[libretiny] Flag the LN882H SDK default MAC (#20175)

esphome/components/libretiny/lt_component.cpp

@@ -2,6 +2,9 @@
 
 #ifdef USE_LIBRETINY
 
+#include <cstring>
+
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 namespace esphome::libretiny {
@@ -18,6 +21,17 @@ void LTComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "  Optimization: -Os, SDK: -O" STRINGIFY_MACRO(__OPTIMIZE_LEVEL__));
 #endif
 
+#if defined(USE_LN882X) && defined(USE_WIFI)
+  // The SDK falls back to this MAC when the board layout's KV store holds none.
+  static constexpr uint8_t SDK_DEFAULT_MAC[MAC_ADDRESS_SIZE] = {0x00, 0x50, 0xC2, 0x5E, 0x10, 0x88};
+  uint8_t mac[MAC_ADDRESS_SIZE];
+  get_mac_address_raw(mac);
+  if (memcmp(mac, SDK_DEFAULT_MAC, MAC_ADDRESS_SIZE) == 0) {
+    ESP_LOGE(TAG, "MAC is the LN882H SDK default 00:50:C2:5E:10:88; only one device with it can be on a network. "
+                  "On a Tuya module, set board: to its Tuya board (e.g. wl2s, wl2h-u) and flash over serial");
+  }
+#endif
+
 #ifdef USE_TEXT_SENSOR
   if (this->version_ != nullptr) {
     this->version_->publish_state(&LT_BANNER_STR[10]);