Add maintenance mode and board status indicators

Provide BOOT-triggered USB CDC maintenance mode for file updates, plus
onboard LED activity flashes and enhanced display status information.

main.py

@@ -4,8 +4,10 @@ import network
 import time
 import urandom
 
+import maintenance
 from display import StatusDisplay
 from hid import get_hid
+from led import ActivityLed
 from settings import load, save
 from web import WebServer
 
@@ -51,13 +53,39 @@ def ip_address(wlan):
         return wlan.ifconfig()[0]
 
 
+def mac_address(wlan):
+    """Return the station interface MAC address in conventional display form."""
+    try:
+        mac = wlan.config("mac")
+    except (AttributeError, OSError, ValueError):
+        return None
+    if not isinstance(mac, (bytes, bytearray)) or len(mac) != 6:
+        return None
+    return "%02X:%02X:%02X:%02X:%02X:%02X" % tuple(mac)
+
+
+def wifi_rssi(wlan):
+    """Return RSSI in dBm when the current ESP32 port exposes it."""
+    if not wlan.isconnected():
+        return None
+    try:
+        return wlan.status("rssi")
+    except (AttributeError, OSError, ValueError):
+        return None
+
 
 def main():
+    # boot.py leaves USB CDC enabled in maintenance mode; do not activate Wi-Fi,
+    # the display, web server, or injection scheduler in that local service mode.
+    if maintenance.active:
+        return
+
     settings = load()
     display = None
     if settings["display_enabled"]:
         display = StatusDisplay()
     hid = get_hid()
+    activity_led = ActivityLed()
     wlan = connect_wifi(settings)
     volume_requests = []
 
@@ -76,9 +104,14 @@ def main():
     # connect_wifi() already started the first attempt; do not call connect()
     # again while the ESP32 station is still in STAT_CONNECTING state.
     next_wifi_retry = time.ticks_add(now, 10000)
+    next_display_network_refresh = now
+    display_address = None
+    display_mac = None
+    display_rssi = None
 
     while True:
         now = time.ticks_ms()
+        activity_led.tick(now)
         server.poll()
 
         # Reconnect without blocking injections or the web server indefinitely.
@@ -89,8 +122,17 @@ def main():
             next_wifi_retry = time.ticks_add(now, 10000)
 
         if display is not None:
-            address = ip_address(wlan) if wlan.isconnected() else None
-            display.tick(now, settings["wifi_ssid"], address)
+            # The display itself is frame-driven; query WLAN state only once per
+            # second rather than for every 25 ms application-loop iteration.
+            if time.ticks_diff(now, next_display_network_refresh) >= 0:
+                display_address = ip_address(wlan) if wlan.isconnected() else None
+                display_mac = mac_address(wlan)
+                display_rssi = wifi_rssi(wlan)
+                next_display_network_refresh = time.ticks_add(now, 1000)
+            display.tick(
+                now, settings["wifi_ssid"], display_address, display_mac,
+                display_rssi, maintenance.button_pressed()
+            )
 
 
         if release_at is not None and time.ticks_diff(now, release_at) >= 0:
@@ -105,11 +147,13 @@ def main():
                 hid.press_volume_up()
             else:
                 hid.press_volume_down()
+            activity_led.pulse(0, 0, 255, now)
             consumer_release_at = time.ticks_add(now, KEY_HOLD_MS)
 
         if (settings["enabled"] and settings["return_enabled"] and
                 release_at is None and time.ticks_diff(now, next_return) >= 0):
             hid.press_return()
+            activity_led.pulse(255, 0, 0, now)
             release_at = time.ticks_add(now, KEY_HOLD_MS)
             next_return = choose_due(
                 now, settings["return_min_seconds"], settings["return_max_seconds"]
@@ -124,6 +168,7 @@ def main():
             if x == 0 and y == 0:
                 x = distance
             hid.move(x, y)
+            activity_led.pulse(0, 255, 0, now)
             next_mouse = choose_due(
                 now, settings["mouse_min_seconds"], settings["mouse_max_seconds"]
             )