Load WIFI_SSID and WIFI_PASSWORD from environment (#274)

Fixes #273

Author: peterharperuk

pico_w/CMakeLists.txt

@@ -4,6 +4,17 @@ if (PICO_CYW43_SUPPORTED) # set by PICO_BOARD=pico_w
     if (NOT TARGET pico_cyw43_arch)
         message("Skipping Pico W examples as support is not available")
     else()
+
+        if (DEFINED ENV{WIFI_SSID} AND (NOT WIFI_SSID))
+            set(WIFI_SSID $ENV{WIFI_SSID})
+            message("Using WIFI_SSID from environment ('${WIFI_SSID}')")
+        endif()
+
+        if (DEFINED ENV{WIFI_PASSWORD} AND (NOT WIFI_PASSWORD))
+            set(WIFI_PASSWORD $ENV{WIFI_PASSWORD})
+            message("Using WIFI_PASSWORD from environment")
+        endif()
+
         set(WIFI_SSID "${WIFI_SSID}" CACHE INTERNAL "WiFi SSID for examples")
         set(WIFI_PASSWORD "${WIFI_PASSWORD}" CACHE INTERNAL "WiFi password for examples")