Reach a server

HTTP Client to the cloud

Device-side GET/POST. Fits REST backends.

Reach a server Call a cloud API ESP32 Wi-Fi parts

Official path: examples/protocols/esp_http_client

01 Overview

Demonstrates ESP32 as an HTTP client: sending requests, parsing status codes, and reading response bodies.

Ideal for REST API integration, firmware version checks, and simple sensor data reporting.

Not suitable for real-time push from server; use MQTT or WebSocket instead.

Supports both HTTP and HTTPS, but HTTPS requires more resources—plan flash and RAM accordingly.

Built on the esp_http_client component, offering both synchronous and asynchronous modes.

Module choice: Any Wi-Fi capable ESP32 module, e.g., ESP32-WROOM-32.
Power: Ensure stable supply; Wi-Fi TX current spikes up to 500mA—leave margin.
Flash size: HTTPS needs certificate storage; at least 4MB recommended.
RAM: TLS handshake and library overhead consume RAM; consider PSRAM or optimize.
Antenna: Keep antenna area clear of metal for reliable signal.
Connectors: Reserve GPIOs and power pins for external sensors if needed.
Debug: Keep UART0 for logs to ease troubleshooting.

1. Initialize NVS, Wi-Fi, and wait for GOT_IP event.

2. Create HTTP client instance, configure URL, method, timeout, and certificates.

3. Set request headers (e.g., Content-Type) and body for POST.

4. Perform request; handle response headers and data in event handler.

5. Parse status code and body; distinguish DNS, TLS, and HTTP errors.

6. For HTTPS, use esp_crt_bundle or custom certs; update periodically.

7. Implement retry with exponential backoff to avoid server overload.

8. Run requests in a separate task to avoid blocking the main loop.

中文

连上服务器

设备主动 GET/POST。对接 REST 云或自己的后台。

连上服务器访问云接口 ESP32 Wi-Fi parts

官方路径: examples/protocols/esp_http_client

演示 ESP32 作为 HTTP 客户端：发起请求、解析状态码、读取响应体。

适用于 REST API 对接、固件版本检查、传感器数据上报等场景。

不适用于需要服务器主动推送的实时通信，应改用 MQTT 或 WebSocket。

支持 HTTP 和 HTTPS，但 HTTPS 需要更多资源，选型时注意 Flash 和 RAM 余量。

示例代码基于 esp_http_client 组件，提供同步和异步两种模式。

1. 初始化 NVS、Wi-Fi 并等待 GOT_IP 事件。

2. 创建 HTTP 客户端实例，配置 URL、方法、超时、证书等。

3. 设置请求头（如 Content-Type）和请求体（POST 时）。

4. 执行请求，在事件处理器中接收响应头和数据。

5. 解析状态码和响应体，区分 DNS 错误、TLS 错误和 HTTP 错误。

6. 对于 HTTPS，使用 esp_crt_bundle 或自定义证书，并定期更新。

7. 实现重试和退避逻辑，避免频繁请求导致服务器压力。

8. 在独立任务中执行请求，避免阻塞主控制循环。