diff --git a/.gitignore b/.gitignore
index 66fc7a3..1c7318d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,4 @@
 .pio/
+.vscode/c_cpp_properties.json
+.gitignore
+**/DS.store
\ No newline at end of file
diff --git a/CO2_sensor.cpp b/CO2_sensor.cpp
index bb21c8b..2427666 100644
--- a/CO2_sensor.cpp
+++ b/CO2_sensor.cpp
@@ -42,22 +42,32 @@ void initCO2sensor(void)
 void handleCO2sensor(void)
 {
     uint32_t currentmillis = millis();
-    if ((currentmillis - CO2_lastUpdate > (g_pms_report_period * 1000)) || (!CO2_lastUpdate) && (scd30.dataReady()))
+    if ((currentmillis - CO2_lastUpdate > (g_pms_report_period * 1000)) || (!CO2_lastUpdate) )
     {
+        
         if (!scd30.read())
         {
             Serial.println("SCD30: read error!");
             return;
         }
 
-        SCD30_temperature.set(uint32_t(scd30.temperature));
-        SCD30_Humidity.set(uint32_t(scd30.relative_humidity));
-        SCD30_CO2.set(uint32_t(scd30.CO2));
+        if(!scd30.dataReady())
+        {
+            return;
+        }
+        else
+        {
+            SCD30_temperature.set(uint32_t(scd30.temperature));
+            SCD30_Humidity.set(uint32_t(scd30.relative_humidity));
+            SCD30_CO2.set(uint32_t(scd30.CO2));
 
-        SCD30_temperature.publish();
-        SCD30_Humidity.publish();
-        SCD30_CO2.publish();
+            SCD30_temperature.publish();
+            SCD30_Humidity.publish();
+            SCD30_CO2.publish();
+            CO2_lastUpdate = currentmillis;
+        }
+ 
 
-        CO2_lastUpdate = currentmillis;
+        
     }
 }
\ No newline at end of file
diff --git a/VOC_sensor.cpp b/VOC_sensor.cpp
index dfc3b5f..a83223f 100644
--- a/VOC_sensor.cpp
+++ b/VOC_sensor.cpp
@@ -4,14 +4,15 @@ Adafruit_SGP30 sgp;
 uint8_t VOC_samples = 3600 / g_pms_report_period;
 #define VOC_MIN 0
 #define VOC_MAX 10000
+#define VOC_RAW_MAX 30000
 #define VOC_INTERVAL 120000 //ms
 
 uint32_t lastVOCtime = 0;
 //sensors
 AQSSensor SGP30_tvoc("TVOC", SGP30_TVOC, "ppb", device_name, VOC_samples, VOC_MIN, VOC_MAX);
 AQSSensor SGP30_eco2("eCO2", SGP30_eCO2, "ppm", device_name, VOC_samples, VOC_MIN, VOC_MAX);
-AQSSensor SGP30_rawh2("Raw_H2", SGP30_rawH2, "#", device_name, VOC_samples, VOC_MIN, VOC_MAX);
-AQSSensor SGP30_rawethanol("Raw_Ethanol", SGP30_rawEthanol, "#", device_name, VOC_samples, VOC_MIN, VOC_MAX);
+AQSSensor SGP30_rawh2("Raw_H2", SGP30_rawH2, "#", device_name, VOC_samples, VOC_MIN, VOC_RAW_MAX);
+AQSSensor SGP30_rawethanol("Raw_Ethanol", SGP30_rawEthanol, "#", device_name, VOC_samples, VOC_MIN, VOC_RAW_MAX);
 
 void initVOCsensor(void)
 {
@@ -31,7 +32,7 @@ void initVOCsensor(void)
 
     sgp.IAQmeasure();
     sgp.IAQmeasureRaw();
-    
+
     Serial.println("VOCSensor: Init OK");
   }
 }
@@ -50,7 +51,7 @@ void handleVOCsensor(void)
     SGP30_eco2.set(sgp.eCO2);
 
     SGP30_tvoc.publish();
-SGP30_eco2.publish();
+    SGP30_eco2.publish();
 
     if (!sgp.IAQmeasureRaw())
     {
diff --git a/button.h b/button.h
index 9c684f8..de32615 100644
--- a/button.h
+++ b/button.h
@@ -2,6 +2,7 @@
 
 #include "Arduino.h"
 #include "config.h"
+#include "lcd.h"
 
 void initButtons( void );
 void handleButtons( void );
\ No newline at end of file
diff --git a/buttons.cpp b/buttons.cpp
index fc9a552..1b6dd9a 100644
--- a/buttons.cpp
+++ b/buttons.cpp
@@ -27,6 +27,7 @@ void handleButtons(void)
       return;
     }
     Serial.println("Button pressed");
+    backlightRefresh();
     // Increment display state
     g_last_debounce_time = millis();
   }
diff --git a/config.h b/config.h
index 60de90f..e555cf0 100644
--- a/config.h
+++ b/config.h
@@ -28,6 +28,11 @@
 /* ----------------- Hardware-specific Config ---------------------- */
 /* Mode button connection (momentary between this pin and GND) */
 #define MODE_BUTTON_PIN    0
+#define TFT_BL            4            // LED back-light control pin
+#define TFT_BACKLIGHT_ON HIGH  // Level to turn ON back-light (HIGH or LOW)
+#define TFT_BL_PWMCHANNEL  1
+#define TFT_BL_FREQ        5000
+#define TFT_BL_BITS        8
 
 /* I2C */
 #define I2C_SDA_PIN       21
diff --git a/esp_ota.cpp b/esp_ota.cpp
new file mode 100644
index 0000000..c9fbbd2
--- /dev/null
+++ b/esp_ota.cpp
@@ -0,0 +1,46 @@
+#include "esp_ota.h"
+
+void initEspOta(void)
+{
+  Serial.println("ESPOTA: init");
+  ArduinoOTA
+    .onStart([]() {
+      String type;
+      if (ArduinoOTA.getCommand() == U_FLASH)
+        type = "sketch";
+      else // U_SPIFFS
+        type = "filesystem";
+
+      // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
+      Serial.println("ESPOTA: Start updating " + type);
+      ProgressbarVisible(true);
+      ledcWrite(TFT_BL_PWMCHANNEL, 64);
+    })
+    .onEnd([]() {
+      Serial.println("\nESPOTA: End");
+    })
+    .onProgress([](unsigned int progress, unsigned int total) {
+      Serial.printf("ESPOTA: Progress: %u%%\r", (progress / (total / 100)));
+      setOTAProgress((progress / (total / 100)));
+    })
+    .onError([](ota_error_t error) {
+      Serial.printf("ESPOTA: Error[%u]: ", error);
+      if (error == OTA_AUTH_ERROR) Serial.println("ESPOTA: Auth Failed");
+      else if (error == OTA_BEGIN_ERROR) Serial.println("ESPOTA: Begin Failed");
+      else if (error == OTA_CONNECT_ERROR) Serial.println("ESPOTA: Connect Failed");
+      else if (error == OTA_RECEIVE_ERROR) Serial.println("ESPOTA: Receive Failed");
+      else if (error == OTA_END_ERROR) Serial.println("ESPOTA: End Failed");
+    });
+
+  ArduinoOTA.begin();
+
+  Serial.print("ESPOTA: IP address: ");
+  Serial.println(WiFi.localIP());
+  Serial.println("ESPOTA: init OK");
+
+}
+
+void handleEspOta(void)
+{
+  ArduinoOTA.handle();
+}
\ No newline at end of file
diff --git a/esp_ota.h b/esp_ota.h
new file mode 100644
index 0000000..0266609
--- /dev/null
+++ b/esp_ota.h
@@ -0,0 +1,8 @@
+#pragma once
+
+#include "Arduino.h"
+#include <ArduinoOTA.h>
+#include "lcd.h"
+
+void initEspOta(void);
+void handleEspOta(void);
\ No newline at end of file
diff --git a/lcd.cpp b/lcd.cpp
index 0412d9e..de3a054 100644
--- a/lcd.cpp
+++ b/lcd.cpp
@@ -38,6 +38,7 @@ TFT_eSprite needle = TFT_eSprite(&tft); // Sprite object for needle
 TFT_eSprite spr = TFT_eSprite(&tft);    // Sprite for meter reading
 TFT_eSprite nameSpr = TFT_eSprite(&tft);
 TFT_eSprite unitSpr = TFT_eSprite(&tft);
+TFT_eSprite ProgressBar = TFT_eSprite(&tft);
 
 // Jpeg image array attached to this sketch
 #include "dial.h"
@@ -49,6 +50,7 @@ uint16_t *tft_buffer;
 bool buffer_loaded = false;
 uint16_t spr_width = 0;
 uint16_t name_spr_width = 0;
+bool progessbarActive = false;
 
 void createNeedle(void);
 void plotNeedle(int16_t angle, uint16_t ms_delay);
@@ -69,29 +71,58 @@ bool tft_output(int16_t x, int16_t y, uint16_t w, uint16_t h, uint16_t *bitmap)
   return 1;
 }
 
-// =======================================================================================
-// Setup
-// =======================================================================================
-void initLCD()
+void setBacklight(uint8_t value)
 {
-  Serial.print("InitLCD:");
-  // The byte order can be swapped (set true for TFT_eSPI)
-  TJpgDec.setSwapBytes(true);
+  ledcWrite(TFT_BL_PWMCHANNEL, value);
+}
 
-  // The jpeg decoder must be given the exact name of the rendering function above
-  TJpgDec.setCallback(tft_output);
+void createProgressBar(void)
+{
+  ProgressBar.createSprite(220, 30);
+  ProgressBar.fillSprite(TFT_BLACK);
+  ProgressBar.drawRoundRect(0, 2, 220, 22, 5, TFT_BLUE);
+  ProgressBar.pushSprite(10, 270);
+}
 
-  tft.begin();
-  tft.setRotation(0);
-  tft.fillScreen(TFT_BLACK);
+void ProgressbarVisible(bool visible)
+{
+  progessbarActive = visible;
+  if (!visible)
+  {
+    ProgressBar.fillSprite(TFT_BLACK);
+    ProgressBar.pushSprite(10, 270);
+  }
+}
 
-  pinMode(TFT_BL, OUTPUT);
+void setOTAProgress(uint8_t value)
+{
+  uint16_t progress = map(value, 0, 100, 0, 212);
+  ProgressBar.drawRoundRect(0, 2, 220, 22, 5, TFT_BLUE);
+  ProgressBar.fillRoundRect(4, 5, progress, 15, 3, TFT_BLUE);
+  if (progessbarActive)
+  {
+    ProgressBar.pushSprite(10, 270);
+  }
+}
 
-  // Draw the dial
-  TJpgDec.drawJpg(0, 0, dial, sizeof(dial));
-  tft.drawCircle(DIAL_CENTRE_X, DIAL_CENTRE_Y, NEEDLE_RADIUS - NEEDLE_LENGTH, TFT_DARKGREY);
+void createNameSprite(void)
+{
+  nameSpr.setTextFont(2);
+  name_spr_width = nameSpr.textWidth("---Sensor Name---");
+  nameSpr.createSprite(name_spr_width, nameSpr.fontHeight() * 2 + 2);
+  uint16_t bg_color = tft.readPixel(120, 120); // Get colour from dial centre
 
-  // Load the font and create the Sprite for reporting the value
+  nameSpr.fillSprite(bg_color);
+  nameSpr.setTextColor(TFT_WHITE, bg_color);
+  nameSpr.setTextDatum(MC_DATUM);
+  nameSpr.setTextPadding(name_spr_width);
+  nameSpr.drawString("Sensor Name", name_spr_width / 2, nameSpr.fontHeight() / 2);
+  nameSpr.drawString("Unit", name_spr_width / 2, nameSpr.fontHeight() / 2 * 3 + 2);
+  nameSpr.pushSprite(DIAL_CENTRE_X - name_spr_width / 2, DIAL_CENTRE_Y + 40, 2);
+}
+
+void createValueSprinte(void)
+{
   spr.loadFont(AA_FONT_LARGE);
   spr_width = spr.textWidth("277");
   spr.createSprite(spr_width, spr.fontHeight());
@@ -102,25 +133,45 @@ void initLCD()
   spr.setTextPadding(spr_width);
   spr.drawNumber(0, spr_width / 2, spr.fontHeight() / 2);
   spr.pushSprite(DIAL_CENTRE_X - spr_width / 2, DIAL_CENTRE_Y - spr.fontHeight() / 2);
+}
 
-  // Plot the label text
-  nameSpr.setTextFont(2);
-  name_spr_width = nameSpr.textWidth("---Sensor Name---");
-  nameSpr.createSprite(name_spr_width, nameSpr.fontHeight() * 2 + 2);
-  nameSpr.fillSprite(bg_color);
-  nameSpr.setTextColor(TFT_WHITE, bg_color);
-  nameSpr.setTextDatum(MC_DATUM);
-  nameSpr.setTextPadding(name_spr_width);
-  nameSpr.drawString("Sensor Name", name_spr_width / 2, nameSpr.fontHeight() / 2);
-  nameSpr.drawString("Unit", name_spr_width / 2, nameSpr.fontHeight() / 2 * 3 + 2);  nameSpr.pushSprite(DIAL_CENTRE_X - name_spr_width / 2, DIAL_CENTRE_Y + 40, 2);
-  nameSpr.pushSprite(DIAL_CENTRE_X - name_spr_width / 2, DIAL_CENTRE_Y + 40, 2);
+void createDail(void)
+{
+  TJpgDec.setSwapBytes(true);
+
+  // The jpeg decoder must be given the exact name of the rendering function above
+  TJpgDec.setCallback(tft_output);
+  // Draw the dial
+  TJpgDec.drawJpg(0, 0, dial, sizeof(dial));
+  tft.drawCircle(DIAL_CENTRE_X, DIAL_CENTRE_Y, NEEDLE_RADIUS - NEEDLE_LENGTH, TFT_DARKGREY);
 
   // Define where the needle pivot point is on the TFT before
   // creating the needle so boundary calculation is correct
   tft.setPivot(DIAL_CENTRE_X, DIAL_CENTRE_Y);
+}
 
-  // Create the needle Sprite
+// =======================================================================================
+// Setup
+// =======================================================================================
+void initLCD()
+{
+  Serial.print("InitLCD:");
+  // The byte order can be swapped (set true for TFT_eSPI)
+
+  tft.begin();
+  tft.setRotation(0);
+  tft.fillScreen(TFT_BLACK);
+
+  // Create the Sprites
+  createProgressBar();
+  createDail();
+  createValueSprinte();
   createNeedle();
+  createNameSprite();
+
+  ledcSetup(TFT_BL_PWMCHANNEL, TFT_BL_FREQ, TFT_BL_BITS);
+  ledcAttachPin(TFT_BL, TFT_BL_PWMCHANNEL);
+  ledcWrite(TFT_BL_PWMCHANNEL, 64);
 
   // Reset needle position to 0
   plotNeedle(0, 0, 0);
@@ -150,6 +201,47 @@ uint32_t display_last_update = 0;
 #define MINGUAGE 0
 #define DISPLAY_ROTATE 15 //sec
 
+uint32_t backlightTimeout = 0;
+#define BACKLIGHTTIMEOUT 60000
+#define BACKLIGHTONBRGT 129
+#define BACKLIGHTSTEP 5
+uint8_t backloghtBrightness = BACKLIGHTONBRGT;
+
+void backlightRefresh(void)
+{
+  backlightTimeout = millis();
+}
+
+void handleBacklight(void)
+{
+  uint32_t timeNow = millis();
+  if (!backlightTimeout)
+  {
+    backlightRefresh();
+  }
+  if (timeNow - backlightTimeout > BACKLIGHTTIMEOUT)
+  {
+    if (backloghtBrightness > BACKLIGHTSTEP)
+    {
+      backloghtBrightness -= BACKLIGHTSTEP;
+      Serial.printf("LCD: backlight %d\n", backloghtBrightness);
+    }
+    else
+    {
+      backloghtBrightness = 0;
+    }
+  }
+  else
+  {
+    if (backloghtBrightness < BACKLIGHTONBRGT)
+    {
+      backloghtBrightness += BACKLIGHTSTEP;
+      Serial.printf("LCD: backlight %d", backloghtBrightness);
+    }
+  }
+  ledcWrite(TFT_BL_PWMCHANNEL, backloghtBrightness);
+}
+
 void handleLCD()
 {
   static uint16_t angle;
@@ -226,6 +318,8 @@ void handleLCD()
   nameSpr.drawString(sensor->getName().c_str(), name_spr_width / 2, nameSpr.fontHeight() / 2);
   nameSpr.drawString(sensor->getUnit().c_str(), name_spr_width / 2, nameSpr.fontHeight() / 2 * 3 + 2);
   nameSpr.pushSprite(DIAL_CENTRE_X - name_spr_width / 2, DIAL_CENTRE_Y + 40, 2);
+
+  handleBacklight();
 }
 
 // =======================================================================================
diff --git a/lcd.h b/lcd.h
index d07e80c..671094f 100644
--- a/lcd.h
+++ b/lcd.h
@@ -7,3 +7,7 @@ void initLCD();
 void handleLCD();
 
 void plotNeedle(int16_t angle, uint16_t ms_delay, uint32_t value);
+void setOTAProgress(uint8_t value);
+void ProgressbarVisible(bool visible);
+
+void backlightRefresh(void);
\ No newline at end of file
diff --git a/main.cpp b/main.cpp
index 9c8e6f8..d631d53 100644
--- a/main.cpp
+++ b/main.cpp
@@ -41,6 +41,7 @@
 #include "CO2_sensor.h"
 #include "VOC_sensor.h"
 #include "button.h"
+#include "esp_ota.h"
 
 /*--------------------------- Program ---------------------------------------*/
 /**
@@ -52,17 +53,33 @@ void setup()
   Serial.println();
   Serial.print("Air Quality Sensor starting up, v");
   Serial.println(VERSION);
-
-  digitalWrite(5, false);
-
-  initWifi();
-  initMQTT();
-  initSensor();
-  initParticles();
-  initCO2sensor();
-  initVOCsensor();
+  ProgressbarVisible(true);
   initLCD();
+  setOTAProgress(10);
+
   initButtons();
+  setOTAProgress(20);
+  initWifi();
+  setOTAProgress(30);
+
+  initEspOta();
+  setOTAProgress(40);
+
+  initMQTT();
+  setOTAProgress(50);
+
+  initSensor();
+  setOTAProgress(60);
+
+  initParticles();
+  setOTAProgress(70);
+
+  initCO2sensor();
+  setOTAProgress(80);
+
+  initVOCsensor();
+  setOTAProgress(90);
+  ProgressbarVisible(false);
 }
 
 /**
@@ -77,4 +94,5 @@ void loop()
   handleSensor();
   handleLCD();
   handleMQTT();
+  handleEspOta();
 }
diff --git a/particles.cpp b/particles.cpp
index 8924d4d..1824c0e 100644
--- a/particles.cpp
+++ b/particles.cpp
@@ -12,7 +12,7 @@ char g_command_topic[50];        // MQTT topic for receiving commands
 #define PMS_STATE_READY 2     // Warmed up, ready to give data
 #define PMSMAX          50
 #define PSMMIN          0
-#define PPDMAX          2000
+#define PPDMAX          3000
 uint8_t g_pms_state = PMS_STATE_WAKING_UP;
 
 uint32_t g_pms_state_start = 0;       // Timestamp when PMS state last changed
diff --git a/platformio.ini b/platformio.ini
index 04be749..007b65f 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -33,3 +33,5 @@ lib_deps =
 	${common.lib_deps_builtin}
 	${common.lib_deps}
 	adafruit/Adafruit SGP30 Sensor@^2.0.0
+upload_protocol = espota
+upload_port = 192.168.2.236
diff --git a/sensor.h b/sensor.h
index 7573315..1f2d5ae 100644
--- a/sensor.h
+++ b/sensor.h
@@ -42,6 +42,7 @@ class AQSSensor
     bool _publish = false;
     const uint32_t _scaleMin;
     const uint32_t _scaleMax;
+    bool _valid;
 
 public:
     AQSSensor(String name, sensor_e sensor, String unit,
@@ -58,14 +59,23 @@ public:
         sprintf(_topic, "Sensors/%s/%s", deviceID.c_str(), name.c_str());
         sprintf(_topic_1h, "Sensors/%s/%s/1h/", deviceID.c_str(), name.c_str());
         sprintf(_topic_24h, "Sensors/%s/%s/24h/", deviceID.c_str(), name.c_str());
+        _valid = false;
     }
 
     void publish(void)
     {
-        _publish = true;
+        if (_valid)
+        {
+            _publish = true;
+        }
+        else
+        {
+            Serial.printf("Sensor %s : Not published (invalid)\n", _name.c_str());
+        }
     }
 
-    String getName(void)
+    String
+    getName(void)
     {
         return _name;
     }
@@ -88,17 +98,18 @@ public:
 
     virtual void set(uint32_t value)
     {
-        if((value > _scaleMin) && (value < _scaleMax))
+        if ((value > _scaleMin) && (value < _scaleMax))
         {
             _value = value;
             _average1h.add(_value);
             _average24h.add(_value);
+            _valid = true;
         }
         else
         {
-            Serial.printf("Sensor %s: value out of bounds (%d)\n", _name.c_str(), value);
+            Serial.printf("Sensor %s set(%d): value out of bounds\n", _name.c_str(), _value);
+            _valid = false;
         }
-
     }
 
     uint32_t value() { return _value; }
@@ -113,7 +124,7 @@ public:
 
     sensor_e getSensor(void) { return _sensor; }
 
-    String getUnit(void) { return _unit;}
+    String getUnit(void) { return _unit; }
 
     uint32_t getMin(void) { return _scaleMin; }
     uint32_t getMax(void) { return _scaleMax; }