readme

README.md

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+# lwIP Ethernet Driver for CH32V208
+
+This is a simple ethernetif.c driver to get lwIP working on the WCH CH32V208 MCU using the ch32fun lib.  
+It uses the chip's internal 10Mbps Ethernet MAC. The MAC address is pulled from the chip's 6-byte unique ID.
+
+The provided main.c is an example that starts up, gets an IP address via DHCP, and runs a small HTTP server.
+
+## Usage
+
+1.  Initialize lwIP and add the network interface.
+2.  Poll the driver and service lwIP's timers in your main loop.
+
+```c
+netif_add(&g_netif, &ipaddr, &netmask, &gw, NULL, &ethernetif_init, &ethernet_input);
+netif_set_default(&g_netif);
+netif_set_up(&g_netif);
+dhcp_start(&g_netif);
+
+while (1) {
+  // poll for incoming packets
+  ethernetif_input(&g_netif);
+
+  // handle lwIP timers (for TCP, DHCP, etc.)
+  sys_check_timeouts();
+
+  // poll link for link up/down cb
+  ethernetif_link_poll(&g_netif);
+}
+```
+
+## Impl note
+
+This driver is kinda functional but not optimized at all
+
+-   **Packet RX:** This is done by polling. You must call `ethernetif_input()` continuously in your main loop to check for and process incoming packets
+-   **Packet TX:** Kicking off a transmission is a blocking copy, but freeing the transmit buffer on completion is handled by the `ETH_IRQHandler` ISR