Added Power Saving for room servers

examples/simple_room_server/MyMesh.cpp

@@ -1022,3 +1022,11 @@ void MyMesh::loop() {
   uptime_millis += now - last_millis;
   last_millis = now;
 }
+
+// To check if there is pending work
+bool MyMesh::hasPendingWork() const {
+#if defined(WITH_BRIDGE)
+  if (bridge.isRunning()) return true; // bridge needs WiFi radio, can't sleep
+#endif
+  return _mgr->getOutboundTotal() > 0;
+}

examples/simple_room_server/MyMesh.h

@@ -222,4 +222,7 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   void clearStats() override;
   void handleCommand(uint32_t sender_timestamp, char* command, char* reply);
   void loop();
+
+  // To check if there is pending work
+  bool hasPendingWork() const;
 };

examples/simple_room_server/main.cpp

@@ -18,6 +18,9 @@ void halt() {
 
 static char command[MAX_POST_TEXT_LEN+1];
 
+// For power saving
+unsigned long POWERSAVING_FIRSTSLEEP_SECS = 120; // The first sleep (if enabled) from boot
+
 void setup() {
   Serial.begin(115200);
   delay(1000);
@@ -113,4 +116,14 @@ void loop() {
   ui_task.loop();
 #endif
   rtc_clock.tick();
-}
+
+  if (the_mesh.getNodePrefs()->powersaving_enabled && !the_mesh.hasPendingWork()) {
+#if defined(NRF52_PLATFORM)
+    board.sleep(0); // nrf ignores seconds param, sleeps whenever possible
+#else
+    if (the_mesh.millisHasNowPassed(POWERSAVING_FIRSTSLEEP_SECS * 1000)) { // To check if it is time to sleep
+      board.sleep(30); // Sleep. Wake up after a while or when receiving a LoRa packet
+    }
+#endif
+  }
+}