sds custom period

src/main.cpp

@@ -232,7 +232,15 @@ void setup()
   }
 
   sds.begin();
-  sds_active = true; // ToDo
+
+  FirmwareVersionResult sds_fw = sds.queryFirmwareVersion();
+  if (sds_fw.isOk()) {
+    sds_active = true;
+    sds.setActiveReportingMode();  // ensures sensor is in 'active' reporting mode
+    sds.setCustomWorkingPeriod(5); // sensor sends data every 3 minutes
+  } else {
+    Serial.println("Failed to communicate with SDS011 sensor, check wiring?");
+  }
 
   display.clearScreen();
   display.refresh();