feat: add WIZnet W5500-EVB-Pico2 + E22P-868M30S variant

variants/rp2350/diy/wiznet_5500_evb_pico2_e22p/README.md

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+# WIZnet W5500-EVB-Pico2 + E22P-868M30S — Meshtastic Variant
+
+Meshtastic support for the **WIZnet W5500-EVB-Pico2**, a Raspberry Pi Pico 2 development board with an **integrated W5500 Ethernet PHY** on SPI0, paired with an external **EBYTE E22P-868M30S** LoRa module on SPI1.
+
+This variant is hardware-twin of [`pico2_w5500_e22`](../diy/pico2_w5500_e22/) (same LoRa pinout, same W5500 pin mapping) but targets the WIZnet PCB rather than a standalone Pico 2 + external W5500 module. The two key differences are:
+
+|              | `pico2_w5500_e22`                      | `wiznet_5500_evb_pico2_e22p`             |
+| ------------ | -------------------------------------- | ---------------------------------------- |
+| Board target | `rpipico2` (4 MB flash)                | `wiznet_5500_evb_pico2` (**2 MB flash**) |
+| W5500 PHY    | External breakout module (you wire it) | Integrated on the PCB (hard-wired)       |
+
+> ⚠️ Flashing a W5500-EVB-Pico2 with the `pico2_w5500_e22` env builds for a 4 MB flash target and can silently overflow the 2 MB available on the WIZnet PCB. Use this variant for the WIZnet board.
+
+The LoRa wiring and `variant.h` are shared with `diy/pico2_w5500_e22` via `-I variants/rp2350/diy/pico2_w5500_e22` — there is no duplicated pinout file.
+
+---
+
+## Required Hardware
+
+| Component | Model                  | Notes                                                                          |
+| --------- | ---------------------- | ------------------------------------------------------------------------------ |
+| Board     | WIZnet W5500-EVB-Pico2 | RP2350 @ 150 MHz, 512 KB RAM, **2 MB flash**, on-board W5500                   |
+| LoRa      | EBYTE E22P-868M30S     | SX1262 + 30 dBm PA, 868 MHz (Europe band); RFEN combines LNA + PA enable lines |
+
+The W5500-EVB-Pico2 carries a smaller Q-SPI flash (2 MB) than a stock Pi Pico 2 (4 MB). The board target `wiznet_5500_evb_pico2` selects the correct flash size so the linker fails fast if the image overflows, instead of producing a UF2 that gets truncated when flashed to the device.
+
+---
+
+## Pinout
+
+### System pins (W5500-EVB-Pico2, fixed by the PCB)
+
+| GPIO | Function                                |
+| ---- | --------------------------------------- |
+| GP24 | VBUS sense — HIGH when USB is connected |
+| GP25 | User LED (heartbeat)                    |
+| GP29 | ADC3 — VSYS/3, measures supply voltage  |
+
+### W5500 Ethernet (SPI0, on-board)
+
+| W5500 signal | RP2350 GPIO |
+| ------------ | ----------- |
+| MISO         | GP16        |
+| CS / SCS     | GP17        |
+| SCK          | GP18        |
+| MOSI         | GP19        |
+| RST          | GP20        |
+| INT          | GP21        |
+| VCC          | 3.3V        |
+| GND          | GND         |
+
+> All Ethernet pins are wired by the PCB — nothing to solder. SPI0 is reserved for the W5500.
+
+### E22P-868M30S LoRa (SPI1, external)
+
+| E22P signal | RP2350 GPIO | Notes                                             |
+| ----------- | ----------- | ------------------------------------------------- |
+| SCK         | GP10        | SPI1 clock                                        |
+| MOSI        | GP11        | SPI1 TX                                           |
+| MISO        | GP12        | SPI1 RX                                           |
+| NSS / CS    | GP13        | Chip select                                       |
+| RESET       | GP15        | Active LOW reset                                  |
+| DIO1        | GP14        | IRQ interrupt                                     |
+| BUSY        | GP2         | Module busy indicator                             |
+| RFEN        | GP3         | Combined LNA + PA enable — held HIGH at all times |
+| TXEN        | ← DIO2      | Bridge on the module (see below)                  |
+| VCC         | 3.3V        | Add a 100 µF capacitor close to the module        |
+| GND         | GND         | —                                                 |
+
+---
+
+## E22**P** vs E22 — what changed
+
+The E22**P**-868M30**S** is the newer revision of EBYTE's 30 dBm 868 MHz module. The pinout is interchangeable with the E22-900M30S but the RF switch control differs:
+
+- On the older E22-900M30S, **RXEN** enables the LNA and **TXEN** enables the PA (two separate pins).
+- On the E22**P**-868M30**S**, both functions are merged into a single **RFEN** pin acting as a global RF enable. RFEN must be held HIGH whenever the radio is active — both during RX and TX.
+
+The firmware drives this with `SX126X_ANT_SW 3`, which sets GP3 (RFEN) HIGH once at boot and leaves it there. TXEN switching during transmit is still handled by the on-module DIO2 → TXEN bridge (see below).
+
+---
+
+## Special wiring: DIO2 → TXEN bridge on the E22P module
+
+The E22P-868M30S does **not** connect DIO2 to the TXEN pin of its PA internally. They must be bridged with a short wire or solder bridge **on the module itself**:
+
+```text
+E22P DIO2 pin  ──┐
+                 ├── wire / solder bridge on the module
+E22P TXEN pin  ──┘
+```
+
+With this bridge in place, `SX126X_DIO2_AS_RF_SWITCH` causes the SX1262 to drive DIO2 HIGH automatically during TX, enabling the PA without needing an RP2350 GPIO for TXEN.
+
+**Without this bridge the module will not transmit.**
+
+---
+
+## Build
+
+```bash
+pio run -e wiznet_5500_evb_pico2_e22p
+```
+
+### Flash — BOOTSEL mode
+
+1. Hold the **BOOTSEL** button on the W5500-EVB-Pico2.
+2. Connect USB to the PC — it appears as a `RPI-RP2` storage drive.
+3. Copy the `.uf2` file:
+
+```text
+.pio/build/wiznet_5500_evb_pico2_e22p/firmware-wiznet_5500_evb_pico2_e22p-*.uf2
+```
+
+Or directly with picotool:
+
+```bash
+pio run -e wiznet_5500_evb_pico2_e22p -t upload
+```
+
+---
+
+## Network usage
+
+This board uses Ethernet (no Wi-Fi). From the Meshtastic app:
+
+- **Enable Ethernet** under `Config → Network → Ethernet Enabled`
+- **DHCP** by default; static IP can also be configured
+
+Services available once connected:
+
+| Service | Details                     |
+| ------- | --------------------------- |
+| NTP     | Time synchronization        |
+| MQTT    | Messages to external broker |
+| API     | TCP socket on port 4403     |
+| Syslog  | Remote logging (optional)   |
+
+---
+
+## Technical notes
+
+### LoRa — RF control
+
+| Define                         | Effect                                                      |
+| ------------------------------ | ----------------------------------------------------------- |
+| `SX126X_ANT_SW 3`              | GP3 (RFEN) driven HIGH at init and never toggled again      |
+| `SX126X_DIO2_AS_RF_SWITCH`     | SX1262 drives DIO2 HIGH during TX → enables TXEN via bridge |
+| `SX126X_DIO3_TCXO_VOLTAGE 1.8` | E22P TCXO controlled by DIO3                                |
+| `-D EBYTE_E22_900M30S`         | Sets `TX_GAIN_LORA=7`, max power 22 dBm                     |
+
+### Ethernet
+
+- Library: `arduino-libraries/Ethernet@^2.0.2` (supports W5100/W5200/W5500 auto-detection).
+- SPI0 is explicitly initialized with pins GP16/18/19 before `Ethernet.init()`.
+- DHCP timeout is set to 10 s (instead of the default 60 s) to avoid blocking LoRa startup.
+
+### HW_VENDOR
+
+Mapped to `meshtastic_HardwareModel_PRIVATE_HW` — no dedicated model exists in the Meshtastic protobuf for this hardware combination.

variants/rp2350/diy/wiznet_5500_evb_pico2_e22p/platformio.ini

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+[env:wiznet_5500_evb_pico2_e22p]
+extends = rp2350_base
+board = wiznet_5500_evb_pico2
+board_level = community
+upload_protocol = picotool
+
+# Reuses the variant.h from variants/rp2350/diy/pico2_w5500_e22 — same LoRa
+# pinout, same W5500 pin mapping. The only differences vs pico2_w5500_e22 are
+# the board target (this PCB has 2 MB flash instead of 4 MB) and the W5500
+# being soldered on-board instead of an external module.
+build_flags =
+  ${rp2350_base.build_flags}
+  -ULED_BUILTIN                   # avoid "LED_BUILTIN redefined" warnings from framework common.h
+  -I variants/rp2350/diy/pico2_w5500_e22
+  -D HW_SPI1_DEVICE
+  -D EBYTE_E22_900M30S            # selects the EBYTE E22(P)-900M30S(S) module config, including TCXO voltage support and TX gain / max power settings
+
+# Re-enable Ethernet and API source paths excluded in rp2350_base
+build_src_filter = ${rp2350_base.build_src_filter} +<mesh/eth/> +<mesh/api/> +<mqtt/>
+
+lib_deps =
+  ${rp2350_base.lib_deps}
+  ${networking_base.lib_deps}
+  ${networking_extra.lib_deps}
+  # Standard WIZnet Ethernet library — supports W5100/W5200/W5500 auto-detect
+  arduino-libraries/Ethernet@^2.0.2
+
+debug_build_flags = ${rp2350_base.build_flags}, -g
+debug_tool = cmsis-dap