🛠 Passerelle domotique : le duo Wi-Fi + H2

Tutorial on architecture: the smart home gateway. Since the H2 does not support Wi-Fi, a Thread/Zigbee gateway to the IP world relies on a duo: a Wi-Fi SoC (ESP32-S3 or ESP32-C6) for IP connectivity and the H2 for 802.15.4 radio. This is exactly the architecture of commercial products — LILYGO T-Panel (S3 + H2 with 4-inch HMI screen), M5Stack Unit Gateway H2 — or the esp-thread-br project (Linux + H2, or S3 + H2). Tutorial: make a DevKitM-1 communicate as a wired Thread router, powered therefore without deep-sleep constraints, with a Wi-Fi controller, then forward events from Zigbee/Thread nodes to a broker. Note that the C6, on the other hand, can handle Matter endpoints and Wi-Fi on its own — but also cannot act as a standalone Thread border router. Points of attention for the H2 in a powered gateway: CHIP_EN never floating, VDD3P3 between 3.0 and 3.6 V, 32.768 kHz crystal populated (DevKitM-1 boards before February 2024 do not have one), and GPIO26/27 reserved for USB debug until the product is validated.