts++;
    }
    
    if (WiFi.status() == WL_CONNECTED) {
        digitalWrite(LED_BUILTIN, HIGH);
        Serial.println("\nWiFi connected!");
        Serial.print("IP: ");
        Serial.println(WiFi.localIP());
        Serial.print("RSSI: ");
        Serial.println(WiFi.RSSI());
    } else {
        Serial.println("\nWiFi connection failed!");
    }
}

void loop() {
    if (WiFi.status() == WL_CONNECTED) {
        Serial.println("Making HTTPS GET request...");
        client.get("/users/octocat/repos");
        
        int statusCode = client.responseStatusCode();
        Serial.print("Status: ");
        Serial.println(statusCode);
        
        String response = client.responseBody();
        Serial.print("Response: ");
        Serial.println(response.substring(0, 200));  // 前200字符
    }
    
    delay(30000);  // 每30秒请求一次
}
```

---

## 例程 2：Arduino IoT Cloud 最小示例

```cpp
// Nano 33 IoT - Arduino IoT Cloud 连接示例
// 在 Arduino IoT Cloud (create.arduino.cc) 创建 Thing 后自动生成代码框架
#include "thingProperties.h"

void setup() {
    Serial.begin(115200);
    delay(1500);  // 等待串口稳定
    
    // 初始化属性（由 IoT Cloud 自动生成）
    initProperties();
    
    // 连接 WiFi 和 IoT Cloud
    ArduinoCloud.begin(ArduinoIoTPreferredConnection);
    
    // 调试信息
    setDebugMessageLevel(2);
    ArduinoCloud.printDebugInfo();
}

void loop() {
    ArduinoCloud.update();
    
    // 你的代码（读取传感器、控制执行器等）
    // 示例：每隔一段时间更新云端变量
    static unsigned long lastUpdate = 0;
    if (millis() - lastUpdate > 5000) {
        lastUpdate = millis();
        // cloudVariable = analogRead(A0);  // 自动同步到云端
    }
}

// IoT Cloud 回调（当云端变量变化时触发）
void onCloudVariableChange() {
    Serial.println("Cloud variable changed!");
    // 响应云端指令
}
```

---

## 例程 3：DAC 输出 — A0 模拟电压输出

```cpp
// Nano 33 IoT - A0 DAC 输出（10位，0-3.3V）
// 此功能为 Nano 33 IoT 独有（Nano 33 BLE 无DAC）

void setup() {
    Serial.begin(115200);
    analogWriteResolution(10);  // 10位DAC
}

void loop() {
    // 锯齿波
    for (int i = 0; i < 1024; i += 4) {
        analogWrite(A0, i);
        delayMicroseconds(100);
    }
    
    // 正弦波（查找表）
    static const int sineTable[] = {
        512,530,548,565,583,600,617,634,650,666,
        681,696,710,723,736,748,759,769,778,786,
        794,800,805,809,813,815,817,817,817,815,
        813,809,805,800,794,786,778,769,759,748,
        736,723,710,696,681,666,650,634,617,600,
        583,565,548,530,512,493,475,458,440,423,
        406,389,373,357,342,327,313,300,287,275,
        264,254,245,237,229,223,218,214,210,208,
        206,206,206,208,210,214,218,223,229,237,
        245,254,264,275,287,300,313,327,342,357,
        373,389,406,423,440,458,475,493
    };
    
    for (int i = 0; i < 100; i++) {
        analogWrite(A0, sineTable[i]);
        delayMicroseconds(200);
    }
}
```

---

## 例程 4：6轴IMU 数据读取

```cpp
// Nano 33 IoT - LSM6DS3 加速度计 + 陀螺仪
#include <Arduino_LSM6DS3.h>

void setup() {
    Serial.begin(115200);
    while (!Serial);
    
    if (!IMU.begin()) {
        Serial.println("IMU init failed!");
        while (1);
    }
    
    Serial.println("IMU ready.");
    Serial.println("AccelX,AccelY,AccelZ,GyroX,GyroY,GyroZ");
}

void loop() {
    float ax, ay, az, gx, gy, gz;
    
    if (IMU.accelerationAvailable() && IMU.gyroscopeAvailable()) {
        IMU.readAcceleration(ax, ay, az);
        IMU.readGyroscope(gx, gy, gz);
        
        // CSV 格式输出（便于串口绘图器）
        Serial.print(ax); Serial.print(",");
        Serial.print(ay); Serial.print(",");
        Serial.print(az); Serial.print(",");
        Serial.print(gx); Serial.print(",");
        Serial.print(gy); Serial.print(",");
        Serial.println(gz);
    }
    
    delay(10);
}
```

---

## 例程 5：WiFi Web 服务器（控制 GPIO）

```cpp
// Nano 33 IoT - 简易 Web 服务器控制 LED
#include <WiFiNINA.h>

const char* ssid = "YOUR_SSID";
const char* pass = "YOUR_PASSWORD";

WiFiServer server(80);

void setup() {
    Serial.begin(115200);
    pinMode(LED_BUILTIN, OUTPUT);
    digitalWrite(LED_BUILTIN, LOW);
    
    WiFi.begin(ssid, pass);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }
    
    Serial.println("\nWiFi connected!");
    Serial.print("Web server at: http://");
    Serial.println(WiFi.localIP());
    
    server.begin();
}

void loop() {
    WiFiClient client = server.available();
    if (!client) return;
    
    Serial.println("New client.");
    String request = "";
    while (client.connected()) {
        if (client.available()) {
            char c = client.read();
            request += c;
            if (c == '\n') break;
        }
    }
    
    // 解析请求
    int ledState = LOW;
    if (request.indexOf("GET /on") >= 0) {
        digitalWrite(LED_BUILTIN, HIGH);
        ledState = HIGH;
    } else if (request.indexOf("GET /off") >= 0) {
        digitalWrite(LED_BUILTIN, LOW);
        ledState = LOW;
    }
    
    // 发送 HTML 页面
    client.println("HTTP/1.1 200 OK");
    client.println("Content-Type: text/html; charset=utf-8");
    client.println("Connection: close");
    client.println();
    client.println("<!DOCTYPE html><html><head><meta charset='UTF-8'>");
    client.println("<meta name='viewport' content='width=device-width,initial-scale=1'>");
    client.println("<title>Nano 33 IoT</title></head><body>");
    client.println("<h1>Nano 33 IoT Web Server</h1>");
    client.printf("<p>LED: <strong>%s</strong></p>", ledState ? "ON" : "OFF");
    client.println("<p><a href='/on'><button>ON</button></a> ");
    client.println("<a href='/off'><button>OFF</button></a></p>");
    client.println("</body></html>");
    
    delay(10);
    client.stop();
    Serial.println("Client disconnected.");
}
```

> **编译提示**：Arduino IDE → `Tools → Board → Arduino Nano 33 IoT`，需安装 `Arduino SAMD Boards (32-bits ARM Cortex-M0+)`。WiFi 相关需安装 `WiFiNINA` 库。