lower dust sensor working period

src/main.cpp

@@ -159,7 +159,7 @@ void ICACHE_FLASH_ATTR sendValues() {
 //  sds.wakeup(); delay(30000); // working 30 seconds
   PmResult pm = sds.queryPm();
   bool sds_updated = false;
-  if(pm.isOk()) {
+  if(pm.isOk() && (pm.pm25 != sd.p25 || pm.pm10 != sd.p10)) {
     sd.p25 = pm.pm25;
     sd.p10 = pm.pm10;
     sds_updated = true;
@@ -390,7 +390,7 @@ void setup() {
   //wifi_status_led_uninstall();
 
   sds.begin();
-  sds.setCustomWorkingPeriod(5);  // sensor sends data every 5 minutes
+  sds.setCustomWorkingPeriod(15);  // sensor sends data every 15 minutes
   sds.setQueryReportingMode();  // ensures sensor is in 'query' reporting mode
 
   Wire.begin(BMP_SDA, BMP_SCL);

src/main.h

@@ -7,6 +7,6 @@
   #define DEBUG_MSG(...)
 #endif
 
-#define FW_VERSION 20
+#define FW_VERSION 21
 
 #endif /* _MAIN_H */