wolfSSL · dgarske · Jul 8, 2026
diff --git a/src/port/rtl8735b/README.md b/src/port/rtl8735b/README.md
@@ -0,0 +1,73 @@
+# wolfIP on RealTek RTL8735B (AmebaPro2)
+
+wolfIP TCP/IP stack running over the RTL8735B's native 10/100 Ethernet MAC (with its integrated Fast-Ethernet PHY), built inside the RealTek AmebaPro2 FreeRTOS SDK. Two demos, built from the same sources:
+
+1. **Milestone 1** - DHCP client + raw TCP echo server (port 7). Proves the driver and stack.
+2. **Milestone 2** - a wolfSSL TLS 1.2/1.3 client over a real wolfIP socket (add `--tls`).
+
+## How it works
+
+The RTL8735B has a native Ethernet MAC + integrated FEPHY (no external PHY). The vendor SDK exposes a frame-level mbed HAL (`ethernet_init/write/send/receive/read`) that owns the DMA descriptor rings and the D-cache clean/invalidate internally. This port is a thin adapter that binds wolfIP's two driver callbacks onto that HAL - no register-level MAC/DMA/MDIO code:
+
+- wolfIP `send()` -> `ethernet_write()` + `ethernet_send()`
+- wolfIP `poll()` -> `ethernet_receive()` + `ethernet_read()`
+
+The whole stack runs in a single FreeRTOS task, so no wolfIP locking is required. RX is polled (milestone 1/2); the MAC IRQ hook only latches link up/down. The vendor lwIP layer is not used - wolfIP owns the interface.
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `wolfip_rtl8735b.c` / `.h` | wolfIP poll/send driver glue over the mbed Ethernet HAL |
+| `main.c` | App: single task - MAC init, link/DHCP wait, echo server, optional TLS client |
+| `config.h` | wolfIP build config (DHCP, socket counts, static-IP fallback) |
+| `user_settings.h` | wolfSSL config for the TLS client (software crypto, ECDHE-ECDSA/AES-GCM) |
+| `tls_client.c` / `.h` | Board-agnostic wolfIP TLS client (shared with the other ports) |
+| `wolfip_eth.cmake` | SDK build integration (append wolfIP + optional wolfSSL sources) |
+| `wolfip_cycle.sh` | Build -> flash -> read-console helper |
+
+## Build and run
+
+Prerequisites: the AmebaPro2 FreeRTOS SDK (`~/GitHub/ameba-rtos-pro2`), the ASDK 10.3.0 toolchain, and the hardware bench (Pi4 GPIO 21 boot-mode, J-Link nRESET for the CHIP_EN power-on reset, console on `/dev/ttyUSB5`). The system `arm-none-eabi-gcc` will not work - use the ASDK toolchain.
+
+### SDK config
+
+No SDK source edits are required. The non-TrustZone (`ntz`) app build already compiles the mbed Ethernet HAL: `DEVICE_ETHERNET=1` (device.h non-secure branch) and `CONFIG_MII_EN=1` (platform_conf_ntz.h). This port calls that HAL directly, so the vendor `CONFIG_ETHERNET`/lwIP path stays disabled (`CONFIG_ETHERNET=0`) and no lwIP is linked in.
+
+### Hands-free cycle
+
+```bash
+cd ~/GitHub/wolfip/src/port/rtl8735b
+./wolfip_cycle.sh            # milestone 1: DHCP + echo
+./wolfip_cycle.sh --tls      # milestone 2: also build/run the TLS client
+```
+
+### Manual build
+
+```bash
+export PATH=~/ameba-pro2-workspace/asdk/asdk-10.3.0/linux/newlib/bin:$PATH
+P=~/GitHub/ameba-rtos-pro2/project/realtek_amebapro2_v0_example
+mkdir -p $P/component/example/wolfip_eth
+cp main.c user_settings.h wolfip_eth.cmake $P/component/example/wolfip_eth/
+cp main.c $P/src/main.c
+cd $P/GCC-RELEASE && mkdir -p build && cd build
+cmake .. -G"Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=../toolchain.cmake \
+  -DBUILD_FPGA=OFF -DBUILD_PXP=OFF -DEXAMPLE=wolfip_eth \
+  -DWOLFIP_ROOT=~/GitHub/wolfip
+make flash -j8               # -> build/flash_ntz.bin
+~/.claude/skills/amebapro2-flash/amebapro2_flash.sh build/flash_ntz.bin
+uart-monitor tail GENERIC_UART_ttyUSB5
+```
+
+For the TLS build add `-DWOLFIP_ENABLE_TLS=ON -DWOLFSSL_ROOT=~/GitHub/wolfssl`.
+
+## Verify
+
+- **M1:** the console prints the MAC, `Link up`, and `DHCP bound: ip=...`. From the host: `ping <ip>` and `nc <ip> 7` (whatever you type is echoed back).
+- **M2:** additionally `TLS: connecting to ...` and `TLS: received N bytes` with the server's response. The TLS target defaults to an ECDSA host; override with `-DTLS_TARGET_IP`/`-DTLS_TARGET_HOST`/`-DTLS_TARGET_PORT`. Certificate verification is disabled in the demo (no RTC / CA store).
+
+## Notes / limits
+
+- Certificate validation is off (`WOLFSSL_VERIFY_NONE`) - demo only. Add a CA store and an RTC/`NO_ASN_TIME` removal for production.
+- RX is polled today. An IRQ-driven path (push frames via `wolfIP_recv_ex()` from the RX thread) is a planned follow-up.
+- Descriptor rings are placed in the reserved `__sram_rev_start__` SRAM region and packet buffers in the vendor DMA heap, mirroring the SDK's own `ethernet_mii` driver.
diff --git a/src/port/rtl8735b/config.h b/src/port/rtl8735b/config.h
@@ -0,0 +1,71 @@
+/* config.h
+ *
+ * Copyright (C) 2026 wolfSSL Inc.
+ *
+ * This file is part of wolfIP TCP/IP stack.
+ *
+ * wolfIP is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfIP is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ *
+ * wolfIP build configuration for the RTL8735B (AmebaPro2) port.
+ */
+#ifndef WOLF_CONFIG_H
+#define WOLF_CONFIG_H
+
+#ifndef CONFIG_IPFILTER
+#define CONFIG_IPFILTER         0
+#endif
+
+#define ETHERNET
+#define LINK_MTU                1536
+
+/* Socket configuration. The RTL8735B has ample DDR, but keep the stack's
+ * static footprint modest for the demo. */
+#define MAX_TCPSOCKETS          8
+#define MAX_UDPSOCKETS          2
+#define MAX_ICMPSOCKETS         1
+#define RXBUF_SIZE              (LINK_MTU * 6)
+#define TXBUF_SIZE              (LINK_MTU * 6)
+
+#define MAX_NEIGHBORS           16
+
+#ifndef WOLFIP_MAX_INTERFACES
+#define WOLFIP_MAX_INTERFACES   1
+#endif
+
+#ifndef WOLFIP_ENABLE_FORWARDING
+#define WOLFIP_ENABLE_FORWARDING 0
+#endif
+
+#ifndef WOLFIP_ENABLE_LOOPBACK
+#define WOLFIP_ENABLE_LOOPBACK  0
+#endif
+
+#ifndef WOLFIP_ENABLE_DHCP
+#define WOLFIP_ENABLE_DHCP      1
+#endif
+
+/* Static IP fallback (used when DHCP is disabled or times out). */
+#define WOLFIP_IP               "192.168.1.100"
+#define WOLFIP_NETMASK          "255.255.255.0"
+#define WOLFIP_GW               "192.168.1.1"
+#define WOLFIP_STATIC_DNS_IP    "8.8.8.8"
+
+#if WOLFIP_ENABLE_DHCP
+#define DHCP
+#define DHCP_DISCOVER_RETRIES 6
+#define DHCP_REQUEST_RETRIES  6
+#endif
+
+#endif /* WOLF_CONFIG_H */