tcp_client

# TCP Client Example

This example initializes the SPI port layer, configures W5500 through ioLibrary, and runs a TCP client loopback using a non-blocking socket and direct RX buffer access (wiz_recv_data).

**Key points:**
- The socket is opened in non-blocking mode (SF_IO_NONBLOCK) to avoid WDT during connect.
- Data reception does not use the standard recv() API, but instead reads directly from the RX buffer using wiz_recv_data and setSn_CR(Sn_CR_RECV).
- This approach avoids the ioLibrary's non-blocking recv() busy loop issue and prevents WDT resets.

**Note:**
- The application is responsible for checking socket state and RX buffer size before reading.
## Build

```bash
idf.py set-target esp32s3
idf.py build
```

## Configuration

- Server endpoint is configured in `main/main.c`:
  - `EXAMPLE_SERVER_IP`
  - `EXAMPLE_SERVER_PORT`
- SPI host/clock/pins come from:
  - `Component config -> WIZnet TOE Component`

## Run

```bash
idf.py -p <PORT> flash monitor
```

## Test with netcat

On PC (server side):

```bash
nc -l 5000
```

Expected behavior:

1. ESP initializes SPI and W5500
2. Network info is applied
3. TCP client connects to server (non-blocking, WDT-safe)
4. Loopback handler echoes received payload using direct RX buffer access