examples/device/net_lwip_webserver/README.md - third_party/github/hathach/tinyusb - Git at Google

 # Network Web Server (lwIP)

 A USB virtual network adapter that runs a small lwIP stack on the device, serving DHCP, DNS, and a web page over USB.

 ## What it does

 - Brings up a USB network interface. Depending on the target MCU the build is either CDC-NCM (the default for most MCUs) or a dual RNDIS + CDC-ECM device that offers two configurations and lets the host pick its preferred one (Windows uses RNDIS, macOS uses CDC-ECM, Linux works with either). The NCM build also ships a BOS / Microsoft OS 2.0 descriptor so Windows auto-loads its NCM driver.
 - The device takes IP address 192.168.7.1 and runs a DHCP server (handing out 192.168.7.2–192.168.7.4), a DNS server (resolves `tiny.usb`), and an HTTP server.
 - Pressing the board button toggles the network link state (up/down) to simulate an Ethernet cable being unplugged/plugged.
 - On higher-RAM MCUs it also starts an iperf TCP server for throughput testing.
 - Blinks the board LED to indicate USB state (not mounted / mounted / suspended).

 ## Requirements

 - Depends on the lwIP TCP/IP stack, fetched as a dependency (e.g. `python3 tools/get_deps.py`).

 ## USB Descriptors

 | Interface | Class driver |
 |-----------|--------------|
 | 0–1 | Network (CDC-NCM, or CDC-ECM/RNDIS) |

 ## Configuration

 Notable `tusb_config.h` settings:

 ```c
 // Network driver selection: NCM is the default; USE_ECM defaults to 0 but is
 // forced to 1 on some MCUs (LPC15xx/40xx/51uxx/54, SAMD21/SAML2x, STM32F0/F1).
 #define CFG_TUD_ECM_RNDIS     USE_ECM            // 0 by default -> ECM/RNDIS off
 #define CFG_TUD_NCM           (1 - CFG_TUD_ECM_RNDIS)  // 1 by default -> NCM on

 // NCM tuning (see ncm.h for performance notes)
 #define CFG_TUD_NCM_IN_NTB_MAX_SIZE  2048
 #define CFG_TUD_NCM_OUT_NTB_MAX_SIZE 4096        // 2048 on low-RAM MCUs
 #define CFG_TUD_NCM_OUT_NTB_N        1
 #define CFG_TUD_NCM_IN_NTB_N         1
 ```

 ## Building

 CMake:

 ```bash
 mkdir build && cd build
 cmake -DBOARD=raspberry_pi_pico ..
 cmake --build .
 ```

 Make:

 ```bash
 make BOARD=raspberry_pi_pico all
 ```

 ## Try it

 A new USB network interface appears on the host. It is normally assigned an address in 192.168.7.x by the device's DHCP server (otherwise give the host NIC a static 192.168.7.x address), then browse to http://192.168.7.1 to load the served web page.
	# Network Web Server (lwIP)

	A USB virtual network adapter that runs a small lwIP stack on the device, serving DHCP, DNS, and a web page over USB.

	## What it does

	- Brings up a USB network interface. Depending on the target MCU the build is either CDC-NCM (the default for most MCUs) or a dual RNDIS + CDC-ECM device that offers two configurations and lets the host pick its preferred one (Windows uses RNDIS, macOS uses CDC-ECM, Linux works with either). The NCM build also ships a BOS / Microsoft OS 2.0 descriptor so Windows auto-loads its NCM driver.
	- The device takes IP address 192.168.7.1 and runs a DHCP server (handing out 192.168.7.2–192.168.7.4), a DNS server (resolves `tiny.usb`), and an HTTP server.
	- Pressing the board button toggles the network link state (up/down) to simulate an Ethernet cable being unplugged/plugged.
	- On higher-RAM MCUs it also starts an iperf TCP server for throughput testing.
	- Blinks the board LED to indicate USB state (not mounted / mounted / suspended).

	## Requirements

	- Depends on the lwIP TCP/IP stack, fetched as a dependency (e.g. `python3 tools/get_deps.py`).

	## USB Descriptors

	\| Interface \| Class driver \|
	\|-----------\|--------------\|
	\| 0–1 \| Network (CDC-NCM, or CDC-ECM/RNDIS) \|

	## Configuration

	Notable `tusb_config.h` settings:

	```c
	// Network driver selection: NCM is the default; USE_ECM defaults to 0 but is
	// forced to 1 on some MCUs (LPC15xx/40xx/51uxx/54, SAMD21/SAML2x, STM32F0/F1).
	#define CFG_TUD_ECM_RNDIS USE_ECM // 0 by default -> ECM/RNDIS off
	#define CFG_TUD_NCM (1 - CFG_TUD_ECM_RNDIS) // 1 by default -> NCM on

	// NCM tuning (see ncm.h for performance notes)
	#define CFG_TUD_NCM_IN_NTB_MAX_SIZE 2048
	#define CFG_TUD_NCM_OUT_NTB_MAX_SIZE 4096 // 2048 on low-RAM MCUs
	#define CFG_TUD_NCM_OUT_NTB_N 1
	#define CFG_TUD_NCM_IN_NTB_N 1
	```

	## Building

	CMake:

	```bash
	mkdir build && cd build
	cmake -DBOARD=raspberry_pi_pico ..
	cmake --build .
	```

	Make:

	```bash
	make BOARD=raspberry_pi_pico all
	```

	## Try it

	A new USB network interface appears on the host. It is normally assigned an address in 192.168.7.x by the device's DHCP server (otherwise give the host NIC a static 192.168.7.x address), then browse to http://192.168.7.1 to load the served web page.